In 1997, the U.S. Food and Drug Administration granted an indication for the use of the Thin-Layer Rapid Use Epicutaneous (T.R.U.E.) test panels 1.1 and 2.1 as valuable, first-line screening tools in the diagnosis of delayed-type hypersensitivity reactions, allergic contact dermatitis (ACD). Many dermatologists utilize the T.R.U.E. test in their practices and refer to contact dermatitis referral centers when the T.R.U.E test fails to identify a relevant allergen. This being said, many relevant allergens are not detected by use of this screening tool alone1 and, for this reason, “Allergen Focus” has been expanded to cover the more highly relevant allergens encountered in clinical practice. This column attempts to answer some of the most frequent questions relating to the origin of and most common uses of these common allergens.
Contact Dermatides
The contact dermatides include, irritant contact dermatitis, allergic contact dermatitis and contact urticaria.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Allergic contact dermatitis (ACD) is a T-helper cell Type 1 (Th1)-dependent delayed-type (Type IV) hypersensitivity reaction, in which the instigating exogenous antigens are primarily small lipophilic chemicals (haptens) with a molecular weight less than 500 Daltons.
In certain instances chemicals can provoke both Type IV and Type I (immediate-type) hypersensitivity reactions. Type I reactions in the skin usually present as contact urticaria (the wheal and flare reaction). This is an IgE and mast cell-mediated immediate-type hypersensitivity reaction that can lead to anaphylaxis. The foremost example of this and the spotlight of this “Allergen Focus” is latex protein hypersensitivity.2,3
Clinical Illustration
A dental hygienist presented to the Occupational and Contact Dermatitis Clinic at the University of Minnesota for evaluation of a 2-year history of chronic hand dermatitis, primarily involving the dorsal surfaces of her hands. She had seen several physicians and tried multiple different hand soaps, moisturizers, and topical corticosteroids. She had a history of childhood eczema, was allergic to kiwi fruit, and reported the recent onset of hay fever symptoms during the work week, which improved on vacations and weekends.
From the West Indies to Love in the Operating Room — the Origin of the Natural Latex Rubber Glove
In the 15th century, European explorers documented the use of rubber shoes, balls and bottles by Central American people. Samples of rubber balls from the West Indies were brought to Europe on June 11, 1496, by Christopher Columbus. Previously, packed leather balls had been used in Europe, so the superior “bounce” of these novel rubber balls was quite sensational at the time.
The industrialization of natural rubber latex became possible after Charles Macintosh, an industrial chemist in Glasgow, Scotland, and his medical student, James Syme, discovered that a naphtha-based rubber solution could “waterproof” fabric in 1818 (the “macintosh”).
While the rubber industry thrived in the cool climate of Great Britain, wider climate variations in the United States resulted in sticky (if too hot) or brittle (if too cold) commercial products.
In 1841, an American working on this problem, Charles Goodyear, accidentally discovered vulcanization, a process that utilizes sulfur to stabilize the elastic properties of rubber. From that time on, the natural rubber industry rapidly expanded.4,5
Permeable gloves, such as those made from sheep cecum, were initially used in obstetrics in the 1700s. In the 1800s, heavy rubber gloves were primarily used in postmortem examinations. In 1893, J.C. Bloodgood provided gloves to all members of his surgical team.
Despite these early developments, William Stewart Halstead is widely considered to be the “Father of the Surgical Glove.” He hired the Goodyear Rubber company to manufacture thin gloves for his head operating room nurse and wife-to-be, Caroline Hampton, who had developed dermatitis from harsh disinfectant chemicals.6
Later, the value of gloves for prevention of infection transmission became evident. In 1928, a “dipping” manufacturing process for gloves was developed that resulted in a thinner, more elastic, stronger glove. The enhanced tactile ability with thinner gloves was critical for intricate procedures.
Surgical gloves originally were intended to be reused multiple times after they were cleaned and sterilized. Disposable gloves only became widely used in industrialized countries in the late 1960s.
On Aug. 21, 1987, the Centers for Disease Control and Prevention published a document which became known as “universal precautions.”7 These recommendations called for routine use of barriers, such as gloves, when contact with body fluids was possible.
The demand for disposable gloves subsequently skyrocketed; glove imports rose eleven-fold in the next 4 years. Many of these gloves were rapidly produced and were poorly compounded with very high levels of latex proteins, resulting in the sensitization of thousands of people. Although many of those inexperienced manufacturers later went out of business and the quality of disposable latex gloves dramatically improved, those who were sensitized continued to have problems with latex.3
Allergy to Natural Rubber Latex
Natural latex refers to the mlky sap of the Hevea brasiliensis tree. This is compounded with rubber accelerators (such as thiurams, carbamates, and mercaptobenzothiazoles) and other compounds to form a commercial product. Two types of allergic reactions to natural rubber latex products are well recognized:
1. Type I, immediate-type, IgE-mediated hypersensitivity
2. Type IV, delayed-type, cell-mediated hypersensitivity. (See Table 1.)
While there are rare reports of Type IV reactions to natural latex itself,8,9,10 Type IV reactions to rubber are typically due to allergens in the accelerators and other additives used in the manufacturing process.11
Hundreds of proteins in natural latex have been shown to bind IgE antibodies, and although several major antigens have been identified, patterns by individual and by risk group vary. Major antigens are listed in Table 2.12 Unfortunately, many of the major antigens have vital functions for biosynthesis of natural latex. Products that are thin and stretchable (e.g., gloves, condoms, balloons) are more likely to cause problems for individuals allergic to latex than those made of dried sheets of rubber (e.g., tires, erasers, rubber pads).
Several risk factors have been identified for Type I allergy to latex. (See Table 3.) Sensitivity to latex in the general population is likely less than 1%.3 Most studies indicate that occupational exposure to natural rubber latex increases the risk of sensitivity up to 20%.13 Individuals who have a history of multiple surgical procedures14 or frequent mucosal exposure to natural rubber latex products are also at increased risk (up to 60% in some studies), as are females and those who are atopic. Several food allergies (especially to tropical fruits) have been associated with latex sensitivity.15 (See Table 4.) It is thought that the structural similarities of natural rubber latex and plant proteins produce cross-reactivity.
Testing for Latex Allergy
Importantly, both Type I allergy to natural rubber latex and Type IV allergy to rubber accelerators can co-exist. Many non-latex synthetic rubber gloves also utilize the same accelerators that are in natural rubber latex products. Therefore, it is worthwhile to evaluate patients for both types of allergy by patch-testing to accelerators as well as testing for Type I allergy to latex.
The most commonly used tests for latex allergy include in vitro antibody blood tests, skin prick test, and use test.3
A radioallergosorbent test (RAST) is a blood test in which a solid-phase allergen is incubated with serum; the amount of bound circulating antibody is measured and reported. These tests are relatively inexpensive, but they measure only circulating antibodies (which may diminish with latex avoidance) and have low sensitivity (50% to 90%).
A skin prick test involves placing a drop of diluted latex allergen solution (usually a mix of several latex allergens or solution from several types of gloves) on the forearm and pricking through this with a lancet. The area is observed for 15 minutes. An urticarial wheal that measures at least half the diameter of the histamine control is considered positive. If no reaction is observed, then sequential higher concentrations may be tested.
A use test involves applying a known highly allergenic glove to the patient’s wet hand. This is typically done in
15-minute periods of increasing exposure, starting with the fingertip, then the finger, followed by the whole hand. Urticarial wheals in the area of exposure indicate a positive test. Several variations of these tests and more specialized tests can be performed by an allergist.
In most dermatological practices, it is practical to order a latex RAST. If this is negative, then consider referring to an allergist. Unfortunately, no FDA-approved, latex prick test solutions are available in the United States. Some allergists make their own solutions from glove pieces or utilize commercial solutions from Canada or Europe.
Because of the risk of anaphylaxis with prick and use testing, these tests should only be performed in settings with resuscitation equipment and trained personnel available.
The Value of This Patient Case
This patient was found to have high amounts of circulating antibodies to latex (positive RAST test) and was also patch-test positive to mercaptobenzothiazole. While the patient had switched to nitrile gloves, thus avoiding direct contact to latex, she continued to have dermatitis because of the presence of mercaptobenzothiazole in her nitrile gloves. She continued to have respiratory symptoms due to the use of powdered latex gloves by her co-workers. This presumably occurred when the latex proteins in their gloves were absorbed into starch particles (in the powder), which became airborne, thus causing her respiratory symptoms.
Information was provided on latex avoidance for both home and work products. (See Tables 5 and 6.) More detailed tables of gloves and other products can also be found on the American Contact Dermatitis Society Web site (contactderm.org). Importantly, the patient was counseled on the importance of notifying family and personal healthcare providers of her allergy to latex. Fortunately, now most hospitals and physician’s offices have removed many latex products. At work, she and her co-workers switched to vinyl exam gloves, and she was able to remain symptom-free.
In 1997, the U.S. Food and Drug Administration granted an indication for the use of the Thin-Layer Rapid Use Epicutaneous (T.R.U.E.) test panels 1.1 and 2.1 as valuable, first-line screening tools in the diagnosis of delayed-type hypersensitivity reactions, allergic contact dermatitis (ACD). Many dermatologists utilize the T.R.U.E. test in their practices and refer to contact dermatitis referral centers when the T.R.U.E test fails to identify a relevant allergen. This being said, many relevant allergens are not detected by use of this screening tool alone1 and, for this reason, “Allergen Focus” has been expanded to cover the more highly relevant allergens encountered in clinical practice. This column attempts to answer some of the most frequent questions relating to the origin of and most common uses of these common allergens.
Contact Dermatides
The contact dermatides include, irritant contact dermatitis, allergic contact dermatitis and contact urticaria.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Allergic contact dermatitis (ACD) is a T-helper cell Type 1 (Th1)-dependent delayed-type (Type IV) hypersensitivity reaction, in which the instigating exogenous antigens are primarily small lipophilic chemicals (haptens) with a molecular weight less than 500 Daltons.
In certain instances chemicals can provoke both Type IV and Type I (immediate-type) hypersensitivity reactions. Type I reactions in the skin usually present as contact urticaria (the wheal and flare reaction). This is an IgE and mast cell-mediated immediate-type hypersensitivity reaction that can lead to anaphylaxis. The foremost example of this and the spotlight of this “Allergen Focus” is latex protein hypersensitivity.2,3
Clinical Illustration
A dental hygienist presented to the Occupational and Contact Dermatitis Clinic at the University of Minnesota for evaluation of a 2-year history of chronic hand dermatitis, primarily involving the dorsal surfaces of her hands. She had seen several physicians and tried multiple different hand soaps, moisturizers, and topical corticosteroids. She had a history of childhood eczema, was allergic to kiwi fruit, and reported the recent onset of hay fever symptoms during the work week, which improved on vacations and weekends.
From the West Indies to Love in the Operating Room — the Origin of the Natural Latex Rubber Glove
In the 15th century, European explorers documented the use of rubber shoes, balls and bottles by Central American people. Samples of rubber balls from the West Indies were brought to Europe on June 11, 1496, by Christopher Columbus. Previously, packed leather balls had been used in Europe, so the superior “bounce” of these novel rubber balls was quite sensational at the time.
The industrialization of natural rubber latex became possible after Charles Macintosh, an industrial chemist in Glasgow, Scotland, and his medical student, James Syme, discovered that a naphtha-based rubber solution could “waterproof” fabric in 1818 (the “macintosh”).
While the rubber industry thrived in the cool climate of Great Britain, wider climate variations in the United States resulted in sticky (if too hot) or brittle (if too cold) commercial products.
In 1841, an American working on this problem, Charles Goodyear, accidentally discovered vulcanization, a process that utilizes sulfur to stabilize the elastic properties of rubber. From that time on, the natural rubber industry rapidly expanded.4,5
Permeable gloves, such as those made from sheep cecum, were initially used in obstetrics in the 1700s. In the 1800s, heavy rubber gloves were primarily used in postmortem examinations. In 1893, J.C. Bloodgood provided gloves to all members of his surgical team.
Despite these early developments, William Stewart Halstead is widely considered to be the “Father of the Surgical Glove.” He hired the Goodyear Rubber company to manufacture thin gloves for his head operating room nurse and wife-to-be, Caroline Hampton, who had developed dermatitis from harsh disinfectant chemicals.6
Later, the value of gloves for prevention of infection transmission became evident. In 1928, a “dipping” manufacturing process for gloves was developed that resulted in a thinner, more elastic, stronger glove. The enhanced tactile ability with thinner gloves was critical for intricate procedures.
Surgical gloves originally were intended to be reused multiple times after they were cleaned and sterilized. Disposable gloves only became widely used in industrialized countries in the late 1960s.
On Aug. 21, 1987, the Centers for Disease Control and Prevention published a document which became known as “universal precautions.”7 These recommendations called for routine use of barriers, such as gloves, when contact with body fluids was possible.
The demand for disposable gloves subsequently skyrocketed; glove imports rose eleven-fold in the next 4 years. Many of these gloves were rapidly produced and were poorly compounded with very high levels of latex proteins, resulting in the sensitization of thousands of people. Although many of those inexperienced manufacturers later went out of business and the quality of disposable latex gloves dramatically improved, those who were sensitized continued to have problems with latex.3
Allergy to Natural Rubber Latex
Natural latex refers to the mlky sap of the Hevea brasiliensis tree. This is compounded with rubber accelerators (such as thiurams, carbamates, and mercaptobenzothiazoles) and other compounds to form a commercial product. Two types of allergic reactions to natural rubber latex products are well recognized:
1. Type I, immediate-type, IgE-mediated hypersensitivity
2. Type IV, delayed-type, cell-mediated hypersensitivity. (See Table 1.)
While there are rare reports of Type IV reactions to natural latex itself,8,9,10 Type IV reactions to rubber are typically due to allergens in the accelerators and other additives used in the manufacturing process.11
Hundreds of proteins in natural latex have been shown to bind IgE antibodies, and although several major antigens have been identified, patterns by individual and by risk group vary. Major antigens are listed in Table 2.12 Unfortunately, many of the major antigens have vital functions for biosynthesis of natural latex. Products that are thin and stretchable (e.g., gloves, condoms, balloons) are more likely to cause problems for individuals allergic to latex than those made of dried sheets of rubber (e.g., tires, erasers, rubber pads).
Several risk factors have been identified for Type I allergy to latex. (See Table 3.) Sensitivity to latex in the general population is likely less than 1%.3 Most studies indicate that occupational exposure to natural rubber latex increases the risk of sensitivity up to 20%.13 Individuals who have a history of multiple surgical procedures14 or frequent mucosal exposure to natural rubber latex products are also at increased risk (up to 60% in some studies), as are females and those who are atopic. Several food allergies (especially to tropical fruits) have been associated with latex sensitivity.15 (See Table 4.) It is thought that the structural similarities of natural rubber latex and plant proteins produce cross-reactivity.
Testing for Latex Allergy
Importantly, both Type I allergy to natural rubber latex and Type IV allergy to rubber accelerators can co-exist. Many non-latex synthetic rubber gloves also utilize the same accelerators that are in natural rubber latex products. Therefore, it is worthwhile to evaluate patients for both types of allergy by patch-testing to accelerators as well as testing for Type I allergy to latex.
The most commonly used tests for latex allergy include in vitro antibody blood tests, skin prick test, and use test.3
A radioallergosorbent test (RAST) is a blood test in which a solid-phase allergen is incubated with serum; the amount of bound circulating antibody is measured and reported. These tests are relatively inexpensive, but they measure only circulating antibodies (which may diminish with latex avoidance) and have low sensitivity (50% to 90%).
A skin prick test involves placing a drop of diluted latex allergen solution (usually a mix of several latex allergens or solution from several types of gloves) on the forearm and pricking through this with a lancet. The area is observed for 15 minutes. An urticarial wheal that measures at least half the diameter of the histamine control is considered positive. If no reaction is observed, then sequential higher concentrations may be tested.
A use test involves applying a known highly allergenic glove to the patient’s wet hand. This is typically done in
15-minute periods of increasing exposure, starting with the fingertip, then the finger, followed by the whole hand. Urticarial wheals in the area of exposure indicate a positive test. Several variations of these tests and more specialized tests can be performed by an allergist.
In most dermatological practices, it is practical to order a latex RAST. If this is negative, then consider referring to an allergist. Unfortunately, no FDA-approved, latex prick test solutions are available in the United States. Some allergists make their own solutions from glove pieces or utilize commercial solutions from Canada or Europe.
Because of the risk of anaphylaxis with prick and use testing, these tests should only be performed in settings with resuscitation equipment and trained personnel available.
The Value of This Patient Case
This patient was found to have high amounts of circulating antibodies to latex (positive RAST test) and was also patch-test positive to mercaptobenzothiazole. While the patient had switched to nitrile gloves, thus avoiding direct contact to latex, she continued to have dermatitis because of the presence of mercaptobenzothiazole in her nitrile gloves. She continued to have respiratory symptoms due to the use of powdered latex gloves by her co-workers. This presumably occurred when the latex proteins in their gloves were absorbed into starch particles (in the powder), which became airborne, thus causing her respiratory symptoms.
Information was provided on latex avoidance for both home and work products. (See Tables 5 and 6.) More detailed tables of gloves and other products can also be found on the American Contact Dermatitis Society Web site (contactderm.org). Importantly, the patient was counseled on the importance of notifying family and personal healthcare providers of her allergy to latex. Fortunately, now most hospitals and physician’s offices have removed many latex products. At work, she and her co-workers switched to vinyl exam gloves, and she was able to remain symptom-free.
In 1997, the U.S. Food and Drug Administration granted an indication for the use of the Thin-Layer Rapid Use Epicutaneous (T.R.U.E.) test panels 1.1 and 2.1 as valuable, first-line screening tools in the diagnosis of delayed-type hypersensitivity reactions, allergic contact dermatitis (ACD). Many dermatologists utilize the T.R.U.E. test in their practices and refer to contact dermatitis referral centers when the T.R.U.E test fails to identify a relevant allergen. This being said, many relevant allergens are not detected by use of this screening tool alone1 and, for this reason, “Allergen Focus” has been expanded to cover the more highly relevant allergens encountered in clinical practice. This column attempts to answer some of the most frequent questions relating to the origin of and most common uses of these common allergens.
Contact Dermatides
The contact dermatides include, irritant contact dermatitis, allergic contact dermatitis and contact urticaria.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Irritant contact dermatitis, the most common form, accounts for approximately 80% of environmental/occupational-based dermatoses, and occurs when the skin comes in contact with a caustic chemical; no prior sensitization is required.
Allergic contact dermatitis (ACD) is a T-helper cell Type 1 (Th1)-dependent delayed-type (Type IV) hypersensitivity reaction, in which the instigating exogenous antigens are primarily small lipophilic chemicals (haptens) with a molecular weight less than 500 Daltons.
In certain instances chemicals can provoke both Type IV and Type I (immediate-type) hypersensitivity reactions. Type I reactions in the skin usually present as contact urticaria (the wheal and flare reaction). This is an IgE and mast cell-mediated immediate-type hypersensitivity reaction that can lead to anaphylaxis. The foremost example of this and the spotlight of this “Allergen Focus” is latex protein hypersensitivity.2,3
Clinical Illustration
A dental hygienist presented to the Occupational and Contact Dermatitis Clinic at the University of Minnesota for evaluation of a 2-year history of chronic hand dermatitis, primarily involving the dorsal surfaces of her hands. She had seen several physicians and tried multiple different hand soaps, moisturizers, and topical corticosteroids. She had a history of childhood eczema, was allergic to kiwi fruit, and reported the recent onset of hay fever symptoms during the work week, which improved on vacations and weekends.
From the West Indies to Love in the Operating Room — the Origin of the Natural Latex Rubber Glove
In the 15th century, European explorers documented the use of rubber shoes, balls and bottles by Central American people. Samples of rubber balls from the West Indies were brought to Europe on June 11, 1496, by Christopher Columbus. Previously, packed leather balls had been used in Europe, so the superior “bounce” of these novel rubber balls was quite sensational at the time.
The industrialization of natural rubber latex became possible after Charles Macintosh, an industrial chemist in Glasgow, Scotland, and his medical student, James Syme, discovered that a naphtha-based rubber solution could “waterproof” fabric in 1818 (the “macintosh”).
While the rubber industry thrived in the cool climate of Great Britain, wider climate variations in the United States resulted in sticky (if too hot) or brittle (if too cold) commercial products.
In 1841, an American working on this problem, Charles Goodyear, accidentally discovered vulcanization, a process that utilizes sulfur to stabilize the elastic properties of rubber. From that time on, the natural rubber industry rapidly expanded.4,5
Permeable gloves, such as those made from sheep cecum, were initially used in obstetrics in the 1700s. In the 1800s, heavy rubber gloves were primarily used in postmortem examinations. In 1893, J.C. Bloodgood provided gloves to all members of his surgical team.
Despite these early developments, William Stewart Halstead is widely considered to be the “Father of the Surgical Glove.” He hired the Goodyear Rubber company to manufacture thin gloves for his head operating room nurse and wife-to-be, Caroline Hampton, who had developed dermatitis from harsh disinfectant chemicals.6
Later, the value of gloves for prevention of infection transmission became evident. In 1928, a “dipping” manufacturing process for gloves was developed that resulted in a thinner, more elastic, stronger glove. The enhanced tactile ability with thinner gloves was critical for intricate procedures.
Surgical gloves originally were intended to be reused multiple times after they were cleaned and sterilized. Disposable gloves only became widely used in industrialized countries in the late 1960s.
On Aug. 21, 1987, the Centers for Disease Control and Prevention published a document which became known as “universal precautions.”7 These recommendations called for routine use of barriers, such as gloves, when contact with body fluids was possible.
The demand for disposable gloves subsequently skyrocketed; glove imports rose eleven-fold in the next 4 years. Many of these gloves were rapidly produced and were poorly compounded with very high levels of latex proteins, resulting in the sensitization of thousands of people. Although many of those inexperienced manufacturers later went out of business and the quality of disposable latex gloves dramatically improved, those who were sensitized continued to have problems with latex.3
Allergy to Natural Rubber Latex
Natural latex refers to the mlky sap of the Hevea brasiliensis tree. This is compounded with rubber accelerators (such as thiurams, carbamates, and mercaptobenzothiazoles) and other compounds to form a commercial product. Two types of allergic reactions to natural rubber latex products are well recognized:
1. Type I, immediate-type, IgE-mediated hypersensitivity
2. Type IV, delayed-type, cell-mediated hypersensitivity. (See Table 1.)
While there are rare reports of Type IV reactions to natural latex itself,8,9,10 Type IV reactions to rubber are typically due to allergens in the accelerators and other additives used in the manufacturing process.11
Hundreds of proteins in natural latex have been shown to bind IgE antibodies, and although several major antigens have been identified, patterns by individual and by risk group vary. Major antigens are listed in Table 2.12 Unfortunately, many of the major antigens have vital functions for biosynthesis of natural latex. Products that are thin and stretchable (e.g., gloves, condoms, balloons) are more likely to cause problems for individuals allergic to latex than those made of dried sheets of rubber (e.g., tires, erasers, rubber pads).
Several risk factors have been identified for Type I allergy to latex. (See Table 3.) Sensitivity to latex in the general population is likely less than 1%.3 Most studies indicate that occupational exposure to natural rubber latex increases the risk of sensitivity up to 20%.13 Individuals who have a history of multiple surgical procedures14 or frequent mucosal exposure to natural rubber latex products are also at increased risk (up to 60% in some studies), as are females and those who are atopic. Several food allergies (especially to tropical fruits) have been associated with latex sensitivity.15 (See Table 4.) It is thought that the structural similarities of natural rubber latex and plant proteins produce cross-reactivity.
Testing for Latex Allergy
Importantly, both Type I allergy to natural rubber latex and Type IV allergy to rubber accelerators can co-exist. Many non-latex synthetic rubber gloves also utilize the same accelerators that are in natural rubber latex products. Therefore, it is worthwhile to evaluate patients for both types of allergy by patch-testing to accelerators as well as testing for Type I allergy to latex.
The most commonly used tests for latex allergy include in vitro antibody blood tests, skin prick test, and use test.3
A radioallergosorbent test (RAST) is a blood test in which a solid-phase allergen is incubated with serum; the amount of bound circulating antibody is measured and reported. These tests are relatively inexpensive, but they measure only circulating antibodies (which may diminish with latex avoidance) and have low sensitivity (50% to 90%).
A skin prick test involves placing a drop of diluted latex allergen solution (usually a mix of several latex allergens or solution from several types of gloves) on the forearm and pricking through this with a lancet. The area is observed for 15 minutes. An urticarial wheal that measures at least half the diameter of the histamine control is considered positive. If no reaction is observed, then sequential higher concentrations may be tested.
A use test involves applying a known highly allergenic glove to the patient’s wet hand. This is typically done in
15-minute periods of increasing exposure, starting with the fingertip, then the finger, followed by the whole hand. Urticarial wheals in the area of exposure indicate a positive test. Several variations of these tests and more specialized tests can be performed by an allergist.
In most dermatological practices, it is practical to order a latex RAST. If this is negative, then consider referring to an allergist. Unfortunately, no FDA-approved, latex prick test solutions are available in the United States. Some allergists make their own solutions from glove pieces or utilize commercial solutions from Canada or Europe.
Because of the risk of anaphylaxis with prick and use testing, these tests should only be performed in settings with resuscitation equipment and trained personnel available.
The Value of This Patient Case
This patient was found to have high amounts of circulating antibodies to latex (positive RAST test) and was also patch-test positive to mercaptobenzothiazole. While the patient had switched to nitrile gloves, thus avoiding direct contact to latex, she continued to have dermatitis because of the presence of mercaptobenzothiazole in her nitrile gloves. She continued to have respiratory symptoms due to the use of powdered latex gloves by her co-workers. This presumably occurred when the latex proteins in their gloves were absorbed into starch particles (in the powder), which became airborne, thus causing her respiratory symptoms.
Information was provided on latex avoidance for both home and work products. (See Tables 5 and 6.) More detailed tables of gloves and other products can also be found on the American Contact Dermatitis Society Web site (contactderm.org). Importantly, the patient was counseled on the importance of notifying family and personal healthcare providers of her allergy to latex. Fortunately, now most hospitals and physician’s offices have removed many latex products. At work, she and her co-workers switched to vinyl exam gloves, and she was able to remain symptom-free.
