Comparative evaluation of Type 1 latex hypersensitivity in patients with chronic urticaria, rubber factory workers and healthy control subjects

Impact of contact sensitization in chronic spontaneous urticaria

INTRODUCTION

Patch testing is performed to diagnose allergic contact dermatitis to avoid exposure to the revealed contact allergens. Nevertheless, patch testing is not routinely performed in the evaluation of patients with chronic idiopathic (spontaneous) urticaria (CIU). The objective of this study was to determine the frequency of sensitization to patch test allergens in severe CIU and assess a role of the allergen avoidance in CIU remission.

METHODS

The cases of patients with severe CIU were retrospectively studied. The patients were patch tested using T.R.U.E. TEST. Three groups were studied: CIU with positive patch test group; CIU with negative patch test group and control group, which included the cases of not patch-tested patients with CIU. The groups were followed up monthly to assess changes in Chronic Urticaria Severity Score (CUSS) after allergen avoidance.

RESULTS

Forty-three subjects with severe CIU were patch tested. Nickel sulphate was positive in 4 (9.3%) cases, potassium dichromate in 2 (4.7%) cases, cobalt, balsam of Peru, paraphenylene diamine, fragrance mix and epoxy resin were positive in 1 (2.3%) case. Their baseline CUSS (5.4 ± 0.5) improved significantly after 1 month of allergen avoidance (3.2 ± 1.1; P < 0.001); but similar improvement of CUSS (5.3 ± 0.5) was seen in 34 patients with CIU with negative patch test (3.2 ± 1.3; P < 0.001) and in 49 patients with CIU of control group (5.2 ± 0.4 to 3.4 ± 1.3; P < 0 < 0.001) after 1 month.

CONCLUSIONS

There is no relationship between avoidance of contact allergens and the course of CIU.

Erythema multiforme-like eruption due to carbamates and thiuram

Report of a case of erythema multiforme-like eruption due to the use of rubber gloves. After several complementary studies, including epicutaneous and skin prick tests, we concluded that the eruption was secondary to sensitization to carbamates and thiuram. The main differential diagnosis in this case was allergic contact dermatitis to latex in natural rubber gloves. This entity is less frequent than might be expected, because it is usually due to intermediate chemical compounds used in rubber manufacturing, such as vulcanization accelerators; among of these latter compounds are thiurams and carbamates. Erythema multiforme-like eruption is a rare manifestation of contact dermatitis. Several cases have been reported, most of which have been due to contact with plants, metals or topical non-steroidal anti-inflammatory drugs. Its mechanism is still unclear, but it seems to be a type IV hypersensitivity reaction.

Toxicological and immunological aspects of occupational latex allergy

Latex allergy continues to be an important occupational health problem as latex products are used increasingly worldwide, particularly in healthcare. Although there are few epidemiological studies on the incidence of latex allergy, there has been an increase in the number of case reports over the last 10 years and, based on skin-prick tests, estimates of prevalence of latex allergy in healthcare workers range from 2% to 17%. The allergic health effects arise either from the latex proteins, generally causing a type I immediate hypersensitivity reaction, or from the chemicals added to latex during processing, causing a type IV delayed hypersensitivity reaction. Clinical manifestations of latex allergy depend on the route of exposure and occur by direct contact either with skin or mucosa, or by inhalation. The diagnosis of latex allergy is based on the history, skin tests, serological tests and challenge tests. Thirteen latex allergens have been identified and isolated so far from natural rubber latex. They differ in their potential to elicit immunological responses in individuals allergic to latex and thus have been designated as major or minor allergens. In latex gloves, cornstarch powder used as a donning agent carries latex proteins, thereby increasing inhalational and mucosal exposure to latex proteins. There also appears to be a positive correlation between protein content and allergenicity of gloves. The use of powder-free, low-protein gloves is effective in reducing symptoms and markers of sensitisation. Alternatives to latex gloves, such as nitrile or vinyl gloves are available but may be inferior in respect to manual dexterity and biological impermeability.

Latex allergy and skin

PURPOSE OF REVIEW

In this review we address the prevalence and outcome of latex allergy in health care workers (HCWs). Recent findings in natural rubber latex (NRL) allergens and trials of specific immunotherapy (SIT) are also of interest.

RECENT FINDINGS

A study involving skin prick test (SPT) screening in HCWs in Russia and adjacent countries found a prevalence of latex allergy of 1.9%. Questionnaire studies performed in Wales and in the USA identified prevalence rates of about 0.6%. An intervention undertaken at the Mayo Clinic, in which only gloves with low or undetectable allergen levels were allowed, reduced markedly the incidence of NRL allergy. Two studies, one from Finland and another from Ohio, showed that outcomes in latex-allergic HCWs are generally good. A study involving SPT screening showed that 6% of construction workers had latex allergy. A questionnaire study among allergists practicing in the USA showed that 62% performed latex SPT and 6% reported anaphylaxis, which mostly occurred while using a homemade SPT solution. Hev b 2, Hev b 5, Hev b 6.01 and Hev b 13 produced positive SPT reactions in over 60% of latex-allergic individuals. Topical application of NRL in a murine model of protein contact dermatitis caused a striking increase in prohevein-specific (Hev b 6.01) immunoglobulin E levels, together with a T-helper-2 type dermatitis. A placebo-controlled SIT trial with NRL extract alleviated cutaneous symptoms but caused some systemic reactions in latex-allergic patients.

SUMMARY

Low prevalence rates suggest that the peak of the latex allergy epidemic has already passed in HCWs. Hospital-wide interventions requiring use of low-allergen gloves reduce sensitization and changing gloves to nonlatex ones, or even using low-allergen latex gloves, in the affected individuals appears to confer adequate secondary prevention. In the USA there is an urgent need for standardized latex SPT reagent. Hev b 5 and Hev b 6.01 are major in vivo NRL allergens. Findings in mice suggest that NRL proteins eluting from latex gloves may also cause hand eczema in humans. SIT with NRL extract must still be considered an experimental treatment.