The Journal of Allergy and Clinical Immunology
Volume 120, Issue 1 , Pages 207-208, July 2007

Clinical value of conjunctival allergen challenge in diagnosing allergic conjunctivitis related to latex

From the Department of Allergology, Medical University of Gdansk, Gdansk, Poland

published online 04 May 2007.

Article Outline

 

To the Editor:

An increasing incidence of latex allergy has been noted within the last decades. Health care workers, industry workers, and patients undergoing multiple medical interventions are at particular risk.1 Contact urticaria is the most common sign of latex allergy; however, other clinical manifestations, including localized or generalized urticaria, angioneurotic edema, rhinitis, conjunctivitis, and bronchial asthma, are not rare.1 The skin provocation test with latex gloves is a standardized diagnostic method used in patients with contact urticaria.2 In contrast, the final diagnosis of other latex allergies, particularly in patients with symptoms of conjunctivitis, is difficult, mainly because of the lack of a standardized allergen challenge.

Thus we studied the safety and sensitivity of conjunctival allergen challenge (CAC) with commercial latex extract in consecutive series of 37 patients (25 women and 12 men; mean age, 37.4 years; age range, 25-67 years) with a history of conjunctivitis caused by latex allergy. All patients had a diagnosed IgE-dependent latex allergy confirmed by means of either a positive skin prick test (SPT) response (Allergopharma, Reinbek, Germany) or a positive specific IgE result with k82 specific latex ImmunoCAP (Pharmacia, Uppsala, Sweden) but were in remission at the time of CAC.

The control group consisted of 30 subjects (19 women and 11 men; mean age, 23.8 years; age range, 22-25 years) with no conjunctivitis symptoms, negative SPT responses, and sIgE of less than 0.35 kU/L to latex.

CAC was performed according to a modification of the method of Abelson et al3 with the latex allergen extracts (100 PNU/mL, Allergopharma). None of the patients had taken any topical or antihistaminic oral drugs during the last month before the test. One drop (25 μL) of the latex extract with diluent (1:100) was applied in the conjunctival sac of one eye, and placebo (diluent: phosphate-buffered saline solution conserved with 0.4% phenol) was applied in the other, with the head leaned back. Overflow of the fluid was not observed. A conjunctival reaction was assessed after 30 minutes. If there was no response, the examined extract was applied with stronger diluents (1:10), and in the case of no reaction after the same time period, the last dose (1:1) was applied. The symptoms of conjunctivitis (itching, tearing, and redness) were scored as previously described3 for both eyes 5 and 30 minutes and 6 and 24 hours after the last allergen application. Clinical response was scored according to the scale proposed by Abelson et al.3 Each symptom (tearing, itching, and redness) was graded from 0 to 2 (0, no symptoms; 1, moderate symptoms; and 2, severe symptoms), and thus the total maximum possible score was 6. A challenge score of 3 or greater was considered positive.

CAC results with the use of latex allergen extract were positive in 35 (95%) patients in the study group and in none of the 30 control subjects. The 100-fold dilution of latex caused no response. Thirteen cases had positive results to 10-fold dilution and 22 to undiluted solution with a concentration of 100 PNU/mL.

For all methods used in the study, the sensitivity of the test was calculated according to the following formula: , where TP was the number of true-positive results and FN was the number of false-negative results. The sensitivities for diagnostic methods used in the study were as follows: CAC, 95%; SPT, 84%; and sIgE, 89%. No systemic or local severe adverse events related to CAC occurred during the study.

CAC has been previously used to detect allergy to aeroallergens because this method is considered easier and safer than nasal and bronchial challenge.4 The results of these studies suggested that the eye test was helpful both in causative diagnosis and in therapy monitoring.5 Some reports also showed that patients allergic to common aeroallergens with negative SPT responses and suspected ocular allergic symptoms had a positive reaction to specific eye challenge.4 However, these tests have been performed for a long time,6, 7 and CAC with latex was first described by Kurtz et al in 2001.8 Studied subjects were placed in the hooded exposure chamber with calibrated level of latex, and thus several organs, including the conjunctiva, respiratory tract, and skin, were provoked simultaneously.8

In the present study the commercial extract of latex was administered topically, and CAC turned out to be the most sensitive (95%) diagnostic procedure. The sensitivity of CAC was even stronger than that of SPT (84%), although the percentage of positive SPT responses with latex did not differ from those reported in other studies.2 The diagnostic efficacy of CAC in latex allergy was comparable with that of CAC with aeroallergens in atopic conjunctivitis.3, 4

Some authors reported adverse events during the challenge test.3 In our series no systemic or severe local adverse reactions were observed. Because specific immunotherapy for latex allergy is now available, CAC, with its sensitivity and safety, might facilitate the selection of patients for this treatment.

This study demonstrated that CAC with extract of latex allergens is a useful and safe method in the diagnosis of patients sensitive to latex. Because specific immunotherapy for latex allergy is now available, CAC might facilitate the selection of patients for this treatment.

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References 

  1. Slater JE. Latex allergy. J Allergy Clin Immunol. 1994;94:139–149
  2. Turjanmaa K. Allergy to natural rubber latex: a growing problem. Ann Med. 1994;26:297
  3. Abelson MB, Chambers WA, Smith LM. Conjunctival allergen challenge. A clinical approach to studying allergic conjunctivitis. Arch Ophthalmol. 1990;108:84–88
  4. Tuft L. The value of eye tests with inhalant allergens—a clinical study. Ann Allergy. 1967;25:183–191
  5. Abelson MB, Spitalny L. Combined analysis of two studies using the conjunctival allergen challenge model to evaluate olopatadine hydrochloride, a new ophthalmic antiallergic agent with dual activity. Am J Ophthalmol. 1998;125:797–804
  6. Peshkin MM. A dry pollen ophthalmic test in pollen asthma and hayfever patients negative to cutaneous tests. J Allergy. 1932;3:20–29
  7. Tuft L, Ettelson LN, Gupta K, Krueger C. Eye tests with inhalant allergens; their feasibility, indications and clinical value. J Allergy. 1959;30:492–505
  8. Kurtz KM, Hamilton RG, Schaefer JA, Adkinson NF. A hooded exposure chamber method for semiquantitative latex aeroallergen challenge. J Allergy Clin Immunol. 2001;107:178–184

 Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest.

PII: S0091-6749(07)00574-X

doi:10.1016/j.jaci.2007.03.012

The Journal of Allergy and Clinical Immunology
Volume 120, Issue 1 , Pages 207-208, July 2007

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