Specific immunotherapy with a standardized latex extract versus placebo in allergic healthcare workers

The prevalence of allergy to natural rubber latex proteins has increased over recent years among healthcare professionals but also in children undergoing multiple operations. Exposure to the antigen mainly occurs through the respiratory mucosa and the percutaneous route. Clinical manifestations range from urticaria to angioedema, rhinoconjunctivitis, bronchial asthma, or anaphylactic shock. Preventive measures have been proposed to reduce the risk of sensitization by using only powder-free or synthetic gloves and latex-free material in operating units, but this is not always possible.

The aim of this study was to investigate the efficacy and safety of specific immunotherapy in sensitized workers.

Seventeen patients with latex skin allergy and rhinitis (9 of whom also had asthma) were included in this randomized, double-blind, placebo-controlled trial (9 in the active group and 8 in the placebo group) for 1 year. Treatment started with a 2-day course of rush immunotherapy in hospital. Treatment efficacy was assessed after 6 and 12 months by means of symptom and medication scores recorded on diary cards. Conjunctival provocation tests were also performed.

Patients in the active treatment group had a significantly lower total rhinitis score after 6 (P <. 04) and 12 months (P <.05), conjunctivitis score after 6 months (P <. 02), and cutaneous score after 12 months (P <.03) than in the placebo group. Asthma symptoms after 6 or 12 months of treatment were not significantly different between the two groups after adjustment for baseline values. The global medication score was markedly decreased in the latex-treated group. A significant difference in conjunctival reactivity was observed in favor of the active group: the number of patients for whom the threshold dose was increased after 12 months of treatment was significantly greater in the active group than in the placebo group (P <.02). Most injections were well tolerated, but several adverse effects, including hypotension, urticaria, wheezing, and pharyngeal edema, were observed.

The clinical benefits observed during the present study included a significant improvement of rhinitis, conjunctivitis, and cutaneous symptoms. Immunotherapy also decreased allergen-specific conjunctival reactivity. Latex-specific immunotherapy may allow sensitized personnel to remain at work, but further trials need to be conducted in a larger number of patients.