[Treatment perspectives: immunotherapy with latex].

Latex allergy currently constitutes a serious problem because of the severity of its symptoms and the at-risk groups it affects. Since complete avoidance of this substance is practically impossible, in the last few years intense efforts have been made to standardize a latex extract with the aim not only of improving clinical diagnosis but also of being able to offer other therapeutic alternatives, such as specific immunotherapy.Since 1998, reports of immunotherapy with oral (three patients) subcutaneous (one patient) and sublingual latex desensitization (one patient) have been published. In all cases, clinical improvement was evident. In 2000, Laynadier published the first pilot study, a phase IIB multicenter, randomized, double-blind, placebo-controlled trial that evaluated the efficacy and safety of specific immunotherapy with latex in patients with occupational allergy. Twenty health care workers without obvious latex exposure and with latex allergy-induced symptoms of rhinitis and/or asthma were included. Treatment started with a 2-day course of rush immunotherapy in hospital and maintenance therapy was continued for 1 year. Efficacy was assessed by symptom and medication scores and by variation in the conjunctival reactivity threshold. The safety of the extract was also evaluated. In the overall analysis of symptom score, the treated group showed a marked improvement and the medication score was significantly lower in patients in the active treatment group than in the placebo group. Concerning safety, almost half the patients receiving active treatment showed local reactions starting with the first injection and four of the nine patients in this group suffered moderate-to-severe systemic reactions. In view of this first clinical trial, it can be concluded that this treatment is effective but that its tolerance is low.A second clinical trial with the same characteristics and extract is currently underway. Its aim is to validate the previous protocol, confirm the efficacy of specific immunotherapy with latex, improve its safety and, if possible, determine the optimal dose.J. Sastre et al. have recently (Formigal 2002) presented the results of the first double-blind study with latex immunotherapy using an extract standardized by the ALK-Abelló-España group. The authors included 24 patients with latex sensitization and symptoms of occupational allergy. To diagnose respiratory allergy, an inhalation challenge was performed in a closed 7-m2 chamber and, in case of contact urticaria, glove-wearing and rubbing tests were performed, using a vinyl glove as negative control. Treatment consisted of a first phase of incremental doses for 14 weeks, with 18 injections, followed by maintenance doses for 6 months. Sixteen patients received active treatment and 8 received placebo. Of the 578 doses administered, adverse effects were observed in 41 (7.1 %). There were 21 immediate systemic reactions (5.7 % of the doses) and 10 delayed systemic reactions (2.6 % of the doses). Adverse effects were more frequent in patients with underlying respiratory disease (p < 0.05). After 6 months' treatment, a clear improvement in the cutaneous response index was found in the active treatment group and in the rubbing and glove-wearing tests. The authors conclude that the immunotherapy tested was a high-risk treatment and that the greatest clinical improvement was found in cutaneous symptoms.In conclusion, although effective, latex immunotherapy is currently a high-risk treatment.