Allergenic potential of gonadotrophic preparations in experimental animals: relevance of purity

Local reactions have been frequently reported following repeated injections of human menopausal gonadotrophins (HMG) for the treatment of infertility. Also immunoglobulin (Ig) E-mediated systemic reactions have sporadically been observed. Since most HMG preparations contain significant amounts of non-hormonal urine-derived proteins, it was suggested that these contaminating proteins are responsible for the various allergic reactions. In order to verify this hypothesis, different human follicle stimulating hormone (HFSH) and HMG preparations (Metrodin and Pergonal from Ares-Serono, and Humegon from Organon), were compared with a highly purified preparation (Metrodin HP from Ares-Serono) for the frequency and severity of allergic reactions induced in laboratory animals. The occurrence of anaphylactic shock or related symptoms was studied in sensitized guinea-pigs. The production of specific IgE was evaluated in serum from mice sensitized with the test drugs by the induction of passive cutaneous anaphylaxis in rats. In both models, two different schedules of sensitization were used. Severe allergic reactions were found in 20 of 7% of the guinea-pigs receiving highly purified FSH (Metrodin HP) in the two schedules, respectively, compared to 90 and 88% with the other preparations. Similarly significantly lower IgE titres were induced by highly purified FSH in respect to the other preparations. It can be concluded that the elimination of contaminating proteins significantly reduces the allergenicity of urine-derived HFSH preparations.