SAFETY AND EFFICACY OF ORAL IMMUNOTHERAPY WITH STANDARDIZED CAT EXTRACT

Fifty-three subjects with positive skin prick test results to cat extr act and rhinoconjunctival symptoms on exposure to cat dander were enro lled in a double-blind, placebo-controlled study of oral cat immunothe rapy. Responses were assessed by development of symptoms and nasal blo ckage on exposure to an apartment contaminated with cat dander, by tit rated skin prick tests, and by cat-specific IgG and IgE. A total cumul ative dose of 2.5 x 10(6) allergy units or 436 U Fel d I were administ ered over a period of 3 months. Both groups of subjects had significan tly fewer symtpoms on exposure to cat dander during the course of the study, but there was no significant difference between active and plac ebo groups. There were no significant changes in either group in nasal blockage, skin prick test results, or specific IgG levels. Both group s had significant increases in cat-specific IgE, but there were no dif ferences between groups. Subjects receiving active treatment had a sli ght excess of gastrointestinal complaints. Two subjects receiving acti ve treatment experienced systemic symptoms: one had pulmonary edema, a nd the other had persistent asthma and urticaria, which may have repre sented reactions to the treatment. We conclude that oral cat immunothe rapy with the preparation and doses used in this study is not effectiv e.