Lability of blocking antibody during ragweed immunotherapy

The long-term immunologic changes with allergy injection therapy have been widely studied. There are few data, however, on the immunologic response to a single injection during the course of this therapy. Ten patients who had attained maintenance (1:100 w/v) within six months and 13 patients who had been on maintenance longer than three years were compared. Following baseline studies patients received their standard ragweed injections and were followed without further injections for 30 days. Titrated prick tests to short ragweed, specific IgE to short ragweed and IgG antibody to ragweed AgE were determined at intervals during the 30 days. Baseline values of skin tests, specific IgE and specific IgG did not differ significantly for the two groups. Values for all three parameters did not fluctuate significantly during the study. This study suggests that blocking antibody levels are stable soon after reaching maintenance and that allergy injections can be safely administered at monthly intervals beginning at that time.