The effect of alum-precipitated pyridine ragweed extract on guinea pigs: II. Comparison of passive cutaneous anaphylaxis with Arthus reactivity after single low dose

Abstract

To investigate further the enhanced antigenicity of alum-precipitated pyridine (APPR) as compared to aqueous ragweed extract (ARE), passive cutaneous anaphylaxis (PCA) experiments were performed using sera obtained from the guinea pigs prior to the studies for Arthus reactivity previously reported. 1 The APPR immunized animals produced a greater total number of Arthus reactions, whether moderate or maximum, and the sera from these same animals gave a larger total percentage of positive PCA tests, 39 of 120 (32.5) per cent, than did the ARE immunized animals, 5 of 36 (13.8 per cent). Chi square for this difference was 4.737 and is significant at the 5 per cent level. The APPR immunized animals appeared to develop two types of antibodies more consistently than the ARE immunized. Their sera gave positive PCA reactions earlier after immunization and with lower single doses of APPR than did ARE immunized animals. With immunizing doses of 10 μg of protein N or below, antibodies persisted longer in APPR immunized animals. On day 136, 10 of 10 animals immunized with this dose of APPR gave positive Arthus reactions and their sera produced 7 of 10 positive PCA tests. On the other hand, none of the ARE immunized animals developed Arthus reactions nor did their sera produce positive PCA tests.