The effect of single large dose hydrocortisone treatment on IgM and IgG antibody production, morphological distribution of antibody producing cells and immunological memory.

The effect of a single subcutaneous dose of hydrocortisone (730 mg/kg ∼ 21-day LD) on the haemolysin response of mice to sheep erythrocyte antigen was examined. Hydrocortisone was administered once at times varying from 5 days before immunization with sheep erythrocytes to 9 days after antigen. Total suppression of the 7S haemolysin titre was brought about by treatment with single dose of 750 mg/kg in the period 5 days prior to antigen until 2 days after antigen; at the same time, the titre of 19S haemolysin exceeded the control 19S titre. Microplaque assay on the 5th day failed to confirm total suppression of 7S antibody synthesis, as 4 per cent of the splenic plaque-forming cells produced 7S. The same assay failed to verify the augmentation of 19S production on a cellular level, as the number of 19S plaque-forming was significantly decreased. Hydrocortisone could be shown to influence the morphology of the 19S antibody producing cells by increasing the percentage of mature cell types. A selective depressing activity by hydrocortisone on 7S memory was found. The theoretical implications of these findings are discussed.