Immunosuppressive effect of corticosteroids on rabbit's humoral and cellular response

The immunosuppressive effect of two of the most used steroids, 16-Methylen-prednisolone and betamethasone, was studied in rabbits sensitized to bovine serum albumin (BSA). In the steroid treated animals the hemagglutination and precipitation titres obtained in Boyden's test and gel-diffusion respectively, were strongly decreased as compared with the controls. The Arthus reaction was also inhibited. No response was detected in the lymphocyte transformation test (LTT) against the antigen (BSA) in the treated animals, and also the PHA induced transformation was suppressed but not completely abolished. A remarked decrease in the number of circulating mononuclear cells was observed in the treated animals. The number of T rosette-forming cells was also strongly decreased, but the percentage of B cells bearing IgG on their membrane detected by immunofluorescence offered only a slight decrease as compared with the controls. All these changes were observed earlier and more intensely in the Betamethasone treated rabbits.