Modulation of the immune system in the mouse. 1. Drug administration prior to antigen sensitization.

A model has been developed in the mouse in which methylated bovine serum albumin (MBSA) and sheep red blood cells have been used to produce delayed type hypersensitivity (DTH) and humoral immunity (HI), respectively. The time course between antigen sensitization and challenge was chosen such that cyclophosphamide (CY), administered prior to sensitization, produced DTH enhancement and also produced suppression of HI when administered at high doses. A number of other drugs have been examined in this model but only CY-like drugs, viz. alkylating agents, produced similar DTH enhancement. DTH was suppressed in a few cases. The HI response was enhanced or suppressed by a number of unrelated drugs. CY was the only alkylating agent to suppress the antibody titre. The mechanisms for these drug effects are uncertain. However, a number of drugs elicit effects on either DTH or HI which suggests there is selective removal of certain cell populations rather than non-specific cytotoxicity. Possible theories for the effects observed are discussed. These studies also suggest that CY possesses unique properties in this particular model.