Inhibition of Secondary Immune Responses in Vivoby Immunoregulatory Alpha Globulin (IRA)1

These studies demonstrate that IRA will suppress both primary and secondary immune responses as measured by a hemolytic plaque assay. Suppression of the secondary response occurs whether IRA is administered prior to the immunizing injection of antigen or prior to the challenge injection of antigen. The fact that IRA administered at the time of initial antigen exposure was able to inhibit the response to a second, or challenge, dose of that antigen; and that the secondary response was significantly less than a normal primary response suggests that IRA administered at the time of initial antigen exposure confers partial tolerance to that antigen.