[The pathogenesis of postvaccinal complications]

Paraspecific reactions to vaccines are -- induction of autoimmune mechanisms, -- immunosuppression, -- induction of inflammation (i.e. "reactogenicity"). These undesirable side effects of vaccination are important factors in pathogenesis of postvaccinal complications. Using the model of experimental vaccinia virus infection the paraspecific reactions could be demonstrated in several animal species. Cell mediated hypersensitivity to brain tissue antigen and basic encephalitogenic protein occurred following vaccinia infection in guinea pigs. In infected rabbits humoral anti-brain antibodies could be detected. The immune response to sheep erythrocytes in mice was tested by determining the number of plaque forming cells in the spleen after specific immunization. Vaccinia virus injected prior to or simultaneously with immunization strongly reduced the number of plaque forming cells in the spleen. The reactogenicity of bacterial and viral vaccines could be determined by means of a simple hemolytic plaque assay in mice. This assay represents the degree of enzymatic lysosomal activity of macrophages. The methods described might be useful to test the innocuity and tolerance of new vaccines.