The suppressive effect of circulating specific antibody on the response to oral immunisation with Vibrio cholerae.

Species IgG antibody given intravenously 3-4 hours prior to oral immunisation with Vibrio cholerae led to a specific depression of both the systemic and loca limmune response. One vibriocidal unit of IgG antibody, which itself would given undetectable levels of circulating specific antibody, was significantly immunosuppressive. The suppression is considered to be due to central repression of the antigen-reactive lymphocyte, rather than to antigen exclusion at the gut mucosal surface. The repression appeared less pronounced in some immunoglobulin classes than in others.