DIFFERENTIAL INHIBITION OF T-CELL AND B-CELL RESPONSES TO INDIVIDUAL ANTIGENIC DETERMINANTS IN ORALLY TOLERIZED MICE

Immunological tolerance of systemic immunity can be induced by the ora l administration of an exogenous antigen, which is termed oral toleran ce. We examined whether there was a difference in the degree of tolera nce between individual antigenic determinants in oral tolerance. Feedi ng bovine alpha s1-casein, a major protein in cow's milk, as a constit uent of the diet induces oral tolerance in mice. However, a weak antib ody response can be elicited in the alpha s1-casein-fed animals by sub sequent immunization with the antigen. We examined the fine specificit y of such anti-alpha s1-casein antibodies produced in alpha s1-casein- fed mice. The results demonstrated that there was a difference in the inhibition of antibody response between different B cell determinants. Differential inhibition could also be observed for T cell responses. T cells specific for dominant determinants were preferentially toleriz ed, while those for cryptic determinants escaped oral tolerance. Our r esults imply the importance of antigen presentation for this different ial inhibition of antigenic determinants. We suggest that orally admin istered antigen does not induce tolerance to some of the B and T lymph ocyte repertoire which could potentially induce harmful food hypersens itivity.