Affinity of T and B lymphocyte receptors for hapten determinants

Abstract

AbstractThe affinity of anti‐hapten antibodies, produced by single cells, was studied by hapten inhibition of plaque‐forming cells using the local hemolysis in gel assay. The shift in affinity of anti‐hapten antibodies, that occurs with time after immunization, was parallelled by an analogous shift, at the cellular level, with regard to indirect plaque‐forming cells (PFC). Thus, there was a gradual decrease of the hapten concentration which was needed to suppress indirect plaque formation with time after immunization, indicating a gradual increase in the number of high affinity cells. No such shift was observed with cells causing direct plaque formation.Analogous studies were performed with hapten‐specific antigen‐binding cells of T and B origin by using hapten‐inhibition of rosette‐forming cells. Hapten‐specific antigen‐binding cells were present in both cell populations. Lymphocyte binding of haptenated red cells could be specifically inhibited by free hapten. It was found that antigen‐binding B lymphoid cells became gradually more susceptible to hapten inhibition with time after immunization, whereas no such change was observed in antigen‐binding T lymphoid cells. Possible reasons for this discrepancy are discussed, as well as the implications for these findings regarding the specificity and structure of the T cell receptors.