Studies on antibody affinity at the cellular level. Correlation between binding properties of secreted antibody and cellular receptor for antigen on immunological memory cells.

Heterogeneity with regard to affinity of anti-hapten antibody was demonstrated at the cellular level in mice. The heterogeneity was shown at the level of single antibody-forming cells using hapten inhibition of hemolytic antibody plaque formation as a measure of affinity. The affinity increased with time after immunization. A high antigen dose initially resulted in relatively low affinity antibody production as compared to the affinity of the antibody production in animals immunized with a low dose. Affinity specialization of immunological memory cells was demonstrated, since it was possible to specifically fractionate such cells with regard to affinity on hapten-protein-coated plastic bead columns. High affinity memory cells showed a higher tendency to become retained in the columns than did low affinity memory cells. The data in a direct way demonstrate that memory cells carrying membrane-associated receptors of a certain affinity for the antigen are determined to release antibody of a similar affinity after stimulation with antigen.