Detection of Cells Secreting Antibodies more Reactive with an Alternate Structure than with the Immunizing Hapten

Abstract

An extension of hapten-specific plaque-forming cell procedures has been developed which involves coupling of sulfobenzeneazo-N-acetyl-l-tyrosyl azide with indicator erythrocytes. This new assay system has been used to study immune cell suspensions from rabbits immunized with simpler sulfobenzeneazo groups attached to carrier by diazonium coupling. The numbers of plaque-forming cells disclosed by the new assay were comparable to those for a standard system employing indicator red cells bearing sulfobenzeneazo groups homologous to those on the immunogen. Experiments with mixed indicator erythrocytes and with combined-coupled red cells revealed that the two different indicator systems detected mainly separate N-acetyl-l-tyrosyl moiety was lacking in the immunogen. The data the branched N-acetyl-l-tyrosyl moiety was lacking in the immunogen. The data have been interpreted in the light of current concepts of the nature of antigen receptors on antibody-forming cell precursors. The findings suggest that precursor cells can be activated which bear receptors better adapted to a determinant different than the immunizing hapten.