RELEASE AND ASSAY OF ANTIGEN-BINDING IMMUNOGLOBULIN FROM THE SURFACES OF LYMPHOCYTES OF UNSENSITIZED MICE

Abstract

SUMMARY A subpopulation of immunoglobulin (Ig) from the surfaces of lymphocytes of unsensitized mice which have been incubated with dinitrophenylated, radioiodinated homologous hemoglobin is released complexed specifically to the antigen. The complex was removed from the lymphocyte surface by metabolic turnover which occurs during short-term tissue culture and by limited proteolysis with trypsin. This observation represents direct evidence that a function of cell surface Ig is to combine with antigen. Seventy to eighty percent of antigen initially bound remains with the cell after 2 hr of tissue culture but most of this retained antigen is released by trypsin treatment; 85-90% of total bound antigen is released by this combined treatment. Most naturally released antigen is released by itself but a significant proportion is complexed to its Ig receptor. In addition, released receptor for antigen is capable of combining with its specific antigen.