Allelic and Class Exclusion of Membrane-Associated Immunoglobulins of Human Lymphocytes

Data from several sources indicate that the immunoglobulin (Ig) found within the cytoplasm of the individual lymphocyte or plasma cell is of a single allotype and class (1, 2). Ig antigens have also been found in association with the plasma membranes of 5 to 20% of human peripheral blood lymphocytes; many of the bound Ig molecules are believed to be antigen receptors (3–7). The present experiments were designed to establish whether the genic restrictions that have been demonstrated for cytoplasmic Ig are true for membrane Ig of human peripheral lymphocytes. This information is important both to confirm the clonal nature of lymphocytes, and to determine at what level of the immune response genetic restrictions occur. Membrane Ig was detected by the mixed antiglobulin technique (immunocytoadhesion) in which human lymphocytes, after incubation with an antiglobulin, are reacted with Ig-coated indicator red cells (3, 8).