IgD-Bearing Human Lymphocytes

Abstract

Abstract IgD is a class of immunoglobulin described, thus far, only in humans and constituting approximately 0.2% of all serum immunoglobulin (1–2). Although antibody activity has been ascribed to the IgD class of immunoglobulin, the biologic function of these molecules is unknown (3–10). We now report that a surprisingly large fraction of human peripheral blood lymphocytes bear surface IgD. Thus, a mean of 2.7% of lymphocytes can be shown to have membrane-associated IgD. This is approximately 18% of all lymphocytes bearing surface immunoglobulin. Materials and Methods. Heparinized venous blood from normal adult donors was sedimented in 6% dextran (Phamachem Corp., Bethlehem, Pa.) and the white cell-rich supernatant plasma incubated on rayon wool columns for 30 min at 37°C in an atmosphere of 95% air and 5% CO2. The erythrocytes in the effluent cell suspensions were lysed with ammonium chloride (11); the cells were then washed and resuspended in RPMI 1640 (Grand Island Biological Co., Rockville, Md.). The cell suspensions thus obtained consisted of 95% lymphocytes; the yield of lymphocytes was approximately 70%. Thymus and tonsil cell suspensions were prepared from fresh surgical specimens.