Surface Immunoglobulins on Mouse Lymphoid Cells

Abstract Addition of 125I-labeled anti-immunoglobulin protein to cell suspensions from mouse thymus, spleen and thoracic duct lymph (TDL) resulted in labeling of surface immunoglobulins of lymphoid-like cells. Near-optimal conditions for cell labeling were established with varying anti-immunoglobulin concentrations and times of exposure. On the average 20.1% to 36.3% of TDL and spleen cells labeled under such conditions, whereas thymus cells labeled less heavily (0.3% to 3.7%) with identical materials. Normal rabbit sera (NRS) or anti-immunoglobulin absorbed with purified immunoglobulins produced essentially no labeling. The total heavy chain labeling on TDL and spleen cells exceeded light chain labeling (64.6% vs 31.8% and 79.8% vs 33.0%, respectively). This might suggest that labeled cells had multiple surface heavy chain determinants or that the anti-heavy chain antibodies cross-reacted with an unidentified immunoglobulin-like surface antigen. There was increased labeling with TDL suspensions from neonatally thymectomized mice (65% with anti-light chain). This was consistent with the hypothesis that primarily non-thymus-derived cells were labeled by these techniques.