Parallel tubular structures in T,B and null lymphocyte subpopulations.

T, B and Null lymphocyte-enriched subpopulations were isolated by means of sheep red blood cell (E SRBC) sedimentation and nylon wool adherence. In these subsets the proportion of Fc receptor-bearing cells was determined by the antibody-coated human and ox erythrocyte rosette assays (EA Hu and Ox). In the T-cell fraction the proportion of Fc-bearing lymphocytes was dependent on the procedure by which the sheep erythrocytes were removed from the E SRBC rosette-forming cells. Mechanical vibration resulted in considerably higher percentages of EA rosette-forming cells (EA-RFC) than osmotic shock or lysis with ammonium chloride. In all three procedures the number of EA Hu-RFC was slightly higher than the number of EA Ox-RFC. In the B-cell fraction the proportion of EA Ox-RFC was higher than that of EA Hu-RFC, mean values 43 and 33%, respectively. In the Null cell fraction the reversed was seen: mean values 54% EA Hu-RFC and 45% EA Ox-RFC. In all three lymphocyte fractions the majority of the EA-RFC contained parallel tubular structures and/or associated amorphous granules. Non-Fc receptor-bearing lymphocytes only occasionally showed parallel tubular structures or the amorphous granules.