RABBIT LYMPHOID-CELLS .2. ANTI-ALLOTYPE ANTISERA, LIPOPOLYSACCHARIDE AND OTHER BACTERIAL AND FUNGAL MITOGENS AS PROBES FOR IDENTIFICATION OF B-CELL SUBPOPULATIONS

Abstract

Removal of adherent cells or complement-mediated killing of rabbit thymus lymphocyte antigen (RTLA) bearing rabbit T [thymus-derived] lymphocytes did not abolish the responsiveness (increased thymidine incorporation) of lymphoid cells to antibody against immunoglobulin allotype, Nocardia water-soluble mitogen (NWSM), pneumococcal polysaccharide SIII (PPSIII), Salmonella abortus lipopolysaccharide (LPS), lipid A conjugated to bovine serum albumin and a crude preparation containing C polysaccharide from the cell wall of Diplococcus [Streptococcus] pneumoniae. Isologous and heterologous antisera, directed against different portions of the Ig [immunoglobulin] receptor, differed in their capacity to enhance thymidine incorporation. The difference in mitogenicity of these antisera was discussed in terms of the accessibility of cell-bound Ig receptor sites. Spleen cells, responsive to anti-allotype (Ab4) antiserum and B[bone marrow-derived]-cell mitogens, NWSM and PPSIII, were characterized by velocity sedimentation. The mean volume of NWSM- and PPSIII-responsive cells was larger than that of the cells responsive to anti-allotype antiserum. Fractionation of spleen cells on glass bead columns yielded a population of non-adherent cells which were 2-6 times as responsive to anti-Ab4 antiserum as the original spleen cell suspension. The responsiveness of peripheral blood lymphocytes to anti-Ab4 antiserum was significantly greater than that of spleen cells. Spleen cells were more responsive to PPSIII than were cells from the peripheral blood, the popliteal and the mesenteric lymph nodes.