T and B lymphocytes in the marmoset: a natural haemopoietic chimera.

The thymus-derived (T) lymphocyte and bone marrow-derived (B) lymphocyte populations of the marmoset were characterized using specific cell surface markers Approximately 85% of the thymocyates formed rosettes with neuraminidase-treated sheep erythrocytes (En). The percentage (approximately 69%) of peripheral blood lymphocytes (PBL) forming rosettes with En was the same as that which stained with fluorescently labelled goat anti-marmoset thymocyte serum (ATS). These two assays identified the same cell population since treatment of cells with ATS and complement resulted in a concomitant decrease in En rosette formation. Marmoset PBL also formed rosettes with human erythrocytes sensitized with antibody and complement (HEAC); since the percentage (approximately 20%) HEAC rosette was the same as that of cells stained with fluorescently labelled goat anti-marmoset IgG, these cells were considered to be B cells. A small percentage of cells (approximately 1-5%) possessed both types of receptors. The mean percentages of T and B cells present in PBL of single-born, presumably non-chimeric animals, were the same as that of iso-sexual and heterosexual chimeras.