Immunological activities of rat lymphocytes. I. Mitogenic responses and surface markers of lymphocytes from normal, thymectomized and B rats.

Lymphocytes from the peripheral blood, thoracic duct, spleen and lymph nodes of normal, thymectomized (TX) and thymectomized lethally irradiated marrow reconstituted (TXBM or B rats) Lewis rats were studied for their ability to proliferate in vitro in the presence of Con A or PHA. At the same time the lymphoid tissues of these animals were examined for the presence of B cells or T cells by immunofluorescence staining with antiserums to rat immunoglobulins or rat brain antigens (ARBS), respectively. The specificity of ARBS fort T cells was first established in both cytotoxicity and immunofluoresecnce studies with thymocytes as well as pruified T and B cells. In various lymphoid tissues from TX and B rats, cells carrying brain antigens were found which were unable to respond to Con A and PHA. Thymectomy has a lesser effect on the response to Con A that to PHA; this was particularly true in the thoracic duct where, following thymectomy, lymphocytes continued to respond to Con A but lost their ability to respond to PHA. This suggests that the response to PHA and Con A may belong to different cells' subsets but that the ability to respond to either one of these mitogens may be impaired in cells carrying known T cell markers.