The humoral immune response of mouse bone marrow lymphocytes in vitro.

Mouse bone marrow (BM) small lymphocytes are shown to contain competent precursors for a primary haemolytic plaque forming cell (PFC) response to heterologous red blood cells and TNP in an in vitro culture system. Their response is dependent on T co-operative factors, which can be provided by irradiated spleen cells activated by concanavalin A or the supernatant of an allogeneic culture, added at the beginning or after 24 h of culture. The frequency of PFC precursors for the response to SRBC is found to be equal or higher in BM than spleen cultures. However, BM lymphocyte cultures stimulated by E. coli lipopolysaccharide show an increase of DNA synthesis but contain only few polyclonal PFC, in contrast to spleen.