Studies on the cellular basis of IgM immunological memory. The induction of antibody formation in bone marrow cells by primed spleen cells.

Immunological memory and antibody formation appear to be properties of different cell lines. This follows from a demonstration that cells from spleens of mice primed with sheep erythrocytes are capable of inducing normally unresponsive bone marrow cells to produce specific antibody. Primed spleen cells, taken from CBA or CBAT6T6 mice, were cultured for 5 or 6 days with an excess of bone marrow cells of the opposite chromosome type, and with antigen, in lethally irradiated, histocompatible mice. The tissue of origin of antibody-plaque-forming cells from the spleens of the irradiated mice was then identified from chromosome spreads of individual plaque-forming cells. After 5 days of culture, equal numbers of spleen and bone marrow cells were found producing antibody. At 6 days nearly all of the plaque-forming cells were from the bone marrow. Plaque-forming cells of bone marrow origin were also identified, using an immunogenetic technique, when semi-allogeneic mixtures of spleen and bone marrow cells were cultured together.