Migration of antibody-forming cells and antigen-sensitive precursors between spleen, thymus and bone marrow.

The appearance of 19S and 7S antibody-forming cells (producers) in mice following a single i.p. injection of sheep erythrocytes, and their recirculation between spleen, thymus and marrow, were studied by the direct and indirect Jerne plaque techniques. The appearance and distribution of antigen-sensitive precursor cells (memory cells) in the same tissues were determined by transferring aliquots of thymus, marrow and spleen cells to irradiated recipients, restimulating with antigen, and counting the plaque-forming cells (PFCs) in the recipient spleens. 2-ME sensitive and 2-ME resistant serum antibodies in donors and recipients were also titrated. 19S antibody production in mice reached a peak 4 days after antigen and declined rapidly thereafter. Direct PFCs were found in the spleen, but not in thymus or marrow. These cells probably do not recirculate, at least not within their life-span as 19S antibody producers. Production of 7S antibody reached a peak 7 days after immunization. Indirect PFCs were most numerous in the spleen at this time and persisted in the body for several weeks. These cells probably recirculate since increasing numbers were found in the thymus and marrow with increasing intervals after immunization. The appearance and distribution of antigen-sensitive precursor cells showed a pattern similar to that of the 7S producers, suggesting that they recirculate in a similar manner.