Presence of Antibody-Forming Cell Precursors in the Mouse Adherent Spleen Cell Population

It is generally accepted that primary in vitro immunization of mouse spleen cells involves the synergistic participation of at least three different cell types (for reviews see 1 and 2). The initial separation of mouse spleen cells into two populations on the basis of their selective adherence to plastic culture dishes was reported by Mosier (3). Neither the adherent nor the non-adherent sub-populations, when cultured in vitro, respond to sheep erythrocytes (SRC).1 When these two subpopulations are recombined, the response to SRC is restored. It was later established that the non-adherent cell population contains both bone marrow- (B) and thymus- (T) derived lymphocytes. Although the non-adherent population contains T-helper cells and precursors to the plaque-forming cells (P-PFC), its nonresponsiveness is due to the lack of accessory cells. Restoration of the responsiveness of non-adherent cells by the addition of adherent cells has led to the assumption that the adherent cell monolayer provides little other than accessory cell function.