Requirement for adherent cells in the primary and secondary immune response in vitro

Treatment of spleen cells with iron powder, followed by removal of the iron with a magnet, was found to be a simple and reliable method for obtaining a pópulation of non‐adherent cells, which does not give an antibody response against heterologous red cells in vitro . It was possible to reconstitute the antibody response to 40 ‐ 90% of that obtained with untreated cells by addition of irradiated or non‐irradiated adherent spleen cells. The secondary response was also depressed by treatment with iron and it could be completely reconstituted with adherent cells from normal mice. Removal of adherent cells also caused a depression of spontaneous cell proliferation, which could be reconstituted by addition of adherent cells. Comparative kinetic studies on cell proliferation and antibody response indicated that the adherent cells are necessary for a normal cell proliferation and that they do not act by breaking down the antigen. This conclusion was further supported by the finding that an immune response against a soluble sheep red cell antigen was also dependent on adherent cells.