Role of macrophages in tumour immunity. I. Co-operation between macrophages and lymphoid cells in syngeneic tumour immunity.

Abstract

Macrophages from DBA/2 mice hyperimmunized with irradiated syngeneic L5178Y or SL2 lymphoma cells inhibited the growth of these cells in vitro and killed them within 48 hours of culture. The reaction was immunologically specific. Non-immune macrophages could be rendered capable of immunologically-specific growth inhibition of target cells in vitro (arming) (a) by direct contact of hyperimmune lymphoid cells and macrophages, and (b) by incubating macrophages with a specific macrophage-arming factor (SMAF) derived by incubating spleen cells from singly immunized mice with irradiated lymphoma cells. Singly immunized spleen cells did not arm macrophages by direct cell-to-cell contact. A temporal relationship was seen between the presence of immune macrophages in hyperimmunized mice and the ability of the spleen cells to arm normal macrophages. Furthermore, macrophages could be armed in vivo by a single i.p. injection of hyper immune spleen cells. The presence of arming factors cytophilic for macrophages, but not for cells of non-macrophage origin, is briefly discussed.