Comparative Study of Cytotoxic T‐Lymphocytes and Producers of the Macrophage Migration Inhibition Factor (MIF) in the H‐2 System

Abstract

Comparative study of two T‐cell subpopulations, killers and MIF producers, immune to H‐2 antigens, was performed using the in vitro micro‐techniques of cell‐mediated cytolysis and inhibition of macrophage migration. T‐dependence of MIF production was shown in this system by lymphocyte separation onto T‐ and B‐cells and by inactivation of MIF producers with anti‐θ serum. At least part of MIF producers appeared to be more sensitive than killers to the action of anti‐κ antibodies in the presence of complement. Production of MIF as compared to the cytotoxic activity was revealed in regional lymph node cells earlier and preserved longer after immunization with allogeneic tumour cells. Immune lymph node cells were shown to produce MIF when incubated with spleen cells of congenic and recombinant strains of mice possessing either private or public H‐2 specificities of the immunizing complex, but they did not produce MIF when incubated with syngeneic spleen cells. Removal of killers by absorption on the relevant target cells did not reduce the ability of non‐adherent lymphocytes to produce MIF. Unlike cytotoxic activity, MIF production is inhibited by pre‐treatment of immune lymphocytes with pronase. The data obtained are indicative of essential differences in effector T‐cell subpopulations which exert the cytotoxic effect and produce MIF in the H‐2 system. The implications of these data for studies on T‐cell differentiation under the action of H‐2 antigens are discussed.