Requirement for T cells in the production of migration inhibitory factor

Abstract

The question whether B lymphocytes are capable of being activated by antigen in the absence of functional T cells was investigated in a model that excludes participation of T cells by virtue of an immune response gene restriction. Strain 2 guinea pigs are capable of responding to immunization with DNP PLL, whereas strain 13 animals are not. In the present experiments, animals of both strains were immunized with DNP PLL complexed to ovalbumin (DNP PLL Ova) under conditions in which equal titers of antibodies to DNP were produced by both strains. The failure of T cells of strain 13 animals to respond to DNP PLL was confirmed by the virus plaque assay. While spleen cells from both strains produced MIF after stimulation with DNP PLL Ova, in response to DNP PLL only strain 2 spleens were able to produce MIF. Cells from neither strain could be activated by DNP guinea pig albumin to produce MIF. The authors conclude that B lymphocytes are incapable of being stimulated by antigen in the absence of T cells, and that MIF production is a thymus dependent response. While the results indicate that MIF production is a valid qualitative assay for T cell competence, since MIF can be produced by B and T cells, the degree of migration inhibition cannot be regarded as a quantitative measure of T cell function.