Participation of immunoglobulin‐bearing lymphocytes in the production of macrophage migration inhibitory factor

The role of immunoglobulin‐bearing cells in the production of macrophage migration inhibitory factor (MIF) by tuberculin‐stimulated lymphocytes of guinea pigs, immunized with complete Freund's adjuvant, was studied. It was found that: (1) pretreatment of lymphocytes with rabbit anti‐guinea pig IgG (anti‐IgG) does not block antigen‐induced MIF production. (2) Passage of lymphocytes through double layer IgG‐anti‐IgG gelatin bead columns (the preparation of which is described) abolishes MIF formation by the eluted cells. Cells retained on the columns can be recovered and where shown to produce MIF, when stimulated by antigen. (3) Pulsing of lymphocytes with anti‐IgG, for 2 h at 37°C, results in MIF synthesis by the cells cultured in medium, in the absence of specific antigen. These findings indicate that cells bearing Ig or Ig fragments are either able to secrete MIF themselves, upon stimulation with antigen or anti‐IgG, or are required for MIF production by a different cell type.