Production of MIF-like supernatants by rheumatoid arthritis lymphocytes stimulated by immunoglobulin G.

Patients with rheumatoid arthritis (RA), patients with positive tuberculin (PPD) skin-tests and controls were studied. The lymphocytes from these groups were cultured in serum-free medium to obtain cell-free supernatants. These lymphocyte cultures were pre-incubated with the appropriate antigen or reconstituted after removal of the cells. Supernatants from RA lymphocytes stimulated in vitro by IgG induced an inhibition of the leucocyte migration, as well as the supernatants from tuberculin-sensitized lymphocytes. However, supernatants from non-RA lymphocytes or tuberculin-unsensitized lymphocytes did not show such an inhibition. These MIF-like supernatants have been studied by Sephadex G-100 gel filtration. A MIF activity has been found for PPD and IgG supernatants between the chymotrypsinogen (MW 23,000) and the lysozyme (MW 17,000). This seems to agree with the classical region where MIF can be usually isolated.