Induction of bone resorbing activity by normal and rheumatoid arthritis T cells

We studied the role of T cells in the production of osteoclast activating factor (OAF) using anti-CD3 MAb as a specific T cell activator. OAF activity was totally inhibited by anti-IL-1 beta. Peripheral blood mononuclear cells (PBMNC) from normal subjects produced more OAF than did PBMNC from rheumatoid arthritis (RA) patients. Mononuclear cells (MNC) from RA synovial fluid produced less OAF than did RA peripheral blood. We conclude that (i) specific T cell stimulation induces OAF production which may be attributed to interleukin 1 (IL-1) activity, (ii) the inhibition by anti-IL-1 beta of OAF production following anti-CD3 stimulation suggests that the T cell signal is being transmitted to the macrophage, and (iii) RA MNC are deficient in T cell-mediated OAF production.