title: Biological characterization of T cell-replacing factor in the synovial fluid of rheumatoid arthritis patients.
abstract: The synovial fluid of patients with rheumatoid arthritis (RA) contains a biologically active factor which has the ability to replace T cells for the induction of antibody secretion by human blood lymphoid cells stimulated by pokeweed mitogen (PWM) in vitro. This factor, which will be referred to as RA-SF (synovial fluid), also has the capacity to act as a B cell-stimulatory factor of mouse splenic lymphocytes in the presence of lipopolysaccharide (LPS). Using a test system developed for the definition of interleukin 4 (IL-4), which is a B cell-stimulating lymphokine which preferentially activates the synthesis of selected Ig classes in mouse lymphoid cells, we have shown that RA-SF has properties similar to IL-4 in that it induces differentiation of antibody secretion in the LPS-pretreated mouse cell, but unlike IL-4, which gives IgG1 and IgE, it selectively induces IgG2b synthesis. The present study demonstrates that RA-SF has a biological activity that is reminiscent of other B cell-stimulating mouse lymphokines, but it is biologically distinct from IL-2, IL-4, and IL-5. Recent data also indicate that it is distinct from gamma interferon (IFN-gamma). Therefore, we conclude that the biological activity of RA-SF has properties in common with a T-cell replacing (TRF) and B-cell differentiation factor (BCDF) and probably represents yet another biological activity which so far lacks an experimental counterpart. The relevance of this factor for autoantibody synthesis is discussed.
authors.affiliation: Department of Clinical Immunology, Huddinge Hospital, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Möller
authors.forename: H
authors.initials: H
authors.lastname: Ström
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001681:Biological Assay; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000502:physiology; D015847:Interleukin-4; D015848:Interleukin-5; D007378:Interleukins / Q000502:physiology*; D008222:Lymphokines / Q000502:physiology*; D051379:Mice; D013582:Synovial Fluid / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D007376:Interleukin-2; D015848:Interleukin-5; D007378:Interleukins; D008222:Lymphokines; D015847:Interleukin-4