title: Synovial fluid from rheumatoid arthritis patients induces polyclonal antibody formation in vivo.
abstract: Our previous studies demonstrated the presence of a T-cell replacing factor in the synovial fluid (SF) of patients with rheumatoid arthritis (RA) and that RA-SF can activate, selectively, the induction of IgG2b antibody secreting cells in lipopolysaccharide (LPS)-pretreated mouse spleen cell cultures. In the present study the effect of RA-SF was tested in vivo in mice. Injection of the polyclonal activator LPS induced the production of IgM and IgG3 secreting cells in normal mice. However, the addition of RA-SF led to a selective increase in the production of IgG2b with a peak response on day 5 and IgG1 plaque-forming cells (PFC) with a peak on day 7. Neither the IgG2b nor IgG1 responses were caused by specific immunity against heterologous proteins present in RA-SF, as injection of in vitro inactive RA-SF samples did not induce PFC. The effect on B cells of RA-SF was further evaluated by injection of RA-SF in combination with LPS to the Xid B-cell deficient CBA/N mice. RA-SF had identical effects in CBA/N as in normal mice. The biological implication of these findings is discussed. Our earlier results support the idea that B cells are endogenously activated in RA patients. We have speculated that this activation is caused by the B-cell differentiation factor which is present in SF. Therefore, we also tested whether RA-SF could influence antibody-forming cells in mice that spontaneously develop autoimmunity. We found that injection of RA-SF alone, in the absence of any other activating substance, induced a very marked increase of IgG producing cells in (NZW x NZB) F1 hybrid mice. From a relatively high background level the RA-SF could still induce an up to 100-fold increase in the numbers of PFC in spleens of such mice.
authors.affiliation: Department of Immunology, University of Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Abedi-Valugerdi
authors.forename: A
authors.initials: A
authors.lastname: Ridderstad
authors.forename: H
authors.initials: H
authors.lastname: Ström
authors.forename: E
authors.initials: E
authors.lastname: Möller
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007075:Immunoglobulin M / Q000096:biosynthesis; D015847:Interleukin-4 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D013582:Synovial Fluid / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015850:Interleukin-6; D008070:Lipopolysaccharides; D015847:Interleukin-4