Igm and igg anti‐f(ab )₂ antibodies in rheumatoid arthritis and systemic lupus erythematosus

Abstract

Radioimmunoassays for anti-F(ab')z antibodies, which feature the use of goat anti-human Fc antibody for correcting potentiation of IgM anti-F(ab')z antibody titers by endogenous IgM anti-Fc antibodies (rheumatoid factors), are described. Individuals with classic rheumatoid arthritis had significantly more IgM anti-F(ab')2 antibody (P < 0.001) and IgG anti-F(ab')2 antibody (P = 0.05) than did individuals with systemic lupus erythematosus or normal volunteers. There is some similarity in patterns of isotype distribution of anti-F(ab')z antibodies and rheumatoid factors.

Anti-F(ab')2 antibodies in thrombocytopenic patients at risk for acquired immunodeficiency syndrome.

“…In addition, since AIDS is a disorder of immune regulation, it is likely that these anti-F(ab')2 antibodies, which are present at low levels in some normal control subjects (12,16,23), have lost their immunoregulatory control mechanisms. A disorder of down regulation of anti-F(ab')2 antibody production thus might reflect perturbation of the T cell-B cell network by the AIDSassociated retrovirus.…”

The specificity of antibodies to the F(ab′)2 fragment of human IgG

“…Isotype-specific radioimmunoassays (RIA) for IgG anti-F(ab')z were carried out as described previously (5 Immune complexes were prepared from tetanus toxoid obtained from the Massachusetts Department of Public Health, Boston. The material was radiolabeled with '"Na by the method of Fraker and Speck (18) and moved on SDS-PACE in the presence of 2-mercaptoethanol as a major component at approximately 180,000 daltons.…”

Anti-Fab antibodies in humans. Predominance of minor immunoglobulin G subclasses in rheumatoid arthritis.

“…Since then aFABA have been shown to have varying specificities for different portions of the Fab and F(ab')2 molecule and to circulate as immune complexes. Additionally, they may also be present in other autoimmune diseases, chronic infections, after immunization, or in some normal individuals (11)(12)(13)(14)(15).…”