Oral dosing of rats with OM-89 results in the appearance of specific OM-89 antibodies of the IgG2a isotype : Possible significance in the treatment of rheumatoid arthritis

• Published in: International journal of immunopharmacology 1997-09, Vol.19 (9-10), p.569-572
• Main Authors: PHIPPS, P. A, MOORE, A. R, GOWLAND, G, KHANAM, A, WILLOUGHBY, D. A
• Format: Article
• Language: English
• Subjects: Administration, Oral; Animals; Antibodies, Bacterial - blood; Antibody Specificity; Antigens, Bacterial - administration & dosage; Antirheumatic Agents - administration & dosage; Arthritis, Rheumatoid - immunology; Arthritis, Rheumatoid - therapy; Biological and medical sciences; Escherichia coli - immunology; Heat-Shock Proteins - immunology; Humans; Immune Tolerance; Immunoglobulin G - blood; Immunoglobulin M - blood; Immunomodulators; Immunosuppressive Agents - administration & dosage; Male; Medical sciences; Pharmacology. Drug treatments; Rats; Rats, Wistar; T-Lymphocytes - immunology
• ISSN: 0192-0561; 1879-3495
• DOI: 10.1016/S0192-0561(97)00053-2

OM-89 is a glycoprotein-rich extract of Escherichia coli shown to be effective in the treatment of rheumatoid arthritis (RA). It has been reported that oral dosing of animals results in the appearance of specific OM-89 antibodies. In the current study we have investigated some of the immunoglobulin isotypes that may be involved. OM-89 antibodies of IgG1, IgG2a and IgM isotypes were measured by ELISA in serum from rats dosed three times a week for 3 weeks at 4 or 40 mg kg(-1). The results showed a small but significant rise in IgM and a greater rise in IgG2a. The possibility that antigens within OM-89 (e.g. hsp65) may have homology with antigens involved in RA raises the possibility that OM-89 antibodies, particularly of the IgG2 class, may block pathogenic antigens from being recognized by T cells.