Inhibition of antibody-dependent allergic autocytotoxicity in rheumatoid arthritis by OM-89

Rheumatoid arthritis (RA) is a disease of multiple etiologies and clinical evidence suggests that a separate variant called "allergic arthritis" induced by food antigens could exist. A missing link in the confirmation of such an observation is a relative lack of a reliable in vitro assay which can confirm the in vivo oral ingestion challenge. Therefore, white blood cells (WBC) from 33 rheumatoid arthritis patients were separated and their disintegration was measured in the presence of specific IgE RAST positive sera and gluten-gliadin antigens. This assay was called the antibody-dependent allergic autocytotoxicity (ACT) test which represents an equivalent of an oral ingestion challenge with food antigens. Control WBC expressed 10-45% disintegration as compared to 75-95% in RA. Preincubation of WBC with OM-89 (immunomodulating fractions of Escherichia coli, OM Laboratories Ltd, Geneva, Switzerland) inhibited significantly antibody-dependent ACT in a dose-related manner (P less than 0.001) in our patients.