Antibodies to Brewer's Yeast in Rheumatoid Arthritis.

Antibodies to brewer's yeast or anti-Saccharomyces cerevisiae antibodies (ASCA) have been detected in 70% of patients with Crohn's disease and have become a part of the evaluation of a patient for Crohn's disease. Prior evaluation of these antibodies in rheumatoid arthritis have been inconsistent. In an initial small study, the levels of antibodies were elevated but not statistically significant. In a second large study from China, 40% of rheumatoid arthritis patients were positive for immunoglobulin A (IgA) ASCA and 20% positive for immunoglobulin G (IgG) ASCA. Our study was inspired by the observation that several seronegative patients with rheumatoid arthritis were positive for ASCA antibodies. Between January 1, 2016 and January 1, 2018, a total of 241 patients with clinical rheumatoid arthritis were evaluated for antibodies to IGA and IGG ASCA, rheumatoid factor, cyclic citrullinated peptide (CCP), and antinuclear antibody (ANA). Our results indicate that 158 (66%) of these patients were positive for ASCA; 70 (29%) of these patients were positive for ASCA but negative for other serologies; 62% of the patients were positive for rheumatoid factor. Our results also indicate that the percentage of rheumatoid factor (95%) and CCP positive (78%) patients in the ASCA negative group was higher than the percentage of rheumatoid factor positive (49%) and CCP positive (37%) patients in the ASCA positive group, suggesting serologic differences between the two groups. Only 4% of the rheumatoid patients were negative for all the evaluated serologies. The possible role of mannan, a mucopolysaccharide from the cell wall of Saccharomyces cerevisiae (S. cerevisiae) in producing rheumatoid arthritis is discussed.