Absence of an association between mannose-binding lectin polymorphism and rheumatoid arthritis.

It has been proposed that mannose-binding lectin (MBL) interactions with agalactosyl forms of IgG immunoglobulins found in rheumatoid synovial fluid might lead to enhanced complement activation, an important mediator of the joint damage in rheumatoid arthritis (RA). In order to investigate this possible link between increased MBL-mediated activation of complement and perpetuation of rheumatoid synovitis, we have compared the frequency of an allelic form of MBL, known to be incapable of activating complement, in a group of hospital patients with severe RA and control subjects. No evidence was found to support an association between the presence of this MBL allele and protection from rheumatoid disease; genotype frequencies were similar in both groups. This suggests that complement activation via MBL-agalactosyl IgG complexes is unlikely to play a major role in the pathophysiology of RA.