Defective antibody production in patients with rheumatoid arthritis and bronchiectasis

Bronchiectasis (BR) occurs in about 3% of patients with rheumatoid arthriti s (RA). Defective antibody production is a rare but well-recognised cause o f both BR and inflammatory arthritis. We examined the hypothesis that subtl e specific antibody defects might play a role in the pathogenesis of BR ass ociated with RA. Identification of defects in antibody production is import ant because substantial benefits may be gained from immunoglobulin replacem ent. Specific antibody production was assessed in 20 patients with RA and B R, 20 with BR alone. 20 with RA alone and 20 healthy controls (all groups m atched for age and sex). All had normal total IgG, IgA and IgM and IgG subc lass levels. Specific antibody production was assessed by assay of antibodi es to representative polysaccharide and protein antigens. Subjects with sub protective titres were challenged with the appropriate vaccine. Defective a ntibody production was defined as a subprotective level despite immunisatio n. Three out of 20 patients with RA and BR had a defective IgG(2) response to the polysaccharide antigen, but normal responses to the protein antigen. All of the subjects in the BR alone or healthy control group had normal an tibody production. Two out of 20 patients with RA alone had defective produ ction of antibodies against both protein and polysaccharide antigens; both were receiving gold therapy, a recognised cause of functional antibody defe cts. It was concluded that some patients with RA and BR have functional ant ibody defects and may benefit from antibody replacement. An unexpectedly hi gh proportion of patients with RA alone also have functional antibody defec ts, possibly secondary to gold therapy.