Is a Klebsiella plasmid involved in the aetiology of Ankylosing Spondylitis in HLA-B27-positive individuals?

Abstract

The possibility that plasmid genes, carried by enteric organisms previously indirectly implicated as disease agents, play a role in the pathogenesis of Ankylosing Spondylitis (AS) was explored. A particular Klebsiella isolate (K21) previously found to cross-react with cells from HLA-B27 positive (B27+) patients with AS, but not with cells from normal individuals, was found to contain a plasmid(s). This coded for the organism's ability to produce a factor which could modify B27+ normal cells (AS-) rendering them lysable by the anti-Klebsiella serum. Curing of this isolate resulted in the loss of the plasmid concerned and a loss of ability of its culture filtrate to modify B27+ lymphocytes of clinically healthy subjects. When plasmids from K21 were transferred to a plasmid free laboratory strain, E. coli JP995, the recipient strain acquired the ability to elaborate modifying factor. These data suggest that plasmids, harboured by some enteric bacteria, and their products, may be implicated in modifying cells bearing certain Major Histocompatibility Complex genes, and that such modification may be an important factor in the pathogenesis of a number of diseases including the seronegative arthropathies.