The modification of HLA-B27-positive lymphocytes by the culture filtrate of Klebsiella K43 BTS 1 is a metabolically active process.

The culture filtrate of some bacteria contains a modifying factor which specifically interacts with the cells of HLA-B27-positive normal individuals (BS+ AS-); this modification results in a serologically detectable change similar to that seen on the cells of patients with ankylosing spondylitis (B27+ AS+). Puromycin, 5-azacytidine, actinomycin D, cyclosporin A, dexamethasone, indomethacin, colchicine, quinacrine, chlorpromazine but not tunicamycin can effectively inhibit the in vitro modification of HLA-B27-positive lymphocytes from normal individuals. These studies suggest that a number of different metabolic pathways may be involved in the modification of B27+ AS- lymphocytes by certain enteric antigens.