HLA-B27 associated cross-reactive marker on the cells of New Zealand patients with ankylosing spondylitis.

We have previously shown that antibodies raised in rabbits to certain enteric bacteria will specifically lyse, in a 51Cr release assay, the peripheral blood lymphocytes (PBL) of 80% of HLA-B27 positive patients with ankylosing spondylitis (B27+ AS+) but not the PBL of HLA-B27 positive normal controls (B27+ AS-). Other laboratories have been unable to reproduce these findings. This study was designed to ascertain whether this lack of reproducibility was due to a peculiarity of our B27+ AS+ patients or to technical difficulties in the complement mediated 51Cr release assay. We have shown in this blind study that the PBL of 16 out of 18 B27+ AS+ patients from a New Zealand population were lysed by our antisera but none of the PBL of 20 B27+ AS- normal controls were lysed. The phenomenon of 'cross reactivity' between certain enteric bacteria and B27+ AS+ PBL is not confined to the Sydney AS population.