Abstract
We have previously shown that antisera raised in rabbits to certain enteric cross reactive strains of bacteria are capable of specifically lysing the peripheral blood lymphocytes of HLA-B27 positive patients with ankylosing spondylitis (B27+ AS+). We now report that bacteria with cross reactive antigenic determinants are found in the bowel flora of all of 52 B27+ AS+ patients but in only one of 50 HLA-B27 positive normal controls (B27+ AS-). These organisms are functionally similar to the cross reactive enteric bacteria originally reported. They are not confined to a particular genus or species and their cross reactive serological nature appears to be a property shared by all enteric organisms isolated from B27+ AS+ patients. Organisms with these properties have been shown to persist in the bowel flora of 14 B27+ AS+ patients followed up for more than one year.