Effect of klebsiella capsular antisera on lymphocytes from patients with ankylosing spondylitis

The cytotoxicity of klebsiella capsular antisera for lymphocytes from 10 HLA B27-positive patients with ankylosing spondylitis and eight B27-negative normal control subjects was examined. None of the antisera was cytotoxic for lymphocytes from nine patients but several antisera were cytotoxic for the lymphocytes from one patient. There were no differences between the results obtained with lymphocytes from the nine patients and those with lymphocytes from the normal controls. If klebsiella carriage is important in the pathogenesis of ankylosing spondylitis, the results of this investigation suggest that the capsular antigen is probably not involved.