Lymphocytotoxicity of anti-Klebsiella antisera in ankylosing spondylitis and related arthropathies: patient and family studies.

Antisera to certain isolates of Klebsiella pneumoniae have a specific lymphocytotoxic effect on the HLA–B27 bearing lymphocytes in 83% of B27 positive patients with ankylosing spondylitis and about 60% of patients with HLA–B27 positive Reiter's syndrome and asymmetrical peripheral arthritis. These findings indicate cross-reactivity between a Klebsiella antigen and a “modified” HLA–B27 or a closely associated structure in patients with ankylosing spondylitis and related arthropathies. Family studies indicate that the alteration in HLA–B27 is not a direct genetic effect.