Ankylosing spondylitis with selective IgA deficiency and a circulating anticoagulant.

A patient with ankylosing spondylitis was found to have selective IgA deficiency and a non-heparin, immediate-acting antithrombin (antithrombin V). T cells were decreased, and serum IgG was increased. In vitro synthesis of IgG by peripheral blood lymphocytes was very high. This association of ankylosing spondylitis with the T cell and protein abnormalities is probably fortuitous but does demonstrate that severe spondylitis may evolve in the absence of IgA.