Takayasu's arteritis: Role of Mycobacterium tuberculosis and its 65 kDa heat shock protein

Background: Mycobacterium tuberculosis has been implicated in the pathogenesis of Takayasu's arteritis (TA). Recently, its 65 kDa heat shock protein (HSP) has been implicated in the pathogenesis of other autoimmune diseases. We thus decided to study humoral immune response to Mycobacterium tuberculosis antigens in patients with TA. Aim: To study humoral immune response to Mycobacterium tuberculosis and its 65 kDa HSP, a putative autoantigen, in patients with TA. Methods: Antibodies to sonicated Mycobacterium tuberculosis extract (MBA) and its recombinant 65 kDa protein were measured using ELISA in 36 patients with TA and 35 healthy controls. Levels exceeding mean +2 S.D, of the controls were taken as positive responses. Results: Abnormally elevated levels of IgG, IgM and IgA antibodies against MBA were present in 6, 20 and 7 patients respectively whereas those against r65 kDa protein were present in 6, 7 and 33 patients, respectively. Though the levels of IgG antibodies were also elevated, those of IgM and IgA antibodies were elevated to a greater extent. Conclusions: Patients with TA have heightened immune response to Mycobacterium tuberculosis antigens, in particular to its 65 kDa HSP, suggesting that this organism may have a role in the immunopathogenesis of this disease.