ANTI-IGG AUTOANTIBODIES AND POSSIBLE IMMUNE REGULATORY MECHANISMS IN PATIENTS WITH PULMONARY TUBERCULOSIS

Setting: Anti-Ig antibodies are known to have important clinical and b iological implications. Objectives: To determine naturally occurring a nti-F(ab')2 gamma and anti-Fc gamma antibodies in patients with pulmon ary tuberculosis (PTB) in relation to various clinical manifestations and human leukocyte antigen (HLA). Design: Antibodies to F(ab')2 and F c portions of IgG were detected in the sera of normal healthy individu als (n = 41), patients with pulmonary tuberculosis (n = 50) and their household family contacts (n = 20) using an enzyme immune assay (EIA) system. Results: As compared to controls (0.110 +/- 0.01 optical densi ty [OD]), the levels of anti-F(ab')2 gamma were significantly increase d in PTB patients (0.998 +/- 0.08 On, P < 0.0001) and in their contact s (0.486 +/- 0.04 OD, P < 0.001) suggesting that the occurrence of the se autoantibodies is related to infection/exposure to Mycobacterium tu berculosis. Anti-F(ab')2 gamma antibodies were significantly increased in both sputum positive and negative patients (P < 0.0001) and no dev iation was observed between these two groups. The levels of these anti bodies were positively correlated with disease severity assessed by ch est X-ray. The drug failure patients had higher activity of anti-F(ab' )2 gamma than drug responders and no impact of anti-tuberculosis chemo therapy was observed. A statistically significant increase of anti-F(a b')2 gamma levels (1.25 +/- 0.21 OD) was observed in HLA-DR2 positive patients as compared to the DR2 negative groups (1.02 +/- 0.09 OD), P < 0.01. No deviation was observed in the levels of anti-Fc gamma level s between controls and any group of PTB patients. Conclusion: The pres ent data suggests that the elevated levels of anti-F(ab')2 gamma antib odies in PTB patients represent an anti-idiotypic antibody response to anti-M. tuberculosis antibody caused by an immune imbalance following M. tuberculosis infection.