Autoantibodies to Tumor Necrosis Factor in Patients with Active Pulmonary Tuberculosis.

BACKGROUND: Tumor necrosis factor (TNF) plays an important role in immune responses to the causative agent of tuberculosis, Mycobacterium tuberculosis. Additionally, TNF can also mediate many negative disease manifestations. The aim of this study was to assess the contribution of anti-TNF autoantibodies to the pathogenesis of active pulmonary tuberculosis (TB). METHODS: The levels of anti-TNF autoantibody classes and subclasses were determined by applying enzyme-linked immunosorbent assays (ELISAs). The levels of TNF and of its soluble receptors were also evaluated using commercial ELISA kits. RESULTS: The levels of both types of soluble TNF receptors were lower patients with TB than in healthy donors. Patients with TB had higher titers of immunoglobulin (Ig)G class and IgG3 subclass anti-TNF autoantibodies in comparison with healthy donors. Patients who had a disseminated TB infection had higher TNF level and IgG, IgG1 and IgG3 autoantibody titers compared with patients who had a localized TB infection. CONCLUSIONS: Changes in the titers of anti-TNF autoantibody classes and subclasses were noted in patients with TB, suggesting their possible contribution to the disease pathogenesis of TB.

Production of pure fractions of immunoglobulin G subclass autoantibodies against tumor necrosis factor.

Autoantibodies directed against cytokines are important effector molecules regulating the biological activity of cytokines. There is experimental evidence indicating that autoantibodies belonging to different immunoglobulin G (IgG) subclasses may have different functional activity. The purpose of this work was to develop a protocol for the purification of fractions of IgG subclass antibodies directed against tumor necrosis factor (TNF). We developed a series of steps, including gel filtration, positive and negative affinity chromatography, and ultrafiltration, to achieve this goal. Our protocol purified IgG subclass autoantibodies directed against TNF from a human immunoglobulin preparation. The isolation of these anti-TNF autoantibodies will enable evaluation of the effect of TNF-specific antibodies on TNF biological activity. Our newly developed technique for purifying subclasses of anti-TNF autoantibodies may be important for both basic research on the functional activity of these autoantibodies and for clinical immunology.