Defective Solubilization of Immune Complexes and Activation of the Complement System in Patients with Pulmonary Tuberculosis

Association between inherited deficiencies of the complement components and immune complex disease indicates the importance of the complement system in the handling of circulating immune complexes. High levels of circulating immune complexes are seen in pulmonary tuberculosis. This study is, therefore, aimed to look at the concentration of circulating immune complexes, the status of complement-mediated immune complex handling, and the extent of complement activation in untreated pulmonary tuberculosis compared to treated pulmonary tuberculosis patients and healthy controls. High immune complex levels, decreased complement-mediated solubilization, and increased activation of the complement system were observed in untreated tuberculosis patients. The results obtained from the present study suggest that complement mediated solubilization is less in patients with tuberculosis, and this defective solubilization is likely to take part in a vicious cycle involving immune complex deposition and complement activation and, thus, may lead to disease progression depending on the nature of the defect.