C2 and tuberculosis: Using the Magpix multiplex cytokine assay, plasma levels of complement components (C2, C3, C3b/iC3b, C4, C4b, C5, C5a, C1q, MBL) and regulatory proteins (Factor B, Factor D, Factor H, Factor I) were measured in TB patients with poor treatment outcomes (n=68) and disease-free controls (n=108).<h4>Results</h4>At both baseline (pre-treatment) and month two of anti-TB therapy, cases had significantly elevated levels of C3, C3b, C4b, C5, C5a, and C1q, and reduced levels of Factor B and Factor H compared to controls.