Complete ablation of tumor necrosis factor decreases the production of IgA, IgG, and IgM in experimental central nervous system tuberculosis

This study aimed to explore the contribution of tumor necrosis factor (TNF) in the recruitment of B-cell and secretion of immunoglobulins (Igs) during cerebral tuberculosis (TB). In this work, the contributing role of TNF in regulating Ig secretions was investigated by comparing wild type TNF (TNFf/f), B-cell-derived TNF (BTNF-/-), and complete TNF ablation (TNF-/-) in a mouse cerebral Mycobacterium tuberculosis infection. Using flow cytometry and ELISA, we were able to examine the recruitment of B-cell subsets, and the production of Igs; also assessed the expression of surface markers on B cell subsets. Here, we found that TNF-/- mice showed defective expression of IgA, IgG, and IgM antibodies compared with TNFf/f and BTNF-/- mice, which was significantly decreased in the expression of surface markers and co-stimulatory molecules. Moreover, mice that produced low antibody levels were not able to control infection, therefore progressed to disease; providing direct evidence for the TNF gene-regulating humoral immunity during central nervous system (CNS) M. tuberculosis infection. In contrast, BTNF-/- mice controlled the infection and had levels of IgA, IgG, and IgM comparable to TNFf/f mice. Together, our results demonstrate that TNF may serve as an essential regulator of antibody-mediated immune responses in CNS TB. However, the protective level exhibited by TNF-producing B cells could be defined as baseline protection that could be used in the development of new therapeutic targets or designing new vaccines.