Enhanced Mycobacterial Antigen-Induced Pro-Inflammatory Cytokine Production in Lymph Node Tuberculosis

Abstract

Lymph node tuberculosis (LNTB) is characterized by the enhanced baseline and antigen-specific production of type 1/17 cytokines and reduced baseline and antigen-specific production of interleukin (IL)-1β and IL-18 at the site of infection when compared with peripheral blood. However, the cytokine profile in the lymph nodes (LNs) of Mycobacterium tuberculosis culture-positive LNTB (LNTB+) and negative LNTB (LNTB-) has not been examined. To address this, we have examined the baseline and mycobacterial antigen-stimulated cytokine levels of type 1 (interferon gamma [IFNγ], tumor necrosis factor alpha [TNFα], IL-2), type 2 (IL-4, IL-5, and IL-13), type 17 (IL-17A, IL-17F, and IL-22), pro-inflammatory (IL-1α, IL-1β, IL-18, and granulocyte macrophage colony-stimulating factor [GM-CSF]), and regulatory cytokines (IL-10, transforming growth factor beta [TGF-β]) cytokines in the LN culture supernatants of LNTB+ and LNTB- individuals. We have observed significantly enhanced baseline levels of IL-13 and IL-10 and significantly reduced baseline levels of IL-4 and GM-CSF in LNTB+ individuals compared with LNTB- individuals. By contrast, we have observed significantly enhanced levels of type 1 (IFNγ, TNFα, and IL-2), type 17 (IL-17F and IL-22), and pro-inflammatory (IL-1α and GM-CSF) cytokines and significantly reduced levels of TGFβ in response to purified protein derivative, early secreted antigen-6, and culture filtrate protein-10 antigens in LNTB+ compared with LNTB- individuals. On phorbol 12-myristate 13-acetate/ionomycin stimulation, no significant difference was observed for any of the cytokines examined. Thus, our study revealed several interesting differences in the cytokine profiles of mycobacterial antigen-stimulated LN cultures in LNTB+ and LNTB- individuals. Therefore, we suggest the presence of mycobacteria plays a significant role in driving the cytokine response at the site of infection in LNTB.

Figure 1.

Baseline, purified protein derivative (PPD), and Phorbol 12-myristate 13-acetate/ionomycin (P/I) stimulated cytokine production in positive lymph node tuberculosis (LNTB+) and negative lymph node tuberculosis (LNTB−) individuals. The (A) unstimulated, (B) PPD and, (C) P/I stimulated culture supernatant levels of type 1 (interferon gamma [IFNγ], tumor necrosis factor alpha [TNFα], and interleukin [IL]-2), type 17 (IL-17, IL-17F, and IL-22), type 2 (IL-4, IL-5, and IL-13), regulatory (IL-10 and TGFβ), IL-1 family (IL-1α and IL-1β), and other pro-inflammatory (IL-18 and GM-CSF) cytokines were measured in lymph node cell suspensions of LNTB+ and LNTB− individuals. Each circle represents a single individual, and the bars represent the geometric mean values. Net cytokine levels were calculated by subtracting the baseline levels from the antigen-induced levels for each individual. P values were calculated using the Mann–Whitney U test.