A. BAFF and APRIL mRNA were detected in both peripheral CD4+ T cells (CD4-RNA; HD, n = 10; LTBL, n = 12; LTBH, n = 7; TB, n = 10) and CD4+ T cell-depleted PBMCs (N-CD4-RNA; HD, n = 6; LTBL, n = 12; LTBH, n = 7; TB, n = 6). The gene expression levels of BAFF and APRIL were normalized to β-actin. B. Soluble BAFF (sBAFF) and APRIL (sAPRIL) were measured by ELISA in plasma (HD, n = 22; LTBL, n = 12; LTBH, n = 14; TB, n = 11; TP, n = 11; CA, n = 14) and pleural effusion (TP, n = 10; CA, n = 14). C. Flow cytometry was employed to detect BAFF, BAFFR and TACI expression on the surface of peripheral CD4+ T cells from HD participants (n = 2) and TB patients (n = 2). D. M.tb antigen stimulation slightly augmented the frequency of BAFFR+CD4+ T cells in PBMCs from TB patients (TB-sti, n = 2) compared with un-stimulated cells (TB n-sti, n = 2). E. With or without M.tb antigen stimulation, the levels of sBAFF and sAPRIL were detected by ELISA in the supernatants of PBMCs from TB patients (n = 5). The stimulated supernatants of PBMCs from the HD group (n = 5) were used as a control. HD-sti: M.tb antigen-stimulated PBMCs from HD participants; TB-sti: M.tb antigen-stimulated PBMCs from TB patients; TB n-sti: un-stimulated PBMCs from TB patients.