LTA secretion by cHL cells drives NF-κB activation through a self-sustained feedback loop. (A) Flow scheme, identification of NF-κB–activating factors in L1236 cHL cell secretome. (B) HeLa cells were left untreated (UT) or were stimulated with SUP of L1236 cells for 24 hours with 80 µg/mL immunoglobulin G control (IgG) or LTA-neutralizing antibody (nAb). Subcellular localization of the indicated proteins was determined in cytoplasmic (C) and nuclear (N) extracts by western blot analysis and NF-κB activation by EMSA (bottom panel). (C) HeLa cells were treated with conditioned SUP of the cHL cell lines with 100 µg/mL human Fc control (Fc) or etanercept (Eta). Whole-cell extracts were analyzed for NF-κB DNA binding by EMSA. (D) Box plot representing the distribution of LTA mRNA expression in malignancies and normal B cells.¹⁴  cHL samples are indicated in red. (E) Chromatin immunoprecipitation was performed in L1236 cells using p52 and RelB-specific antibodies. Regulatory regions of LTA and TNFRSF14 were analyzed for DNA recruitment. Error bars represent the standard error of the mean. (F) Knockdown of the noncanonical NF-κB subunits was performed in L1236 cells. Cells were harvested after 4 days. Whole-cell extracts were analyzed by western blotting for expression of LTA, using LDH-A as control. (G) L1236 cells were transduced with either pWPI control or A20-expressing vector. Expression of A20, LTA, and LDH-A was determined by western blotting as in (F). BL, Burkitt’s lymphoma; CB, centroblasts; CC, centrocytes; DLBCL, diffuse large B-cell lymphoma; FL, follicular lymphoma; M, mature B cells; N, naive B cells; NLPHL, nodular lymphocyte-predominant Hodgkin lymphoma; NSC, non-silencing siRNA control; PC, plasma cells; TCRBL, T-cell–rich B-cell lymphoma.