Mesenteric lymph nodes are required for B- but dispensable for local T cell effector responses following

Introduction: The intestinal immune system is organized into regionally specialized lymphatic drainage networks that coordinate adaptive responses according to the anatomical site of microbial encounter. During Methods: To examine the contribution of the colon‑draining mLN, we surgically removed either the entire mLN chain or only the nodes draining the cecum and colon, followed by Results: We found that Th17 effector responses in the colon were maintained independently of the removed mLN, consistent with the fact that local colonic activation is the primary driver of the observed T cell phenotype at these time points. In contrast, B cell differentiation was markedly impaired in mLN‑resected animals: both plasma cell frequencies in the colon and pathogen‑specific serum IgG1 and IgG2a responses were significantly reduced. Discussion: These findings indicate that, although distal‑colonic T cell activation proceeds locally, effective B cell activation and class switching depend on the presence of the appropriate draining lymph nodes. Overall, this study highlights the segment‑specific organization of intestinal immunity and demonstrates that B cell responses during