Figure 5.Atg5-deficient B cells are defective in plasma cell differentiation. (A) The frequency of SDC1-expressing cells was determined via flow cytometry. Representative dot plots from MLN are shown and numbers represent the percentage of CD19⁺ B cells expressing SDC1. (B) The number of SDC1⁺ cells was quantified in mesenteric lymph nodes and spleen at baseline and after TNP-CGG immunization. *p < 0.01 comparing basal to TNP-CGG immunized. (C) ATG5 deletion was confirmed by western blot. MEFs harvested from WT and Atg5-deficient mice were used as controls in lanes 1 and 2. Sorted CD19⁺B220⁺SDC1⁻ and CD19⁺B220⁺SDC1⁺ populations from the mesenteric lymph nodes of WT and CKO mice were assessed. (D) CD19⁺B220⁺SDC1⁻ cells were sorted from the MLN of WT and CKO mice and cultured with LPS (10 μg/mL) or CpG (1 μg/mL) for 48 h on ELISpot membranes. Anti-IgM antibody-secreting cells were quantified and numbers shown are relative to the number of antibody-secreting cells in WT samples. *p < 0.001; n = 6 per group. (E) Prdm1, Xbp1 and Il6 mRNA expression in sorted CD19⁺B220⁺SDC1⁻ populations from the mesenteric lymph nodes of WT and CKO mice after 48 h of LPS stimulation. Numbers shown represent fold induction after LPS stimulation within each group. *p < 0.001 comparing fold induction in WT vs. CKO; ns = not significant; n = 6 per group.