Figure 2.Atg5-deficient B cells have decreased Ig secretion, despite the ability to express Ig and undergo CSR. (A) Purified B cells were cultured on anti-Ig coated ELISpot plates and antibody-secreting cells (ASCs) were enumerated after 24 h. Numbers of IgM ASCs (top left), IgG ASCs (top middle) and IgA ASCs (top right) are shown relative to the number of ASCs present in each WT mouse tissue. *p < 0.001; n ≥ 10 per group. Representative ELISpot wells are shown for each tissue (bottom). BM, bone marrow; PerC, peritoneal cavity; MLN, mesenteric lymph node; PP, Peyer’s patches; LP, lamina propria. (B) Total IgM and IgG expression levels were quantified by flow cytometry. Representative histograms from MLN display WT (blue line) and CKO (red line) Ig distributions in CD19+ cells. Isotype control staining is shown in gray. (C) Purified naïve B cells were induced to undergo CSR to IgG1, IgG3 or IgA. Percentages of class-switched B cells were determined via flow cytometry after 4 d. No significant differences were observed via Student’s t-test.