Figure 3. IgA is dominant in activated B cells of intrinsic chimera mice.

(A) Breeding setup for WT IgH^a/b and Iga^+/− IgH^a/b mice.

(B, C) Percentage of IgA⁺ (B) and IgM⁺ (C) GC B cells in PPs. Solid bars represent indicated total isotype in GC; stacked bars represent allotypic isotype in GC of WT and Iga^+/− mice.

(D) Percentage of endogenously coated small intestinal bacteria with indicated antibodies.

(E, F) Percentage of intestinal commensal from μMT mice stained by IgA^a (E) or IgA^b (F) antibodies from Iga^+/+ or Iga^+/− serum.

(G, H) Percentage of intestinal commensal bacteria from μMT mice stained by IgM^a (G) or IgM^b (H) antibodies from Iga^+/+ or Iga^+/− serum. Dashed line represents unstained μMT bacteria in E-H.

(I) Experimental setup for cholera toxin(CT) oral immunization and subsequent MemB cell in vitro culture with NB21 feeder cells.

(J, K, L) ELISA OD for CT specific IgA (J), IgM^a (K), and IgM^b (L) antibodies detected in MemB supernatant 3.5 days after in vitro culture.

Data from at least 3 independent experiments with 2-3 mice per group (B-H). Data from 4 independent experiments with 1-3 mice per group (J-L). ns=not significant, *p < 0.005; **p < 0.001; ***p < 0.0005; ****p < 0.0001; Unpaired two-tailed Student’s t-test in B-H. One way ANOVA in J-L.

See also Figure S2.