Isotype switching is not disrupted in Stat3^fl/flCD19^Cre/+ mice. Stat3^fl/flCD19^Cre/+ (KO) mice (○) were able to elicit equivalent TD IgE responses (A) and TD IgA responses (B) compared with Stat3^fl/flCD19^+/+ (Wt) mice (•) in response to TD Ag. Mice were immunized with TNP-CGG as before, except that for induction of IgE, alum was used instead of CFA.