TI responses are unperturbed in Stat3^fl/fl CD19^Cre/+ mice. Stat3^fl/flCD19^+/+ (Wt) and Stat3^fl/flCD19^Cre/+ (KO) mice were immunized with TNP-Ficoll in PBS, and TNP-specific antibody responses were measured on the days indicated. TI TNP-specific IgM (A) or IgG3 (B) levels were equivalent between Wt (•) and KO (○) mice.