Defective T cell–dependent antibody response in Dicer1^fl/flAicda^Cre/+ mice. (A-B) Serum anti–NP IgM (1:1000 dilution), IgG1 (1:9000 dilution), IgG2b (1:3000 dilution), and IgG3 (1:1000 dilution) antibodies from NP₃₈-CGG immunized Dicer1^+/+Aicda^Cre/+ (●) and Dicer1^fl/flAicda^Cre/+ (○) mice were measured by ELISA using NP₁₇-BSA (A) or NP₂-BSA (B) as coating antigens. Mice were immunized on day 0, and sera were collected at the indicated time points after immunization. (C) Ratios of anti-NP IgG1 and IgG2b titers detected with NP₂-BSA compared with NP₁₇-BSA as coating antigens in ELISA. Each symbol represents 1 mouse. Data shown are representative of 3 repeated experiments and each experimental group contained at least 5 mice. ***P < .001 (Student t test).