Defective TI-1 responses. Eight-week-old WT (□), Vav1^-/- (▦), Vav2^-/- (), and Vav1/2^-/- (▪) mice were injected intravenously with 20 μg (A) or 3 μg (B) DNP-LPS. Sera were collected at the times shown and analyzed by ELISA for DNP-specific antibodies of the isotypes indicated. ^*P < .05, ^**P < .005 by analysis of variance (ANOVA); n = 5. Bar graphs represent the mean of the optical density (OD) values for 5 mice per group, and error bars correspond to the standard error of the mean. (C) Purified B cells of WT and Vav-deficient mice (genotypes as described above) were cultured for 5 days in the presence of 20 μg/mL LPS, and secreted antibodies were analyzed by ELISA. Error bars indicate standard deviation of 6 wells; ^*P < .05, ^**P < .005 by ANOVA.