In vivo analysis of the effect of B cell–enforced Bcl2 expression on tolerance induction with NP–PA–bNeuGc. Bcl2 Tg or nontransgenic littermates were challenged with NP–PA–bNeuGc on day 0, followed by rechallenge with NP–PA on day 17. Shown are IgM and IgG3 antibody titers of sera obtained at day 7 after primary or secondary challenge. Transgenic and nontransgenic littermates were immunized and sera were taken in three independent, noncontemporaneous immunization experiments; these sera were analyzed together by ELISA. Note that one Bcl2 Tg mouse had an extremely high titer that is given on a different scale than the other data points. No statistically significant differences were seen between Bcl2 Tg and nontransgenic littermate responses to NP–PA only (Fig. S5). ***, P < 0.005 using the two-tailed Student’s t test. n.s., not significant.