(A) Anti-phosphocholine (PC) IgM is measured by ELISA for Btkflox (black, n-7), Btkflox/Cre-ERT2 five days after treatment (red, solid line, n=4), Btkflox/Cre-ERT2 five weeks after treatment (red, dashed line, n=3) and Btknull (blue, n=4). Statistics were performed using a 2-way ANOVA and listed in Supplemental Table 1.