IgM levels and infection risk. (A). Mean total IgM levels before and after starting rituximab infusions (♦), showing significantly lower levels at the 3-, 6-, 9-, and 12-month intervals when compared with those who did not receive rituximab () after autologous transplantation. NS indicates not significant; *, P < .02; **, P < .001; and ***, P < .0001. (B) The cumulative episodes of infections in the rituximab group (□) and the control group (▪), showing that there was an obvious excess of infective episodes in patients who received rituximab.