CD22 and infection: As we wanted to determine IRA B cells after E. coli infection with a protocol consistent with a previous report [13], we did intratracheal infections with E. coli. All CD22-/- mice and the C57BL/6 controls survived intratracheal infection for at least 72 hours post-infection with E. coli. 72 hours after intratracheal infection with E. coli CD22-/- mice had significantly lower levels of IRA B cells in the lungs (p<0.01) (Fig 8C).