C5a concentration did not increase within 24 h of pneumococcal infection and was comparable between the two genotypes (Fig. 5c), suggesting that elevated IgA/IgM concentrations in BALF from SPC-HAxTCR-HA mice do not contribute to enhanced immune-complex-driven complement activation within 24 h of Streptococcus pneumoniae infection. This evidence concerns the gene CD40LG and pneumococcal infection.