The increase in pulmonary edema was paralleled by an increase in lung permeability as measured by an increase of the high molecular weight protein IgM in BALF of PVM-infected mice, which reached significance on day 7 and 8 after infection (day 0: 84.3±6.2 vs day 7: 1092.0±266.6, p<0.01 and vs day 8: 1248.0±266.7, p<0.001) (Fig. 1C). Here, CD40LG is linked to infection.