CD40LG and pertussis: Conversely, serum IgM (0.72 ± 0.5 g/L versus 0.98 ± 0.8 g/L, p = 0.04), albumin (38.7 ± 4.7 g/L versus 48.4 ± 5.2 g/L, p < 0.01), and globulin levels (14.8 ± 5.7 g/L versus 19.7 ± 5.1 g/L, p = 0.03) were significantly lower in the pertussis group.