IGHG3 and infection: The levels of IgG1 and IgG3 were significantly higher than the level of IgG2 and IgG4 during acute phase of infection (IgG1 versus IgG2, P = 0.004; IgG1 versus IgG4, P = 0.022; IgG2 versus IgG3, P = 0.004; IgG3 versus IgG4, P = 0.035).