Evaluation of immunoglobulin G and its subclasses in aplastic anemia

We selected 31 patients with aplastic anemia to measure their total immunoglobulin (Ig) G and IgG subclasses and compared the results obtained with those obtained in the normal control group (n=461). Patients with aplastic anemia were classified into three subgroups according to severity: mild subgroup (n=14), moderate subgroup (n=12) and severe subgroup (n=5). The decrease in total IgG was recognized in all these three subgroups (p<0.001). Although IgG1 decreased in severe subgroup (p<0.01), it showed no significant difference in mild and moderate subgroups. The decrease in IgG2 and IgG3 was observed in all these three subgroups (p<0.001 and p<0.01, respectively). Although IgG4 decreased in mild subgroup (p<0.05), it showed no significant difference in moderate and severe subgroups. We speculated that the measurement of IgG subclasses was useful in understanding the pathophysiology of humoral immunity in aplastic anemia.