Influence of iron deficiency on serum IgG subclass and pneumococcal polysaccharides specific IgG subclass antibodies.

The serum IgG subclass concentrations in 47 cases and specific IgG subclass antibodies against pneumococcal polysaccharides (PnPs) were measured in 18 cases with iron deficiency. IgG subclass deficiencies were found in 28 (59.6%) cases with the frequency in order as IgG4 (27.7%, 13/47), IgG1 (21.3%, 10/47), IgG3 (14.9%, 7/47), and IgG2 (2.1%, 1/47). Compared with age-matched healthy children, the mean concentration of serum IgG4 and IgG1, and PnPs specific IgG1, IgG2 antibodies were decreased in children with iron deficiency. Decreased CD4+ cells and CD4+/CD8+ ratio in peripheral blood, low interleukin-6 (IL-6) activity, reduced lymphocyte proliferative responsiveness and increased recurrent respiratory tract infections (RRTI) were found in iron deficiency children. These results suggested that serum IgG subclass and PnPs specific IgG subclass antibody deficiencies caused by dysfunction of the regulation of T lymphocyte on B lymphocyte may be related to the susceptibility to RRTI in children with iron deficiency.