Increased production of interleukin 4 in children with simple idiopathic nephrotic syndrome.

Sera and peripheral blood mononuclear cells (PBMC) were collected from 42 children with simple idiopathic nephrotic syndrome (INS) aged from 1.5 to 14 years and 28 age and sex-matched healthy children. The levels of IgE in serum and interleukin 4 (IL-4) in supernatant of PHA-activated PBMC were tested by ELISA. A significantly high incidence of allergic diseases was noted in INS children and their first-degree relatives, and there was a close association between atopy and INS. Besides, the levels of IgE and IL-4 were increased in nephrotic state (P < 0.001 both). IgE normal and IL-4 slightly lower in remission state (P < 0.2, P < 0.01 respectively). A positive correlation was noticed between IL-4 and IgE, and between IL-4 and 24-hour proteinuria (r = 0.472, r = 0.562; P < 005, P < 0.01 respectively). These showed a close association between atopy and INS. Both IL-4 and IgE, the important mediators in atopy, showed abnormal change in patients. The increased IL-4 production of T cells might account for the elevated serum IgE level. IL-4 may have a pathogenetic role in INS, but it still remains speculative.