Objective: Recent studies suggest that T cell dysfunction, especially IL-4, may be involved in the pathogenesis of steroid sensitive nephrotic syndrome (SSNS). The aim of this study was to investigate the association between the polymorphisms in variable numbers of tandem repeat region (VTR) of IL-4 gene and childhood SSNS.
Method: The polymorphism in the IL-4 gene was identified by using the polymerase chain reaction and direct sequencing methods in 55 Chinese children with SSNS, who were followed-up for at least 1 year, and 115 healthy Chinese adult blood donors as controls. A variable number of tandem repeat (VNTR) region polymorphisms of IL-4 gene were detected, and alleles were designated as IL-4 B1 and B2, corresponding to 2 and 3 repeats, respectively. The serum IgE was also examined in 48 patients before the steroid treatment.
Result: (1) There were no significant differences in the genotype and allele frequencies between patients with SSNS and normal controls (P > 0.05). (2) The frequencies of B1B1 (96.4%) were significantly higher in SSNS children with frequent relapses (28 patients had more than 3 relapses during the first year of the disease) than in 27 patients without frequent relapses (P < 0.05). (3) Twenty-three patients with frequent relapses showed higher levels of serum IgE (1.98 +/- 0.23 g/L) than 25 patients (IgE: 1.05 +/- 0.19 g/L) without frequent relapses (P < 0.05), and the patients with B1B1 (38 patients) also had higher serum IgE levels than patients with B1B2 and B2B2 (10 patients) (P < 0.05).
Conclusion: The results suggest that IL-4 VNTR B1B1 genotype might be a predictor for the frequent relapse in childhood SSNS in Chinese.