Context: Little is known about pathogenesis of obesity-related liver disease in childhood. Data on relationship between leptin, immunological parameters and liver disease in obese children are lacking.

Object: Thus, the objective of this study was to evaluate immune phenotype and leptin serum levels in obese children with and without obesity-related liver disease.

Design: the study was performed in two groups of consecutive obese children: the first formed by children with obesity-related liver disease, diagnosed in presence of chronic hypertransaminasemia, liver steatosis at ultrasound and absence of known etiologies; the second was composed of children with isolated obesity. In all patients serum leptin, immunoglobulins, peripheral T, B and NK cells were evaluated.

Results: Twenty-three children in the first group and 16 children in the second were considered eligible. Serum leptin was increased in both groups but without any significant difference. No significant correlation was found between leptin and aminotransferases, lipids serum levels and all tested lymphocyte subpopulations. Patients with obesity-related liver disease showed significantly higher peripheral NK and B cells counts and IgA levels than children with isolated obesity. Furthermore, no correlation was found between severity of liver disease and lymphocyte subpopulations.

Conclusion: In our study leptin did not correlate with hepatic steatosis, aminotransferases and serum lipids. Children with obesity-related liver disease showed significantly higher peripheral NK and B cells and IgA levels. Further studies are required to define the pathogenetic role of these immunological findings.