Intracellular cytokines of peripheral blood lymphocytes in nephrotic syndrome

Idiopathic nephrotic syndrome (NS) is probably caused by abnormalities in T-lymphocyte function. The presence of several immunological abnormalities in these patients supports this hypothesis, but to date there is no agreement about immunological status and its influence on the course of NS. Thirty-six children with NS [19 with first episode (group I) and 17 in remission (>6 months) of NS (group II), aged 4–17 years, mean 7.1 years] were included in the study. Nineteen age-matched healthy children constituted the control group. Anti-cytokine antibodies were used in conjunction with antibodies against cell surface antigens to study cytokine synthesis in different lymphocyte populations. In the present study the intracellular synthesis of interleukin-2 (IL-2), interferon-γ (IFN-γ), IL-4, and IL-6 was measured. The intracellular synthesis of IL-2 was higher in group I compared with the controls, both in the whole population of T-lymphocytes (12.1±6.2% vs. 7.6±6.7%, P=0.0281) and in the subpopulation of CD8– lymphocytes (17.3±8.5% vs. 7.2±4.8%, P=0.0001). No significant differences in IFN-γ intracellular expression were found. The intracellular synthesis of IL-4 was lower in group I compared with the controls, both in the whole population of T-lymphocytes (1.98±1.92% vs. 3.6±3.3%, P=0.012) and in the subpopulation of CD8– lymphocytes (2.4±2.3% vs. 6.5±6.4%, P=0.0002). Similarly, the intracellular expression of IL-6 was lower in group I compared with the control group, in the whole population of T-lymphocytes (0.85±0.6% vs. 2.2±3.1%, P=0.004), in the CD8– subpopulation (1.1±1.1% vs. 2.2±2.0%, P=0.006), and in the CD8+ subpopulation (1.1±0.9% vs. 2.8±3.4%, P=0.0008). The results of this study indicate that the acute episode of NS is associated with increased intracellular synthesis of IL-2 and decreased intracellular synthesis of IL-4 and IL-6.