Beneficial effect of second courses of cytotoxic therapy in children with minimal change nephrotic syndrome

Dominant T cells in idiopathic nephrotic syndrome of childhood

BACKGROUND

Because of several studies, idiopathic nephrotic syndrome (INS) of childhood is suspected to have an immunologic pathogenesis with T cells playing a major role. To investigate this hypothesis further, we studied the diversity of the CDR3 region of the T-cell receptor (TCR) beta-chain from peripheral T cells isolated from patients with INS.

METHODS

The study was performed over a three-year period to obtain longitudinal data on the repertoire of peripheral T cells. mRNA from peripheral mononuclear cells (PBMCs) of seven INS patients and two healthy controls (NHD) was prepared and analyzed for CDR3 length polymorphism of TCR beta-chain by spectratyping.

RESULTS

All INS patients presented individually skewed spectratype histograms in at least one Vbeta-family. Patients suffering from a frequent relapsing course of INS or a focal global sclerosis showed some alterations to persist in all samples isolated in the observation period (up to 3 years). In addition, sequence analyses of the beta-chain of the TCR CDR3 region confirmed clonal expansion of peripheral T cells in those patients who had displayed spectratype alterations.

CONCLUSIONS

The data give strong evidence for an direct involvement of CD8+ T cells in the complicated course of INS.

Long-term cyclosporine A treatment of steroid-resistant and steroid-dependent nephrotic syndrome

Eighteen patients with steroid-resistant nephrotic syndrome (SRNS) and steroid-dependent nephrotic syndrome (SDNS) were treated with cyclosporine A (CyA) (6 mg/kg/d) for 2 to 29 months. CyA levels were monitored monthly and plasma levels by Abbott TDX (Therapeutic Drug Analyzer System) fluorescence polarization immunoassay were maintained at 100 to 150 ng/mL. The corticosteroid dosage administered at the time CyA therapy was initiated was variable and was continued following CyA therapy. Six of these patients (all with SDNS and minimal change nephrotic syndrome [MCNS]) had been treated with one or more courses of cytotoxic drug therapy, and all had clinical evidence of corticosteroid toxicity after receiving corticosteroid therapy for 26 to 120 months. The corticosteroid dosage was reduced by slow tapering and was ultimately discontinued in six patients. These patients were maintained on CyA monotherapy for 7 to 21 months at a dose of 3.2 to 6.7 mg/kg/d. Following 11 to 29 months of CyA therapy, seven patients underwent an elective renal biopsy, which showed nephrotoxicity in all seven. This led to discontinuation of CyA in four patients. Following discontinuation of CyA monotherapy, all four patients relapsed within 2 to 4 months. CyA therapy did not achieve a remission in 10 patients with SRNS regardless of the presence of focal segmental glomerulosclerosis (FSGS) or MCNS on renal biopsy. In conclusion, CyA has limited effectiveness in patients with SDNS who manifest corticosteroid toxicity; however, CyA should be used cautiously because of the potential for CyA nephrotoxicity and the failure to obtain a sustained remission following discontinuation of CyA monotherapy. CyA dependence is substituted for corticosteroid dependence.