27 December 2005
Background/Aims: The therapeutic effect of cyclosporine A (CsA) in combination with steroids varies greatly for frequent-relapse minimal change nephrotic syndrome (FRMCNS). The association between the sensitivity of peripheral blood lymphocytes (PBLs) to CsA in vitro and the therapeutic effect of CsA in FRMCNS were investigated. Methods: The sensitivity of PBLs in vitro and the therapeutic effect of CsA in 23 FRMCNS patients were compared. The length of time to complete remission (CR) and the number of relapses were compared using the 50% inhibitory concentration (IC<sub>50</sub>) of CsA in the presence of a T-cell mitogen. Results: FRMCNS patients were divided into 2 groups: a low sensitivity group with an IC<sub>50</sub> of >14.8 ng/ml (GII, n = 10), and a high sensitivity group with an IC<sub>50</sub> of <14.8 ng/ml (GI, n = 13). Comparison of the length of time to CR between the 2 groups showed that GI reached CR earlier than GII (p < 0.01). GI had significantly fewer relapses than GII when CsA was administered for 12 months or longer (p < 0.01). Conclusion: Lymphocyte sensitivity to CsA has the potential to be an important clinical indicator of the antiproteinuric effect and relapse rate in FRMCNS.