Impaired lymphocyte transformation in minimal change nephropathy in remission.

A group of 37 patients with minimal change nephropathy (MCN) in remission for a mean period of 4.9 years (range 0.25-10) and on no current treatment were found to have a lymphocyte response to the mitogen Concanavalin A which was significantly lower than normal (P less than 0.001). This reduction in lymphocyte transformation was mainly due to the 24 patients who had received in addition to steroids a course of cyclophosphamide from 1 to 12 years (mean 6.7 years) previously (P less than 0.005 when compared t normal). Although the lymphocyte response of the remaining group of 13 patients who had not been treated with cyclophosphamide was not significantly lower than normal, there were three whose lymphocyte response to Concanavalin A was below the normal range. Our findings indicate that remission of MCN may be accompanied by a persistence of the abnormal lymphocyte function which is present during the nephrotic phase, and that cyclophosphamide may cause or add to this defect by a long-term effect on lymphocytes.