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To determine whether patients with systemic lupus erythematosus (SLE) and active nephritis have more profound defects in suppressor cell activity, we studied concanavalin A (Con A)-induced suppressor cell activity (SCA) in 12 patients with lupus nephritis (LN) and 11 patients with chronic mesangial proliferative glomerulonephritis (CGN) without renal insufficiency. The levels of Con A-induced SCA were decreased in patients with LN compared with those in normal controls and those in CGN patients and lower in LN patients with the nephrotic syndrome (NS) than in those without NS. In contrast, the mean responses of Con A-induced SCA in CGN patients with or without NS did not differ from normal subjects. These findings may lend further insight into the understanding of the immunoregulatory defect in LN.

The T-colony-forming capacity was examined in 13 normal subjects and 8 patients with biopsy-proven focal glomerular sclerosis (FGS). Fifteen patients with chronic mesangial proliferative glomerulone-phritis (CGN) without renal insufficiency were studied as a disease control. The two main assays used were the counting of T colonies formed by the patients’ lymphocytes, and the measurement of T-colony-forming activity in conditioned medium from cultures of patients’ lymphocytes. The levels of T-colony-forming cells (TCFC) and T-colony-stimulating factor (TCSF) were decreased in patients with FGS compared with those in normal controls and lower in FGS patients with the nephrotic syndrome (NS) than in those without NS. In contrast, these parameters in CGN patients with or without NS did not differ from normal subjects. TCSF activity for TCFC in both normal individuals and FGS patients was removed from media conditioned by phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PHA-LCM) with interleukin-2 (IL-2) receptor bearing cultured T cells. These in vitro findings suggest that IL-2 is the essential factor contained in PHA-LCM. Thus, depressed TCFC in FGS ptients with NS may result in part from impaired generation of TCSF by lymphocytes.

Cell-mediated immunity (CMI) was studied in 28 patients with biopsy-proven lipoid nephrosis (LN). The LN patients with nephrotic syndrome (NS) had a significant depression in CMI, characterized by impaired delayed hypersensitivity skin reactivity to purified protein derivative (PPD), depressed local graft-versus-host reaction (GVHR), decreased proportion of T lymphocytes and diminished lymphocyte transformation to phytohemagglutinin (PHA). Concanavalin A (Con A)-induced suppressor cell activity (SCA) was found to be significantly increased in LN patients with NS compared to that in normal individuals. In contrast, the mean levels of CMI and SCA studied in LN patients in remission and in patients with chronic mesangial proliferative glomerulonephritis (CGN) did not differ from normal subjects. Our findings support the notion that at least in some LN patients with the NS, activated suppressor cells are present and possibly account for their decreased CMI.