Tumor Necrosis Factor α from Peripheral Blood Mononuclear Cells of IgA Nephropathy and Mesangial Cell Proliferation

BACKGROUND To investigate the role of mononuclear cells and their products on rat mesangial cell proliferation, we evaluated the effect of peripheral blood mononuclear cells (PBMC) culture supernatant of patients with IgA nephropathy on rat mesangial cells 3[H]-thymidine uptake, and measured the concentration of cytokines in the supernatant to find out which cytokine in PBMC culture supernatant has a major influence on mesangial cell 3[H]-thymidine uptake. METHODS In ten patients with primary IgA nephropathy and 10 normal controls, PBMC were cultured with PHA (20 micrograms/ml) and con-A (10 micrograms/ml) for 24 hours, and supernatants were collected and stored at -70 degrees C until tested. Mesangial cell was cultured for 48 hours at a concentration of 10(4) cells/well with 1:2 or 1:10 diluted PBMC culture supernatant. 3[H]-thymidine uptake into rat mesangial cell was assayed after 18 hour culture. The cytokine concentrations of PBMC culture supernatant were measured by radioimmunoassay. RESULTS When 1:2 diluted PBMC culture supernatant was added, the supernatant of IgA nephropathy induced higher 3[H]-thymidine uptake into mesangial cell compared with that of normal controls. 3[H]-thymidine uptake induced by 1:2 diluted PBMC culture supernatant was significantly higher than that induced by 1:10 diluted supernatant of IgA nephropathy. The concentration of TNF-alpha in PBMC culture supernatant of the patients with IgA nephropathy was higher than that of normal controls and showed a good correlation with the mesangial cell 3[H]-thymidine uptake. CONCLUSION It is suggested that the mononuclear cell of IgA nephropathy may have the intrinsic property to produce more TNF-alpha which may be mitogenic to mesangial cells when stimulated with mitogens, and it may be related to the mesangial cell proliferation in IgA nephropathy.