Production of C3 nephritic factor by cultured lymphocytes derived from glomerulonephritic patients

C3 nephritic factor (C3 NeF) has been found mainly in the sera of patients with membranoproliferative glomerulonephritis (MPGN) and partial lipodystrophy (PLD). We examined whether peripheral blood mononuclear cells (PBMC) from patients with PLD and MPGN could produce C3 NeF. We investigated the in vitro immunoglobulin synthesis of PBMC with mitogen. We further studied whether or not C3 NeF was included in the IgG of the culture supernatants by the C3bBb stabilizing activity and agglutination assay. The IgG of PLD patient was able to agglutinate only EAC4bBb cells and none of the other intermediate cells. We thus demonstrated that C3 NeF could be produced in vitro by PBMC derived from the patient with PLD. However, as regard case of C3 NeF weakly positive and C3 NeF negative patients, C3 NeF couldn't be produced in vitro by PBMC derived from the patients.