Low serum Levels of IgG-and IgM-rheumatoid factors in patients with idiopathic membanous nephropathy

• Published in: The Japanese Journal of Nephrology Vol. 27; no. 3; pp. 279 - 285
• Main Authors: MUSO, ERI, YOSHIDA, HARUYOSHI, SEKITA, KEN-ICHI, TAMURA, TADAO, KAWAI, CHUICHI, HAMASHIMA, YOSHIHIRO
• Format: Journal Article
• Language: English
• Published: Japanese Society of Nephrology 1985
• Subjects: Idiopathic membranous nephropathy; Immune complexes; Rheumatoid factors
• ISSN: 0385-2385; 1884-0728
• DOI: 10.14842/jpnjnephrol1959.27.279

IgM and IgG rheumatoid factors (RF) were measured by radioimmunoassay in 25 serum and 10 urine samples of patients with idiopathic membranous nephropathy (MN), 29 sera of systemic lupus erythematosus (SLE), 29 of rheumatoid arthritis (RA) and 29 of normal controls. Significantly low levels of IgM-RF and IgG-RF were detected in the sera of MN patients (P<0.02, P<0.05), whereas the IgM-RF levels were significantly high in the sera of RA patients. The 17 MN patients with nephrotic syndrome showed significantly low levels of serum IgG-RF (P<0.05) and IgM-RF (P<0.01), in comparison with 10 nephrotic controls (minimal change, 6; diabetic nephropathy, 4), There was no evidence that serum RF of nephrotic patients with MN flowed out in the urine. A good correlation was obtained between IgG- and IgM-RF in the sera of MN patients. The immune complexes (IC) of IgG class, detected in MN patients' sera by solid phase Clq (ClgSP) binding assay and solid phase conglutinin (KgSP) binding assay, were compared with the levels of serum IgG-RF. No patients sera showed higher than the normal range of IC levels by ClgSP assay, and only 5 of 25 sera (20%) revealed higher levels by KgSP assay. The levels of IgG-RF showed an excellent correlation with the amounts of SPClq-IC (P<0.001), and a relatively good correlation with those of SPKg-IC (P<0, 02). These data may support the immunopathological background of MN, i.e. suppressed production or accelerated clearance of antibodies including RF.