GLOMERULAR FC-ALPHA-R EXPRESSION AND DISEASE-ACTIVITY IN IGA NEPHROPATHY

In this study, we examined the receptors for the Fc portion of immunog lobulin A (IgA) (Fc alpha R) in the glomeruli as well as circulating p olymorphonuclear leukocytes and monocytes at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) assay and at the pro tein level by an immunohistochemistry/flow cytometry technique using a specific anti-Fc alpha R monoclonal antibody (My 43), Glomeruli were isolated from biopsy specimens of renal tissues from IgA nephropathy ( IgAN; 20 cases) and non-IgA mesangial proliferative glomerulonephritis (PGN; 13 cases) patients, and from normal renal tissue specimens obta ined from kidneys removed because of malignancies (five cases) applyin g the microdissection method, There was a relative increase in Fc alph a R in the circulating phagocytes from IgAN patients compared with tho se from PGN and healthy controls, Fc alpha R expression was present in approximately 40% of glomeruli samples from IgAN patients at the mess age levels, Fc alpha R-positive specimens were also strongly positive for expression of tumor necrosis factor-alpha, interleukin-1, and inte rleukin-6 mRNA, Specimens from PGN patients and healthy controls did n ot show any detectable Fc alpha R message, Serum IgA levels and severi ty of hematuria were significantly higher in patients with positive Fc alpha R expression, A message for Fc alpha R was detected in the tiss ues that were more damaged histologically, Our data suggest that there is some in vivo induction of glomerular Fc alpha R expression, possib ly mediated by a synergistic stimulus from IgA and inflammatory cytoki nes, and the expressed receptor is likely to be involved in the diseas e process of IgAN, (C) 1997 by the National Kidney Foundation, Inc.