Glomerular Fc alpha R expression and disease activity in IgA nephropathy

In this study, we examined the receptors for the Fc portion of immunoglobulin A (IgA) (Fc alpha R) in the glomeruli as well as circulating polymorphonuclear leukocytes and monocytes at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) assay and at the protein 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 obtained from kidneys removed because of malignancies (five cases) applying the microdissection method, There was a relative increase in Fc alpha R in the circulating phagocytes from IgAN patients compared with those from PGN and healthy controls, Fc alpha R expression was present in approximately 40% of glomeruli samples from IgAN patients at the message levels, Fc alpha R-positive specimens were also strongly positive for expression of tumor necrosis factor-alpha, interleukin-1, and interleukin-6 mRNA, Specimens from PGN patients and healthy controls did not show any detectable Fc alpha R message, Serum IgA levels and severity of hematuria were significantly higher in patients with positive Fc alpha R expression, A message for Fc alpha R was detected in the tissues that were more damaged histologically, Our data suggest that there is some in vivo induction of glomerular Fc alpha R expression, possibly mediated by a synergistic stimulus from IgA and inflammatory cytokines, and the expressed receptor is likely to be involved in the disease process of IgAN, (C) 1997 by the National Kidney Foundation, Inc.