Detection of urinary macrophages expressing the CD16 (FcγRIII) molecule: A novel marker of acute inflammatory glomerular injury

Detection of urinary macrophages expressing the CD16 (FcγRIII) molecule: A novel marker of acute inflammatory glomerular injury.BackgroundThe CD16 antigen is the Fcγ receptor III. CD14+CD16+ cells are proinflammatory monocytes/macrophages (Mo/MΦ) that constitute a minor population in the peripheral blood of healthy individuals. Little is known about the expression of CD16 antigen on Mo/MΦ in glomerulonephritis.MethodsFlow cytometric analyses were performed on urine and blood samples obtained from 209 patients with various renal diseases. Patients variously suffered from rapidly progressive crescentic glomerulonephritis (RPGN), membranoproliferative glomerulonephritis (MPGN), postinfectious acute glomerulonephritis (AGN), Henoch-Schönlein purpura nephritis (HSPN), IgA nephropathy (IgAN), membranous nephropathy (MN), minimal change nephrotic syndrome (MCNS), lupus nephritis (LN), acute interstitial nephritis, hereditary nephropathy, idiopathic renal hematuria (IRH), and renal stone.ResultsThe CD16+ MΦ population of cells was present in the urine of hematuria-positive patients with proliferative glomerulonephritis, including AGN, IgAN, RPGN, MPGN, and LN with acute inflammatory lesions, such as endocapillary proliferation, tuft necrosis, and cellular crescents. In contrast, the urinary CD16+ MΦ population was negligible in hematuria-positive patients with nonproliferative renal disease, including hereditary nephropathy, IRH, and renal stone and also in patients with proliferative glomerulonephritis lacking acute inflammatory lesions. Total urinary MΦ of these patients were much less than those of patients having proliferative glomerulonephritis with acute inflammatory lesions. Transient expansion of the CD16+ MΦ population in urine was observed during the acute exacerbation of urinary abnormalities, whereas the disappearance of CD16+ MΦ closely preceded the amelioration of urinary abnormalities in patients with proliferative glomerulonephritis. In 38 of the 98 patients positive for CD16+ MΦ population in urine, the CD16+ Mo population was negligible in peripheral blood. Immunohistochemically, CD16+ MΦ were present in the glomeruli of active proliferative glomerulonephritis, whereas such cells were absent in inactive proliferative glomerulonephritis or nonproliferative glomerular diseases.ConclusionCD16+ MΦ may be effector cells involved in the acute inflammation common to all types of proliferative glomerulonephritis. Furthermore, the detection of CD16+ MΦ in urine, as well as urinary MΦ counts, may serve as a useful indicator of the active stage of proliferative glomerulonephritis