Identification and quantitation of cells that process immune complexes in nephritic rats induced with bovine serum albumin.

A light microscopic autoradiography was used to determine which cell types positively disposed of the daily circulating immune complexes produced in rats with experimental immune complex glomerulonephritis. Our results indicated that polymorphonuclear leucocytes (PMNs) remove large quantities of immune complexes in the livers, spleens, and lungs of these rats. Semiquantitative autoradiography indicated further that the function of mononuclear phagocyte system decreased late in the course of glomerulonephritis; whereas, in compensation, the role of PMNs appeared to increase. Our data uncovered a significant role for PMNs in the disposition of immune complexes during the induction of experimental immune complex nephritis.

Desmin-positive epithelial cells outgrowing from rat encapsulated glomeruli.

Decapsulated glomeruli, encapsulated glomeruli and tubular fragments were each selected and cultured in order to identify the origin of polygonal epithelial cells in glomerular outgrowths and to characterize them by double-label immunofluorescence microscopy using antibodies against cytoskeletal proteins. Polygonal cells outgrew from less than 1% of decapsulated glomeruli, 34.8 to 65.1% of encapsulated glomeruli and 62.4 to 79.7% of tubular fragments in culture. These data support the idea that polygonal cells in glomerular culture are derived mainly from parietal epithelial cells of Bowman's capsule but not visceral cells, and indicate that polygonal cells of tubular epithelial origin are also present. Polygonal cells from encapsulated glomeruli consisted of intensely vimentin-positive (IV) cells and weakly vimentin-positive (WV) ones. Most of the IV cells showed various degrees of staining with anti-desmin antibody, and some of them also expressed cytokeratins and alpha-smooth muscle actin. By contrast, all of the WV cells were stained with anti-cytokeratin antibody but not with anti-desmin antibody. Polygonal cells in cultures of tubular fragments were negative for desmin. These findings suggest that parietal cells express desmin in culture, even though they show no desmin staining in kidney sections.

Visceral epithelial cells in rat glomerular cell culture.

The purpose of this study was to identify and characterize visceral epithelial cells (VECs) of renal glomeruli in culture. Such cells have been described variably as regular, polygonal cells showing a high rate of replication and a cobblestone-like appearance at confluence and also as irregular, arborized and often multinucleated cells showing a very limited proliferative capacity. We examined early outgrowths from the glomeruli by immunofluorescence microscopy using antibodies specific for VECs (anti-podocalyxin(1A), anti-pp44 and 5-1-6), for endothelial cells (anti-von Willebrand factor (vWF) and RECA-1) and for mesangial cells (anti-Thy-1). 1A and anti-pp44 reacted with several types of irregular, arborized cells, but never with regular, polygonal cells. 5-1-6 did not react with any of the cells. Neither the 1A- nor anti-pp44-positive cells (1A/pp44(+) cells) stained with anti-vWF, RECA-1 or anti-Thy-1. However, all the 1A/pp44(+) cells expressed desmin and vimentin but not cytokeratin. These results show that the 1A/pp44(+) cells are derived from VECs, supporting the idea that most polygonal cells in glomerular cultures are of parietal epithelial origin.

Attachment of polymorphonuclear leukocytes to glomeruli with immune deposits.

A method for quantitative evaluation of a biological activity of immune complexes deposited in glomeruli is described. The activity reflects the activation of complement and is represented by the number of PMN attached to a glomerulus. It is possible to compare data from different individuals or different phases of glomerulonephritis. The complement component concerned is considered to be C3, activated through the classical or alternate pathway.

Podocyte detachment and epithelial cell reaction in focal segmental glomerulosclerosis with cellular variants.

In primary focal segmental glomerulosclerosis with cellular variants the type of epithelial cells that segmentally or globally increased and their relation to sites where podocytes detached from the capillary wall, remain unclear. Two renal samples containing glomeruli with cellular variants were serially examined using transmission electron microscopy. A total of 10 lesions, including 2 collapsing glomerulopathy, 7 cellular lesions, and 1 sclerosis, were examined. Disappearance of the dense basal band of microfilaments from portions of podocytes was followed by detachment from the capillary basement membrane, resulting in segmental denudation of the capillary wall. The defects were not covered by other portions of epithelial cells, when the defects occurred in more central regions of the glomerulus. When detachment of podocytes occurred in the peripheral areas of the glomerulus, the defects were covered with new basement membrane and by other epithelial cells. These epithelial cells were characterized by the formation of intercellular junctional complexes of zonula adherens and desmosomes between each other and with the parietal epithelial cells (PECs), by showing occasional cilia, apoptotic nuclei, and mitosis. Thus, repair is achieved as the defect is covered by the participation of PECs; synechia and glomerular sclerosis result, depending upon the extent of the original podocyte injury.

[Histological study in renal grafts--macrophages population in renal grafts].

We studied about the histological findings of the kidneys including of the infiltrated macrophages in one hour post-transplantation kidney biopsies (one hour biopsies) and re-biopsies on 11 patients. They were transplanted at 4-28 (ave. 15.1 +/- 3.8) years of age. The periods from transplantation to this study were 1.0-7.3 (ave. 3.3 +/- 1.9) years. 6 patients had acute rejections, and their renal function became normal after treatments. At this study, all grafts survived, and the patients had no abnormal findings except two (one had proteinuria, another had proteinuria and mild elevation of serum creatinine level). But histologically, five patients had chronic rejections among the 8 patients who had re-biopsies more than one year after transplantation. And we experienced 6 patients whose kidney had mesangial IgA deposits in one hour biopsies and 3 patients who had de novo type glomerulonephritis in re-biopsies (IgA neuropathy in 2 patients, membranous nephropathy in one). In one hour biopsies, the populations of macrophages in the interstitium were 4.18 +/- 2.84/mm2 in the patients who would have acute rejections (6 patients), 1.38 +/- 1.13/mm2 in the cases who would not have. It was suspected that the increase of the infiltrated macrophages in the interstitium in one hour biopsies could predict acute rejections. In re-biopsies, many macrophages infiltrated in the interstitium (8.34 +/- 4.86/mm2), particularly on patients who had chronic rejections.

Urinary podocytes in primary focal segmental glomerulosclerosis.

BACKGROUND/AIM: Focal segmental glomerulosclerosis (FSGS) is a common cause of nephrotic syndrome. Although the pathogenesis is not known, recent studies suggest that FSGS may be a podocyte disease. The aim of this study was to look for podocyte injury in this disease, using measurements of urinary podocytes. METHODS: We examined the first morning urine of the day collected from 71 patients (45 men and 26 women, median age and range 11.2 and 3-29 years) diagnosed as having nephrotic syndrome. Freshly voided urine samples were examined by immunofluorescence labeling using monoclonal antibodies against human podocalyxin. Renal histological examinations were performed in 58 of the 71 patients: 28 had minimal-change disease, 20 had FSGS, and 10 had membranous nephropathy. RESULTS: Median and range of urinary podocytes measured were 0.2 and 0-40.8 cells/ml for 71 patients with nephrotic syndrome and 0 and 0-0.8 cells/ml for normal healthy control subjects (n = 200). Patients with FSGS had significantly higher levels of urinary podocytes (median and range 1.3 and 0-40.8 cells/ml) than those with minimal-change disease (median and range 0 and 0-6.9 cells/m; p = 0.003) or membranous nephropathy (median and range 0 and 0-1.4 cells/ml; p = 0.02). CONCLUSIONS: The urinary excretion of podocytes is significantly higher in patients with FSGS as compared with those having membranous nephropathy or minimal-change disease. These findings suggest that podocyte injury and loss in the urine may have an important role in the pathogenesis of FSGS.