What is the significance of HLA-DR antigen expression in the extraglomerular mesangium in glomerulonephritis?
OBJECTIVE
The HLA-DR antigen is a HLA class II molecule involved in the presentation of antigenic peptides to the T cell receptor, thus regulating the immune response. Renal expression of the HLA-DR antigen may indicate specific sites of immunologically-mediated kidney injury in glomerulonephritis (GN). The aim of our study was to assess the presence of the HLA-DR antigen along the nephron including the extraglomerular mesangium in GN.


METHODS
A cross-sectional study of 22 patients with glomerulonephritis, mean age: 46.59±10.77 years, 14 male and 8 female, was conducted. Conventional stains, as well as immunohistochemistry for the HLA-DR Antigen Alpha-Chain were employed on kidney biopsies. Immunohistochemistry was assessed using a semi-quantitative score: 0-absent, 1-mild, 2-moderate, 3-intense. Statistical analysis was performed using SPSS17.


RESULTS
Four patients presented Focal and Segmental Glomerulosclerosis (FSGS), 5 patients: membranoproliferative GN, 7 patients: membranous nephropathy, 3 patients: mesangial proliferative GN, 2 patients: minimal change disease (MCD), and 1 patient: crescentic GN. Regarding the percentage of cases with HLA-DR positive cells along the nephron out of 22 patients: glomerular endothelial cells were 100% positive, intraglomerular mesangium cells were 81.8% positive, podocytes were 36.4% positive, extraglomerular mesangium cells were 31.8% positive, proximal tubule cells were 95.5% positive, distal tubule cells were 68.2% positive, interstitial capillaries were 77.3% positive, and cells of interstitial infiltrates were 27.3% positive. The percentage of cases staining positively for the HLA-DR antigen in the extraglomerular mesangium was 25% in FSGS, 60% in membranoproliferative GN, 0% in membranous nephropathy, 33.3% in mesangial proliferative GN, 100% in minimal change disease and 0% in crescentic GN.


CONCLUSIONS
A prominent HLA-DR antigen distribution was found on glomerular endothelial cells, intraglomerular mesangium cells and proximal and distal tubular cells. Extraglomerular mesangium cells and podocytes stained variably for the HLA-DR antigen, as did the cells of the interstitial infiltrates. The extraglomerular mesangium which serves as a portal of entry into the intraglomerular mesangium is endowed with antigen-presenting capabilities and is a region where induction of immune reactions could take place.
Division of Nephrology, University of Medicine and Pharmacy "V. Babes" Timisoara, Romania. gluhovschi@yahoo.com
Cristina
C
Gluhovschi
Gheorghe
G
Gluhovschi
Elena
E
Potencz
Elena
E
Lazar
Ligia
L
Petrica
Gheorghe
G
Bozdog
Florica
F
Gadalean
Flaviu
F
Bob
Daniel
D
Cioca
Silvia
S
Velciov
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005920:Glomerular Mesangium / Q000276:immunology* / Q000378:metabolism; D005921:Glomerulonephritis / Q000175:diagnosis / Q000276:immunology* / Q000378:metabolism; D006684:HLA-DR Antigens / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007678:Kidney Glomerulus / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D050527:Mesangial Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged
D006684:HLA-DR Antigens