Incidence of latent mesangial IgA deposition in renal allograft donors in Japan.
BACKGROUND
Mesangial immunoglobulin A (IgA) deposition is incidentally encountered in asymptomatic individuals, but its precise frequency and significance had not been clarified. The background of the latent IgA deposition is related to the epidemiology and pathogenesis of IgA nephropathy.


METHODS
Zero-hour allograft biopsies were performed in 510 renal transplantations (446 living donors, and 64 cadaveric donors) at the Kidney Center of Tokyo Women's Medical University. Mesangial IgA and C3 deposition were analyzed immunohistochemically, and the frequency and clinicopathologic features of mesangial IgA deposition were investigated.


RESULTS
Mesangial IgA deposition was present in 82 (16.1%) of the total 510 allografts with no statistical difference between living donors (72/446, 16.1%) and cadaveric donors (10/64, 15.6%) or between blood-related donors (66/392, 16.8%) and nonblood-related donors (16/110, 14.5%). Mesangial C3 deposition was present in 16 (19.5%) of the 82 allografts with mesangial IgA deposition. The grade of hematuria in IgA(+) donors was significantly higher than IgA(-) donors (1.30 +/- 1.17 vs. 0.86 +/- 0.89, P = 0.025). Histologic investigation of IgA(+) allografts revealed the frequency of mesangioproliferative glomerulonephritis (PGN) was significantly higher in IgA(+)/C3(+) allografts (8/16, 50%) than in IgA(+)/C3(-) allografts (11/66, 16.7%) (P = 0.0084). Moreover, the number of infiltrated macrophages to glomerulus (cells/glomerular cross section) was significantly higher in the IgA(+)/C3(+) allografts than in IgA(+)/C3(-), IgA(-)/C3(+) and IgA(-)/C3(-) allografts (1.10 +/- 0.62 vs. 0.61 +/- 0.42, P = 0.0008; 0.47 +/- 0.34, P = 0.023; and 0.37 +/- 0.23, P = 0.002, respectively).


CONCLUSIONS
The latent mesangial IgA deposition was a relatively common phenomenon in the healthy Japanese donors. This phenomenon was associated with mild degree of microhematuria, mesangial proliferation and glomerular macrophage infiltration in some of the affected individuals, especially with combined IgA and C3 deposition.
Suzuki
Koichi
K
Department of Medicine, Kidney Center, Tokyo, Japan.
Honda
Kazuho
K
Tanabe
Kazunari
K
Toma
Hiroshi
H
Nihei
Hiroshi
H
Yamaguchi
Yutaka
Y
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002102:Cadaver; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000378:metabolism; D005260:Female; D005922:Glomerulonephritis, IGA / Q000453:epidemiology* / Q000473:pathology / Q000652:urine; D006650:Histocompatibility Testing; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism*; D015994:Incidence; D007223:Infant; D007564:Japan / Q000453:epidemiology; D007678:Kidney Glomerulus / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016030:Kidney Transplantation / Q000706:statistics & numerical data*; D019520:Living Donors / Q000706:statistics & numerical data*; D008264:Macrophages / Q000473:pathology; D008297:Male; D008875:Middle Aged; D014184:Transplantation, Homologous
D003176:Complement C3; D007070:Immunoglobulin A