Monocytes and peritubular capillary C4d deposition in acute renal allograft rejection.
BACKGROUND
Peritubular capillary (PTC) deposition of complement split factor C4d in renal allografts has been shown to be closely associated with circulating antidonor antibodies and a marker for relatively poor graft survival. Monocyte/macrophage (MO) infiltration of renal allografts has been shown to adversely affect graft survival. The purpose of this study was to assess whether the two phenomena are related.


METHODS
Twenty-three biopsies (from 15 patients) demonstrated diffuse strong staining of PTC for C4d (C4d+ group) and acute tubular injury with or without significant cellular rejection, while 28 biopsies (with acute rejection) but negative for PTC C4d served as controls (C4d- group).


RESULTS
The C4d+ group demonstrated significantly greater glomerular and interstitial MO infiltration than did the C4d- group [3.4 +/- 2.0 vs. 0.2 +/- 0.3 MO/glomerulus, P < 0.0001; 12.9 +/- 9.2 vs. 6.5 +/- 5.0 MO/high power field (hpf), P = 0.0030]. Neutrophilic (PMN) infiltration of glomeruli and PTC was also significantly greater in the C4d+ group than in the C4d- one (0.8 +/- 0.6 vs. 0.3 +/- 0.3 PMN/glomerulus, P = 0.0003; 0.9 +/- 0.8 vs. 0.4 +/- 0.3 PTC PMN/hpf, P = 0.0035).


CONCLUSIONS
The results indicate a close association between PTC C4d deposition and MO infiltration, particularly glomerular, and confirm previous observations regarding the correlation of PTC C4d staining and PMN infiltration.
Magil
Alex B
AB
Department of Pathology, St. Paul's Hospital and the Unversity of British Columbia, Vancouver, BC, Canada. amagil@providencehealth.bc.ca
Tinckam
Kathryn
K
D000208:Acute Disease; D000328:Adult; D001706:Biopsy; D002196:Capillaries / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D003181:Complement C4 / Q000378:metabolism*; D015935:Complement C4b; D005260:Female; D005921:Glomerulonephritis / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006084:Graft Rejection / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D016030:Kidney Transplantation; D007684:Kidney Tubules / Q000098:blood supply / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000473:pathology*; D010446:Peptide Fragments / Q000378:metabolism*
D003181:Complement C4; D010446:Peptide Fragments; D015935:Complement C4b; C032261:complement C4d