Histological studies have demonstrated vascular damage in all types of allo
graft rejection. It is likely that donor endothelium suffers the major and
the first insult by the recipient's immune system since, in vivo, capillary
endothelium expresses human lymphocyte antigen (HLA) class I and class II
antigens. The present study was designed to examine whether injury to donor
endothelial cells (ECs) by recipient peripheral blood mononuclear cells (P
BMCs) can be demonstrated in vitro, and whether there is a relationship bet
ween the in vitro findings and the clinical outcome of renal allografts.
Twenty renal transplant recipients were included in this study, and all pat
ients were followed up for 6 months. PBMCs were isolated from the renal tra
nsplant recipients on three occasions; in the first 24-h posttransplantatio
n, at the beginning of the second week, and in the third week post-transpla
ntation. Additional samples were taken at the time of any acute rejection e
pisode. These patients received renal allografts from 15 local cadaveric do
nors whose ECs were isolated. Donor-specific ECs and the corresponding rena
l transplant recipients' PBMCs and sera were employed in proliferation and
cytotoxicity assays. Our results show that donor-specific ECs consistently
induced a highly significant degree of recipient lymphocyte proliferative r
esponse (p < 0.05). However, no significant correlation between acute graft
rejection and the degree of donor-specific EC-induced recipient lymphocyte
proliferation was found. In contrast, there was a significant correlation
between lymphocyte-induced EC cytolytic effects and acute renal graft rejec
tion (p < 0.05).
When conducted in larger studies, such information can have important impli
cations in clinical transplantation.