Allele-specific and peptide-dependent recognition of swine leukocyte antigen class I by human cytotoxic T-cell clones.
BACKGROUND
The T-cell mediated immune responses play a major role in xenograft rejection. However, the mechanisms behind human T-cell recognition of porcine xenoantigens remain to be elucidated.


METHODS
Human CD8+ T-cell lines were generated against porcine aortic endothelial cells (PAECs) from y/y and z/z haplotypes of Yucatan inbred swine. T-cell clones were obtained by limiting dilution. The human T-cell receptor (TCR)-swine leukocyte antigen (SLA) class I interaction was characterized.


RESULTS
The human CD8+ T-cell mediated direct recognition of PAECs was SLA haplotype-specific. The haplotype specificity was restricted by the SLA class I allelic polymorphism. To characterize the role of SLA-bound peptides in the human TCR-SLA class I interaction, we stripped peptides from SLA molecules by a brief acid treatment. Using z/z-specific CD8+ T cells as effectors, we demonstrated that the acid-treatment, which stripped SLA molecules of bound peptides, decreased the lysis of PAECs by 72%. Addition of peptides eluted from affinity purified z/z SLA class I molecules, but not from the irrelevant y/y SLA class I, restored the lysis of acid-treated z/z PAECs. In addition, the lysis of a human HLA class I negative cell line, 721.221, transfected with a relevant SLA class I allele derived from the z/z haplotype, was significantly increased with the addition of relevant z/z peptides. These experiments indicated that both SLA class I and bound peptides were required for recognition by human CD8+ T cells. Cloning studies identified two groups of xenoreactive T-cell clones. Group I clones recognized distinct porcine peptides in the context of SLA class I molecules, whereas group II clones recognized human endogenous cross-reactive peptides presented by SLA class I.


CONCLUSIONS
Our results demonstrated that, despite the differences in MHC molecules between species, human T-cell recognition of porcine MHC is similar to direct allo-recognition, that is, human TCR recognizes xenogeneic SLA-peptide complexes.
Xu
X C
XC
Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Naziruddin
B
B
Sasaki
H
H
Smith
D M
DM
Mohanakumar
T
T
D000483:Alleles; D000818:Animals; D015478:Antigens, Heterophile / Q000235:genetics; D002999:Clone Cells; D005805:Genes, MHC Class I; D006084:Graft Rejection; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D006801:Humans; D010455:Peptides / Q000276:immunology; D013552:Swine / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014162:Transfection; D014183:Transplantation, Heterologous
D015478:Antigens, Heterophile; D015395:Histocompatibility Antigens Class I; D010455:Peptides