HLA-Cw4 expression on porcine endothelial cells reduces cytotoxicity and adhesion mediated by CD158a+ human NK cells.
BACKGROUND
Human natural killer (NK) cell-mediated cytotoxicity represents a hurdle in pig-to-human xenotransplantation. It was previously reported that the expression of human major histocompatibility complex class I molecules, including HLA-B27, -Cw3, -E, and -G, partially protects porcine endothelial cells (pEC) from human NK-mediated cytotoxicity and that HLA-G inhibits NK adhesion to pEC. Here, we tested if HLA-Cw4 expression on pEC alone, or concurrently with HLA-Cw3, prevents human NK adhesion and cytotoxicity against pEC via recognition of the killer-cell immunoglobulin-like receptors (KIR) CD158a (KIR2DL1) and CD158b (KIR2DL2/3), respectively.


METHODS
Two pEC lines (2A2 and PEDSV.15) were transfected with HLA-Cw3 and HLA-Cw4. HLA and KIR expression on porcine and human cells were analyzed by flow cytometry. The effect of HLA expression on pEC on human NK-mediated cytotoxicity and adhesion was tested by (51)Cr-release and dynamic adhesion assays, respectively.


RESULTS
HLA-Cw4 expression on pEC reduced cytotoxicity mediated by CD158a(+) polyclonal human NK cells by an average of 58%, and by CD158a(bright) NK cell clones by 68%, but not by NK cells expressing low levels of CD158. Co-expression of HLA-Cw3 and HLA-Cw4 on pEC did not mediate further protection against NK cytotoxicity. The expression of HLA-Cw4 reduced the adhesion of human NK cells on pEC by a mean of 53%.


CONCLUSIONS
While transgenic expression of HLA-Cw4 on pEC reduces NK cell adhesion and cytotoxicity, co-expression with HLA-Cw3 is not sufficient to completely overcome human NK-mediated cytotoxicity in vitro.
Forte
Pietro
P
Laboratory for Transplantation Immunology, Department of Internal Medicine, University Hospital Zürich, Zürich, Switzerland.
Baumann
Bettina C
BC
Schneider
Mårten K J
MK
Seebach
Jörg D
JD
D000818:Animals; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology*; D015236:HLA-C Antigens / Q000378:metabolism*; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D054342:Receptors, KIR2DL1 / Q000378:metabolism*; D054344:Receptors, KIR2DL3 / Q000378:metabolism; D013552:Swine / Q000276:immunology*; D014183:Transplantation, Heterologous
D015236:HLA-C Antigens; C038653:HLA-C*03 antigen; C039966:HLA-C*04 antigen; D054342:Receptors, KIR2DL1; D054344:Receptors, KIR2DL3