HLA-G expression by tumors.
OBJECTIVE
It has been proposed that the expression of the non-classical MHC class I antigen, HLA-G, by trophoblast is one mechanism by which the placenta evades attack by maternal uterine NK cells. A similar mechanism is thought to be operative in the escape from immunosurveillance by tumor cells. However, data on the expression of HLA-G by tumor cells are highly conflicting.


METHODS
In the present study, we have examined tissue sections from a wide variety of tumors by immunohistology and also several cell lines by flow cytometry and RT-PCR. Whilst very faint bands were detected in three cell lines (hepG2, Mead, CaSki) by RT-PCR, no tumors or cell lines were observed to express HLA-G protein. Furthermore, we found that tumor deposits are not usually infiltrated by NK cells.


CONCLUSIONS
Our observations, therefore, do not support the proposal that tumor cells express HLA-G in order to evade host NK cell cytolysis.
Davies
B
B
Department of Pathology, University of Cambridge, United Kingdom.
Hiby
S
S
Gardner
L
L
Loke
Y W
YW
King
A
A
D006680:HLA Antigens / Q000032:analysis* / Q000235:genetics; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000032:analysis* / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D007962:Leukocytes / Q000502:physiology; D009369:Neoplasms / Q000737:chemistry* / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger