Necrotic feature of the trophoblasts lacking HLA-G expression in normal and pre-eclamptic placentas.
OBJECTIVE
Human leukocyte antigen (HLA)-G is thought to be expressed in all placental extravillous trophoblasts (EXTs). In pre-eclamptic placentas, a lack of HLA-G expression on EXTs had been found, and deduced as a possible cause of pre-eclampsia. However, a subset of EXTs lacking expression of HLA-G can also be found in normal placenta. Therefore, we sought to compare these cells in normal and pre-eclamptic placentas.


METHODS
Frozen sections of normal and pre-eclamptic placentas were examined by immunohistochemical staining using HLA-G monoclonal antibody 87G, histochemical enzymatic analysis of succinate dehydrogenase (SDH) and ultrastructural analysis.


RESULTS
A subset of EXTs lacking HLA-G expression was found in both normal and pre-eclamptic placentas. These cells showed necrotic features such as the swelling of cells, eosin-achromatophilia, the loss of SDH activity and swelling mitochondria. Cells from both tissues were identical with regard to these features.


CONCLUSIONS
The features of the EXTs lacking HLA-G expression indicated they had undergone necrosis and thus could not express HLA-G protein. Therefore, an alternative interpretation to the lack of HLA-G expression in pre-eclamptic placentas is that it is the result of cell death and not the cause.
Sageshima
Noriko
N
Department of Legal Medicine, Nara Medical University, Nara, Japan.
Ishitani
Akiko
A
Omura
Motoko
M
Akasaki
Masayoshi
M
Umekage
Hideshi
H
Katabuchi
Hidetaka
H
Okamura
Hitoshi
H
Hatake
Katsuhiko
K
D005260:Female; D006680:HLA Antigens / Q000096:biosynthesis*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D020014:K562 Cells; D008854:Microscopy, Electron; D009336:Necrosis; D010920:Placenta / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D011225:Pre-Eclampsia / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D014327:Trophoblasts / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D014407:Tumor Cells, Cultured
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I