The expression of HLA on two cultured choriocarcinoma cell lines

Since gestational choriocarcinoma is believed to be derived from trophoblast, paternal antigens are expected to be present on carcinoma cells. Two choriocarcinoma lines (GCC-SV and Lu-75) transplantable in nude mice were obtained and cultures were started in order to study the expression of HLA on these tumor cells. To date, two human chorionic gonadotropin-producing cell lines, designated GCC-SV(c) and Lu-75(c), have been maintained for over two years with more than 15 passages and have been employed for serological studies. First, GCC-SV(c) (patient A2, AW30, B8, B10; husband A3, AW26, BW16, BW35) was tested by protein A assay with HLA-A typing sera and anti-beta 2 microglobulin; the phenotype was A2+, A3-, AW26-, beta 2+, which corresponded to HLA-A type of the patient. In contrast, HLA-A was not demonstrated on Lu-75(c) cells (patient A2, BW35, BW39; husband A9, AW26, BW22) by the direct test, but anti-beta 2 microglobulin serum gave a positive reaction. A mouse monoclonal antibody against HLA was also employed, but it did not react against Lu-75(c) cells. Further serological analysis was carried out by means of absorption tests, and it was confirmed that GCC-SV(c) was A2+, A3-, AW26- and Lu-75(c) was A2-, A9-, AW26-. The results so far obtained do not demonstrate the expression of paternal HLA-A antigens on choriocarcinoma cells.