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ny's reaction. Materials and methods. To provoke the Ouchterlony's precipita- tion reaction we used some specific ~Kyperimmunic serum against the proteins in the blood serum of pigs, homogenats of placenta, of chorion, of allentoid and amnion fluid of foetus of the se- cond month of pregnancy. Results of researching. By the method of precipitation in agar we found a positive reaction of the antigen-antibody between the anti-serum against the proteins in blood serum, placed in the central hollow and the placenta homogenats, chorion, allantoid, allantoid and amnion fluid, placed in peripheral hollows. We found some serological identity of analyzed antigens. All analyzed antigens created one identical precipitation belt; but homogenat chorions, homogenat allantoid, allantoid fluid, homo- genat amnian, amnion fluid created 3-4 identical arcs of preci- pitation. Moreover, in allantoid fluid there were found some additional antigens which were identical to the analyzed anti- gens.

THE EXPRESSION OF CLASS I MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) ANTIGENS BY HUMAN NON-VILLOUS TROPHOBLAST. C.W.G. Redman, GIM. Stirrat and C.A. Sunderland.

Department of Obstetrics & Gynaecology, The John Radcliffe Hospital, Headington, Oxford. OX3 9DU, U.K.

A panel of monoelonal antibodies to monomorphic and polymorphic Class I MHC determinants has been used with the indirect immunoperoxidase technique to determine antigen expression on human trophoblast. At all stages of pregnancy villous trophoblast does not express Class I MHC antigens. In contrast, various populations of non-villous trophoblast exhibit these determinants. In early pregnancy they include the cytotrophoblast cell columns, and the interstitial and endovascular trophoblast of the placental bed. In late pregnancy they include interstitial giant cells, trophoblast in the decidua basalis, and some trophoblast of the amniochorion. These cell populations react similarly with antibodies to different monomorphic Class I MHC determinants and to B2 microglobulin. However in tissue taken from conceptuses of the appropriate HLA-A or -B types the non-villous trophoblast consistently fails to bind polymorphic antibodies to HLA-A or -B. This suggests that the HLA determinants on human non-villous trophoblast are either HLA-C or some other unidentified MHC Class I antigen.

EXPRESSION OF TROPHOBLAST MEMBRANE ANTIGENS ON MALIgNAMT TISSUES AND CELL LINES. Subrata Sinha, Alok Bhattacharya, A.H. Band, Amitabh Caur, L.M. Srivastava and G.P. Talwar. Department of Biochemistry, All India Institute of Medical Sciences and National Institute of Immunology, New Delhi-l10029, India.

Plasma membranes were prepared in a purified form by gradient centrifugation from term placenta villi. Their purity was checked by assays for marker enzymes. Antibodies were raised in rabbits and absorbed with different tissues to render them specific for placenta. A solid phase enzyme ~oassay (EIA) was used to measure reactivity of the placenta specific antibody with malignant tissues and cell lines. The anti- trophoblast sert~n was found to react with a majority of breast carcinoma membranes, while it was devoid of reactivity with norm~al breast tissue

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membranes obtained from the s~memastectomy specimens. Reactivity was also seen with MCF-7 a human mammary carcinoma cell line. However, the sera of breast cancer patients had no antibodies reacting with trophoblast membrane in the EIA.

The antiserum reacted with BeWo, a humanchoriocarcinoma cell line, and BeWo cells could absorb out almost all the reactivity to trophoblast plasma membrane, indicating the conservation of trophoblast specific determinants on BeWo. The antiserum was cytotoxic to BeWo in the presence of complement,

IMMUNOHISTOLOGY OF THE HUMAN CHORIONIC VILLUS IN SEARCH OF BLOOD GROUP A AND B ANTIGENS, RH-D ANTIGENS AND HUMAN LYMPHOCYTIC ANTIGENS.

Setsuko Goto, and Yutaka Tomoda. Department of Obstetrics and Gynecology, School of Medicine, Nagoya University, Nagoya,466, Japan. i) The chorionic villi of placentas,10 to 40 weeks of gestation,

were examined for A and B blood group antigens with an immuno- ferritin technique. No specific ferritin attachment was shown on the plasma membrane of the villous trophoblasts. Furthermore, after trophoblast cell-surface mucosubstances were digested with several enzymes, no ferritin tagging was observed on it. 2) The chorionic villi of normal placentas, hydatidiform moles

and destructive moles were examined for Rh-D blood group antigens with direct immunofluorescent(IF) technique. Specific IF-staining was shown on the plasma membrane and cytoplasm of the villous tro- phoblasts. This staining decreased in intensity as the placenta matured. The intensity of the IF-staining in hydatidiform and dest- ructive moles was almost the same as that in the young trophoblasts of the first trimester of pregnancy. 3) The enzyme-labeled antibody method was used to examine dist-

ribution of HLA-ABC and ~2-microglobulin in chorionic villi of normal human placentas and trophoblastic tumors. Specific enzyme staining was observed on plasma membrane of the trophoblast and stroma cell in the villi. The young villi of first trimester of gestation was most strongly stained and the density of enzyme sta- ining decreased as the placenta matured.

LACK OF HLA(ABC AND DR) ANTIGEN EXPRESSION ON THE NORMAL AND ABNORMAL (HYDATIDIFORM MOLE AND CHORIOCARCINOMA) TROPHOBLASTIC CELLS

Kohki Yamashita, Kazuhide Mute, and Tetsuya Shimizu

Department of Obstetrics and Gynecology, Asahikawa Medical College, Asahikawa, 078-11, Japan

Five normal chorionic villi, two hydatidiformmole, two choriocarcino- raa, and five choriocarcinoma cell lines were examined by the 9rmunofluorescent method using monoclonal antibodies and by the inhibition test in order to inv- estigate the expression of HLA(ABC and DR) antigens.

With regard to the normal chorionic villus and the hydatidiform mole, HIA (ABC and DR) antigens were absent from trophoblastic cells, but HLA-ABC antig- ens were present on cells in the villous stroma. With respect to choriocarci- noma cells, HLA(ABC and DR) antigens were virtually negative. One choriocarc- inoma cell line, SCH, which is not a placental origin but a gastric cancer or- igin, showed a slightly positive reaction on HLA-ABC antigens.

These findings suggest that gestational trophoblastic cells, regardless of normal or cancerous cells, my not induce transplantation inmunity.