Immunoradiometric assay of alphafetoprotein using monoclonal radioiodinated antibodies

70 IMMUNORADIOMETRIC ASSAY OF ALPHAFETOPROTEINUSING MONOCLONALRADIOIODINATED ANTIBODIES. J.SERTOUR, D.BELLET~, J.L.SALARD, J.MARCHAND (ORIS/LAPAM CEA Marcoule B.P.171, 3~nols sur C6ze FRANCE ;~ I G R - V i l l e j u i f FRANCE) A new solid phase for immunoassays : ELSA has been perfected in our laborator i e s , forming a suitable compound fo r sandwich techniques. The system we present is a tube into which a coated m u l ti fi n n e d stick has been jammed, which offers both advantages of coated tubes into which a l l steps of the assay are performed and beads with a coating step performed in big batches. This ensures speed, precision, r e l i a b i l i t y . We f i r s t presented i t s application to alphafetoprotein sandwich assays with a polyclonal tracer in a 2 steps incubation (twice 2 hours-37°C) with a working range from 3 to 240 ng/ml AFP (1). We have then introduced a monoclonal antibody in the system with as good an a f f i n i t y constant as the p o l y c l o n a l ' s one and compared the behaviour of both tracers in the same conditions : the standard curve with the monoclonal is less sensitive in the range 3-15 ng/ml but a l o t more in the range 60-240 ng/ml. The precision is much better with the monoclonal a l l a long the standard curve (CV < 6 %). The hook-effect that had been demonstrated with the polyclonal in a simultaneous incubation is delayed from 300 to 750 ng/ml with the monoclonal. We thus came to the conclusion that we should use t h i s monoclonal in our ELSA-AFP assay and we o f f e r now a k i t with which a l l c l i n i c a l values have been proved to be equivalent to those obtained with our present CIS-AFPK. (1) J.Sertour, C.Moulin, F.Coste, B.Ly, JL.Salard, J.Marchand. i n "Radioimmunoassay and related procedures in medicine 1982". IAE~--Vienna, 1982.

HISTOCOMPATIBILITY ANTIGENS, TRANSFERRIN RECEPTORS AND EXTRA-EMBRYONIC OF HUMAN AMNIOCHORION AND CULTURED AMNIOTIC EPITHELIAL CELLS. Chang-Jing G. Yeh, Bae-Li Hsi and W. Page Faulk. INSERM U210, Faculte de Medecine, Avenue de Vallombrose, France.

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06034 Nice-Cedex,

Since it is probably unwise to build hypotheses about reproductive immunology on the basis of data accumulated from only the placental interface, we have studied cells by immunofluorescence at the deciduo-chorial interface for the presence of some of the antigens which have been identified within placenta and amniotic epithelium. For this purpose, we have selected both monoclonal and polyclonal heterologous antisera to beta-2-microglobulin (B2M), HLA transferrin receptors (TrfR), trophoblast antigens (TAI) and two different amnion antigens (AAI and AA2). The tissues investigated in this study were fresh amniochorions, and lines of amniotic epithelium which had been maintained in culture for prolonged periods of time. The results of these studies on intact amniochorions showed that the cytotrophoblast, like its counterpart in placenta, lacks B2M and HLA but manifests TAI, but unlike the villous syncytiotrophoblast, the amniochorionic cytotrophoblast lacks TrfR. Amnion antigens were not found on trophoblast. Similar to cytotrophoblast, amniotic epithelium lacks B2M, HLA and TrfR, but reacted with both AAI and AA2. Striking differences were obtained with cultured amniotic epithelium. These were negative with anti-AA and positive with anti-TAl, B2M, HLA and TrfR, suggesting an inverse relationship between certain plasma membrane antigens of extra-embryonic cells. Whether all gene products which are expressed in culture can also be activated in vivo is not known, but some of them clearly are, as demonstrated by the presence of HLA on trophoblast tumors.