Abstract
A trophoblast cell surface antigen has been characterised by a monoclonal antibody (mAb) 5T4, raised following immunisation with solubilised wheat germ agglutinin binding glycoproteins from human syncytiotrophoblast plasma membrane (StMPM). The expression of the 72 kDa glycoprotein was assessed on cryostat sections of a range of neoplastic and non-neoplastic tissues, using an avidin-biotin immunoperoxidase technique. In products of conception, intense reactions were noted with villous syncytiotrophoblast membrane in normal early and term placenta, with weaker positivity of placental site trophoblast. Most normal or non-neoplastic tissues were negative, including liver, kidney, spleen, small intestine, ovary and testis. Faint or moderate positive reactions were present in some specialised epithelia. Of 115 neoplasms examined, 76 showed reactions with tumour cells including carcinomas of the bladder, breast, cervix, endometrium, lung, oesophagus, ovary, pancreas, stomach and testicular non-seminomatous germ cell tumours. Choriocarcinomas and placental site trophoblastic tumours were also positive. Most adenocarcinomas of colon and seminomas were negative as were all malignant melanomas and malignant lymphomas. A radioimmunoassay did not detect the antigen in either normal or pregnancy serum. The relatively low level of expression in normal tissues and reactivity with a wide range of carcinomas suggested that the antibody may be useful in diagnostic or targeting studies.
Highlights
A panel of normal, non-neoplastic and neoplastic tissues were used
Reactivity of monoclonal antibody (mAb) 5T4 with fixed and paraffin wax embedded sections of term placental trophoblast was assessed by immunoperoxidase. 5T4 mAb reactivity was assessed by P.J.S. and G.M.B. and the intensity of staining was scored on an arbitrary scale ( + to + + + )
All components of normal brain, liver (Figure lc), small intestine, ovary, testis or lymphoid tissues were unreactive with mAb 5T4
Summary
ImmunohisitochemistryA panel of normal, non-neoplastic and neoplastic tissues were used. Sections were washed in two changes of tris buffered saline (TBS) pH 7.6 and covered with 10% normal horse serum in TBS for 20 min. Following three washes in TBS (5 min each), biotinylated anti-mouse Ig (Vector Laboratories) diluted 1/250 in TBS containing 10% normal human serum was applied. After 30 min incubation in the moist chamber, the slides were washed three times and incubated with the avidin-biotin peroxidase complexes reagent (Vector Laboratories) for 50 min. The immunohistochemical results were interpreted with reference to a set of controls run in parallel with each test These included sections treated with DAB only to show endogenous peroxidase, omission of the primary antibody and replacement of the primary antibody with one of the same class but of unrelated specificity.
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