Summary 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 Specifically, sections were washed in two changes of tris buffered saline (TBS) pH 7.6 and then covered with 10% normal horse serum in TBS for 20 min. After draining, the slides were incubated with neat culture supernatant for 30 min in a moist chamber. 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. After three washes in TBS, peroxidase was visualised using a freshly prepared and filtered solution of diaminobenzidine tetrahydrochloride (DAB-Sigma) in TBS containing 0.03% hydrogen peroxide (6 min). Sections were washed in tap water and counterstained in Coles' haematoxylin, dehydrated, cleared and mounted (Ralmount-R.A. Lamb). 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. Reactivity of mAb 5T4 with fixed and paraffin wax embedded sections of term placental trophoblast was also 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 + + + ). Very weak or equivocal reactions were scored + /-.Flow cytometric analyses of human bone marrow cells labelled in PBS, 1% BSA 0. 1% azide with 5T4 mAb followed by 1/20 rabbit anti-mouse Ig-FITC (Serotec, Bicester, UK) was performed on a Becton-Dickenson FACS analyser. The purified mAb 5T4 at 10 ig ml-' was tested for interference with the growth of human pluripotential haematopoietic colonies as described by Welte et al. (1985). RadioimmunoassaySyncytiotrophoblast microvillous plasma membranes (StMPM) were prepared as previously described (Hole &

Summary A urinary gonadotrophin peptide (UGP) was isolated and purified from semi-purified human chorionic gonadotrophin (hCG), prepared from pregnancy urine. The peptide showed hCG-B subunit activity and no hCG-alpha subunit activity as demonstrated by binding studies with the relevant antibodies. It had a molecular weight significantly less than hCG-B subunit. The peptide was linked to thyroglobulin and this conjugate used to immunise rabbits and mice. A radioimmunoassay (RIA) using 1251-UGP and the rabbit antiserum (AK 12) was used to monitor chromatographed urine fractions from patients with ovarian carcinoma, seminoma and hydatidiform mole. UGP was also found in the urine extract of a healthy male, but at a much lower level. In each case the UGP detected had the same molecular weight as the pregnancy preparation and appeared to be the main gonadotrophin constituent in those urine samples. Initial immunohistochemical screening of normal and neoplastic tissues with the rabbit antibody (AK12) showed reactivity with some tumours including carcinomas of the lung, ovary, cervix and breast as well as trophoblastic and germ cell tumours. Reactions with non-neoplastic tissues were confined to some specialised epithelia and macrophage populations. A more comprehensive immunohistochemical study was made using a monoclonal antibody to UGP (2C2), with a monoclonal antibody to conformational hCG (INN 13) and another monoclonal antibody to free B subunit (1 E5) as controls. Similar patterns of reactivity were produced by the AK12 and 2C2 antibodies in both neoplastic and non-neoplastic tissues. Additional tissues were investigated with the three monoclonal antibodies. The 2C2 antibody reacted with 93% (77/83) of tumours examined; the INN 13 antibody reacted with only the syncytiotrophoblast cells of choriocarcinoma, hydatidiform mole, placental site trophoblastic tumour, and in one case of seminoma; the 1E5 reactivity was confined to only choriocarcinoma syncytiotrophoblast cells.

No abstract

Summary Tumour localisation of anti-tumour antibodies varies greatly between patients. Factors which may be responsible for this have been investigated in 56 patients with colorectal carcinoma with a view to improving radioimmunotherapy. Thirty-seven to seventy-four MBq of 1254-labelled mouse monoclonal antibody to CEA, was given intravenously and tumour resected 70-480 h later. Percentage injected activity kg-' (% inj.act kg-') in tumour, was inversely correlated with the time interval between injection and operation (P = 0.004). To assess the influence of other parameters on localisation, patients were divided into two time groups according to time interval between injection and operation, 70-120 h (n = 33) and 144-480 h (n = 23). In neither group was there a significant correlation of % inj.act kg-' with time. The % inj.act kg-' in tumour showed a significant correlation with that in the blood for both groups (P = 0.005 and P = 0.01). There was no significant correlation for either time group between % inj.act kg- ' (Begent et al., 1985;Martin et al., 1988;Begent, 1990). There is great variability in uptake of antibody in individual tumours in patients and the factors influencing this are poorly understood. Distribution of injected antibodies within tumours is not uniform (Griffith et al., 1988;Pedley et al., 1990

No abstract