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A totally synthetic molecule (109-145 peptide) analogous to the beta-subunit carboxyl terminus was used as an antigen in the development of antibodies by the hybridoma technique. A monoclonal antibody (702 D7) specifically recognized the free native beta-human CG (beta hCG). 702 D7 was of the immunoglobulin G1 subclass and was directed against an antigenic site localized in a 10-amino acid sequence (109-118) or less. The recognition of an epitope located in the 109-118 region could explain the specific recognition of beta hCG observed with 702 D7, in contrast to monoclonal antibodies directed against a 118-145 region with a recognition of both beta hCG and whole hCG, as observed with a second monoclonal antibody (1032) to synthetic peptide. Immunohistochemical results and preliminary data obtained from the immunoradiometric assay show that 702 D7 provides a clinical tool for the detection of free beta-subunit secretion even at low concentrations, and could allow the study of this subunit or its metabolites produced by normal and tumoral cells.

In order to detect specifically the beta-hCG, we have produced monoclonal antibodies (Mabs), using as immunogens hCG, beta hCG or a totally synthetic molecule (109-145 peptide) analogous to the beta-subunit carboxyl terminus. 34 fusion experiments were performed and led to 8 Mabs which presented a high reactivity to 125I beta hCG in the screening test. Mab D1E8 was directed to the 1-115 region of beta hCG and was cross reactive with hLH (greater than 60%). Mabs 702, 1032, and 1211 were directed against three different epitopes located in the 109-145 region and were specific for the beta hCG. The in vivo localization of tumors containing beta hCG ty tomoscintigraphy (SPECT) was evaluated in 5 patients by injecting 131I-Mab D1E8, selected for imaging because of its high affinity to beta hCG (Ka = 1.9 X 10(9)). SPECT was performed 48 h and 96 h after injection: 2 patients with proven tumor sites had positive "immunoscintigraphy" results. One patient, simultaneously injected with 125I non-specific IgG, had a tumor resection: the count ratio between normal and tumoral tissues revealed a low specific uptake. Two and three-site immunoradiometric assays (IRMA) were performed with monoclonal antibodies purified from nude mice ascitic fluids. IRMA were based upon two or three Mabs, with D1E8 on a solid phase and 125I Mab 702 or a mixing of 125I-702 and 125I-1032 as tracer. The specificity of IRMA was demonstrated by the absence of binding with increasing amount of hLH, hFSH and hTSH up to 5000 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

The HNK-1 antibody known to define a subpopulation of human lymphocytes with natural killer and killer cell activities was shown to detect a common neuroectodermal antigen. Most tumor lines and paraffin-embedded tumors and normal tissues of neuroectodermal origin were specifically stained by HNK-1. Lines and tissues of other derivations were negative except a trophoblastic tumor line and a percentage of Ewing's sarcomas, whose histogenesis is poorly understood. These data indicate that HNK-1 antibody could be of interest in clinical histopathology but cannot be considered as specific for a lymphocyte subset.

We describe immunoscintigraphy using a radiolabelled anti-tumor monoclonal antibody 181-23 in 6 patients with squamous lung cancer. Double-label method using simultaneous injections of 131I MAB and 125I control immunoglobulin was performed to evaluate the specificity of MAB localization in the tumor. Immunohistological localization of MAB in resected specimen was obtained by immunoperoxidase technique. All our data are negative but correlated.

Eleven cases of epithelial tumours of the thymus or thymoma and two thymuses without tumour were studied, using immunohistochemistry with anti-keratin antibodies (KL-1) which recognise cyto-keratin with a high molecular weight. In the normal thymus, KL-1 positivity seems to be limited to medullary epithelial elements and in particular Hassal's corpuscles. All the epithelial thymic tumours studied showed a net positivity for KL-1 overall in the tumour cells. This result and the demonstration of more or less well differentiated Hassal's corpuscles in these tumours make one think that these epithelial thymic tumours express some characters in relation with a differentiation of medullary type.