[Humoral diagnosis of cancer].
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Biomedical subjects
Publications and source records attributed to J P Mach.
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The human melanoma-associated antigen identified by the monoclonal antibody (mAb) Me14-D12 is a cell surface protein whose expression is induced by interferon-gamma (IFN-gamma). We have recently reported the molecular cloning of a genomic probe specific for the gene and mRNA of this protein. By screening with the genomic probe, we have now isolated a full length 3.0 kb cDNA from a Raji cell line-derived lambda-gt10 library. Sequence analysis of this cDNA showed a 99.8% homology with the intercellular adhesion molecule-1 (ICAM-1). Mouse Ltk- cells stably transfected with the human cDNA clone were found to express the ICAM-1 antigenic determinants detected by mAb Me14-D12 and a reference anti-ICAM-1 mAb, as judged by surface immunofluorescence. Immunoprecipitation of surface-iodinated proteins with mAb Me14-D12 revealed the presence of a 90 kD molecule with identical mobility to ICAM-1. In addition, mAb Me14-D12 could inhibit the phorbolester-stimulated aggregation of U937 cells. The findings show that the human melanoma-associated Me14-D12 antigen is the adhesion molecule ICAM-1.
BACKGROUND: A combination of radioimmunotherapy (RIT) and radiotherapy (RT) should allow one to increase the dose of radiation targeting a particular tumour without the concomitant increase of toxic side effects. This might be obtained if the dose limiting side effect of each individual radiation therapy concerned different organs. METHODS: Six patients with limited liver metastatic disease from colorectal cancer were treated with 6.9 GBq (range 4.7 to 8.4 GBq) 131I-labelled anti-CEA MAb F(ab')2 fragments combined with 20 Gy RT to the liver. Both treatments were given in close association, according to timing schedules evaluated in animals that gave the best results. RESULTS: Reversible bone marrow and liver toxicity was observed in 6 and 5 patients, respectively. Three patients who first received 20 Gy RT to the liver, showed a significant platelet drop upon completion of RT. Repeat computerized tomography (CT) after 2 months showed a minor response in 1 patient and stable disease in 3 patients. CONCLUSION: The study shows potential ways of combining RIT and RT, suggesting that this combination is feasible for the treatment of liver metastases.
In order to determine if 5-fluorouracil (5FU) could potentiate the effect of radioimmunotherapy (RIT), nude mice bearing subcutaneous human colon carcinoma xenografts were treated by 1 or 2 intravenous injection(s) of subtherapeutic doses of 131I labeled F(ab')2 from anti-carcinoembryonic antigen monoclonal antibodies combined with 5 daily intraperitoneal injections of 5FU. Control mice received either 131I F(ab')2 alone, 5FU alone or no treatment. RIT alone induced significant tumor regression, while 5FU alone gave only minimal tumor growth inhibition. The combined treatment group also resulted in long-term tumor regression with tumors remaining significantly smaller than in the RIT alone group. There was however, no significant difference in tumor recurrence time between the groups treated with RIT alone or with RIT + 5FU. Myelotoxicity, the major side effect of RIT, detected by the decrease of peripheral white blood cells (WBC), was shown to be almost identical between the groups receiving only RIT or only 5FU. Surprisingly, there was no cumulative bone marrow toxicity in animals which received 5FU before RIT. Furthermore, in the latter group, the WBC levels after RIT were significantly higher than in the control group receiving only RIT. Taken together, the results demonstrate the higher therapeutic efficiency of RIT as compared to 5FU in this model. They do not show, however, that the combination of the two forms of treatment can induce longer tumor remission. Interestingly, the WBC results suggest that 5FU given before RIT can have a radioprotective effect on bone marrow, possibly by selecting radioresistant bone marrow stem cells.
During the development and testing of a radioreceptor assay (RRA) for human IL-1, we have detected and identified the presence of auto-antibodies to IL-1 in normal human plasma (NHP). The RRA is based on the competition between human 125I-labeled rIL-1 alpha and standard or unknown quantities of IL-1 alpha or IL-1 beta for binding to a limited amounts of IL-1 receptor (IL-1R) isolated from the EL4 mouse thymoma cell line. NHP from 20 out of 100 unselected blood donors were found to completely inhibit the binding of 125I-labeled IL-1 alpha to its receptor, suggesting the presence in these NHP samples of either abnormal amounts of IL-1 or of a factor binding to the 125I-labeled IL-1 alpha. Special care was taken to ascertain that the inhibitory factors were antibodies and not soluble IL-1 receptor antagonist. When plasma samples with inhibiting activity were incubated with labeled IL-1 alpha and chromatographed on a Sephadex G200 column, they were found to contain 125I-labeled complexes with an apparent molecular weight of 150-200kD. The IL-1 binding factor could be eliminated from plasma by incubation with protein A-Sepharose, suggesting that it consisted in IgG antibodies directed against IL-1. Furthermore, the antibody nature of the inhibiting factor was confirmed by its binding to purified rIL-1 coupled to Sepharose. Screening of 200 NHP samples by incubation with 100 pg of 125I-labeled IL-1 followed by precipitation with 12% of polyethylene glycol (PEG) confirmed that about 25% of NHP contain detectable IgG antibodies to IL-1 alpha, while only 2% of NHP contain antibodies to IL-1 beta. No correlation between the presence of these anti-IL-1 antibodies and any particular major histocompatibility complex or any pathological conditions was detected. We suggest that all serum samples assayed for IL-1 alpha or IL-1 beta content should be pretested with the PEG precipitation assay described here.
We produced three monoclonal antibodies, BF7, GE2 and CG12, against cultured human glioma cells. Their specificity was tested by an indirect antibody-binding radioimmunoassay on a panel of glial and non-glial tumor cell lines. BF7 and GE2 react preferentially with glioma cells and, except for one colon carcinoma line, they do not bind to the control non-neuroectodermal cells; they appear to be directed against common malignant glioma associated antigens. CG12, the third monoclonal antibody, binds to the great majority of tumor cell lines of neuroectodermal origin and does not bind to any other cell lines tested.