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Biomedical subjects

S Pestka

Publications and source records attributed to S Pestka.

At least 127 records · Page 7Linked to original sources
PubMed1987

Modulation of human tumor antigen expression.

With membrane-enriched fractions prepared from human metastatic breast tissue used as immunogen, a group of monoclonal antibodies (MAbs) were generated that recognized several distinct antigens on breast and other carcinomas. The antibodies were found to react with established human tumor cells in culture as well as in immunohistochemical protocols using sections of primary and metastatic lesions. One MAb, B72.3, demonstrated a high degree of selective reactivity for human carcinomas in that no reactivity was found with a large number of different normal tissues. These MAbs were used to demonstrate the heterogeneity of expression of the tumor antigens as well as the intrinsic cellular factors (i.e., cell-cycle kinetics and clonal variability) that modulate their expression. Additional studies showed that recombinant human leukocyte interferon can act as a potent regulator of surface antigen expression on human carcinoma cells. Analysis of these cells by radioimmunoassay or flow cytometry revealed that interferon treatment resulted in a higher percentage of the cell population that bind the MAb to the surface antigen. Furthermore, interferon treatment also increases the level of expression for particular tumor antigen throughout the tumor cell population. Experimental models were also developed to investigate the active localization of a radiolabeled MAb by a human tumor xenograft in athymic mice. The results demonstrate active uptake of an 125I-B6.2 by a transplantable human breast tumor that expressed significant quantities of the B6.2-reactive 90 kD tumor antigen. In contrast, a human melanoma cell line grown as a solid, subcutaneous tumor in athymic mice did not localize the labeled B6.2 and does not express the associated 90 kD antigen. We report the generation and characterization of anti-breast carcinoma MAbs. These immunologic probes were used to study relevant breast tumor antigens, the factors that influence their level of expression, and the ability of human tumors grown in athymic mice to localize radiolabeled antibodies.

Animals↗
PubMed1986

Preparation of 32P-labeled murine immune interferon and its binding to the mouse immune interferon receptor.

Murine immune interferon (Mu-IFN-gamma) can be radiolabeled with [gamma-32P]ATP by the catalytic subunit of cAMP-dependent protein kinase. The resulting 32P-labeled Mu-IFN-gamma (32P-Mu-IFN-gamma) with high radiological specific activity (60-260 muCi/micrograms) retains biological activity. Acid hydrolysis of 32P-Mu-IFN-gamma or 32P-labeled human IFN-gamma leads to the release of [32P]phosphoserine but not phosphothreonine or phosphotyrosine. With 32P-Mu-IFN-gamma, we have demonstrated that there are 5 X 10(3) to 1.5 X 10(4) receptors per-cell on several murine cell lines of diverse origin and that the Kd at 24 degrees C for these cells is in the range of 1 X 10(-10) to 1 X 10(-9) M. Covalent binding of 32P-Mu-IFN-gamma to its receptor results in the formation of several specific high-molecular weight products, the major one of which has an apparent molecular weight of 90,000-100,000. If this represents a 1:1 complex of Mu-IFN-gamma and its receptor (or its binding subunit), the murine interferon gamma receptor has a molecular weight of 75,000-85,000.

Adenosine Triphosphate↗
PubMed1986

The gene for the human immune interferon receptor is located on chromosome 6.

When 32P-labeled human recombinant immune interferon gamma (Hu-[32P]IFN-gamma) is crosslinked to human cells with disuccinimidyl suberate, a complex with a molecular size of approximately equal to 117,000 Da was identified by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The formation of this complex is inhibited when the binding is performed in the presence of excess unlabeled Hu-IFN-gamma. The specific formation of the 117,000-Da complex is not observed in mouse L cells or Chinese hamster ovary cells. This complex shows all of the criteria that identify it as the Hu-IFN-gamma receptor or its binding subunit. The same complex can be formed following binding and covalent crosslinking of Hu-[32P]IFN-gamma to some hamster-human or mouse-human somatic cell hybrids. The presence of human chromosome 6 in the hybrids is necessary and sufficient for the formation of this complex. More specifically, the long arm of chromosome 6 seems sufficient. Therefore, we have localized the gene for the Hu-IFN-gamma receptor (or its binding subunit) to the long arm of human chromosome 6. The presence of this chromosome in the somatic cell hybrids is not adequate, however, to confer antiviral resistance to the hybrids in the presence of Hu-IFN-gamma.

Biological Assay↗