Inhibition of murine renal carcinoma pulmonary metastases by systemic administration of interferon gamma: mechanism of action and potential for combination with interleukin 4

We have previously demonstrated that IFN-gamma causes cell growth inhibition and up-regulation of MHC antigens in human renal cell carcinoma cell lines. In this study, we have investigated the therapeutic potential of IFN-gamma for the treatment of 5-day established pulmonary metastases induced by i.v. injection of Renca cells, a murine renal adenocarcinoma. We found that systemic injections of IFN-gamma significantly reduced the number of lung metastases in a dose-dependent manner and increased mouse survival. Histological evaluation of IFN-gamma-treated lungs showed residual small tumor nodules containing extensive necrosis and mononuclear infiltrates. Immunohistochemistry studies on lung sections showed macrophage infiltration into tumor nodules, and in vivo depletion of macrophages partially inhibited IFN-gamma antitumor effect, suggesting a role for the macrophages in tumor destruction. Lymphocyte depletion of either natural killer (NK) cells or CD4+ or CD8+ T-cell subsets or both T-cell subsets did not affect the IFN-gamma effect, whereas depletion of both NK and T cells decreased the antitumor activity of IFN-gamma. These data indicate that neither T cells nor NK cells are essential for this activity but that either lymphocyte population can contribute to the IFN-gamma effect. An optimal dose of IFN-gamma inhibited by 60% the growth of Renca cells treated for 3 days in vitro, but this effect was transient and less pronounced in a long-term colony assay, suggesting that IFN-gamma direct growth inhibition may play a role but may not be sufficient to mediate its antitumor effect in vivo. In vitro, IFN-gamma caused up-regulation of class I MHC antigens and induction of class II antigen expression in Renca cells, an effect that may enhance Renca immunogenicity but may be relevant only when a T-cell response is elicited. A sequential administration of IFN-gamma followed by interleukin 4 was therapeutically better than IFN-gamma alone for the treatment of advanced pulmonary metastases, probably due to different antitumor mechanisms induced by these two cytokines.     

Allelotyping of endometriosis with adjacent ovarian carcinoma reveals evidence of a common lineage

Endometriosis is a common gynecological disease in which tissue similar to the endometrium proliferates at sites outside the uterine cavity. Malignant transformation of endometriosis to endometrioid and clear cell ovarian carcinomas has been documented in histological studies, but no molecular genetic evidence exists to support that endometriosis is the clonal precursor of such malignancies. We examined 14 cases of endometriosis synchronous with ovarian cancer for loss of heterozygosity on 12 chromosome arms, X chromosome inactivation, and TP53 mutation to determine whether they shared genetic alterations. In all four of the cases where the carcinoma had arisen within endometriosis and in five of the seven cases where the carcinoma was adjacent to the endometriosis, common genetic lesions were detected, consistent with a common lineage. A TP53 mutation was also detected in one case of endometriosis adjacent to carcinoma. These findings support the numerous histological observations that endometrioid and clear cell ovarian carcinomas may arise through malignant transformation of endometriotic lesions.     

Na+,K+-ATPase inhibitors in rat urine: origins and physiological significance

To identify the origins and structures of mammalian tissue-derived Na+,K+-ATPase inhibitors, we investigated the tissue distribution of inhibitors in rats. Among many tissues tested, urine was found to contain high levels of many inhibitors. The structures of the two major inhibitors were identified as neoconvalloside and periplogenin monorhamnoside, which are derivatives of strophanthidin. Urinary levels of these inhibitors, however, decreased considerably after changing the diet from the regular diet to purified synthetic diet, suggesting that the majority of the urinary inhibitors are of dietary origin. Investigation of the ingredients of the diet further revealed that alfalfa meal and ground oats are the major sources of these cardiac glycosides. As to the physiological relevance of the cardiac glycosides, a low concentration (1-50 nM) of ouabain dose-dependently enhanced aldosterone secretion from adrenal glomerulosa cells by an increase in local renin release. Ouabain was also found to be involved in AT2 receptor-specific expression in rat PC12W cells through an increment in intracellular Na+. These results suggest that Na+,K+-ATPase inhibitors, regardless of the source, are involved in the regulation of blood pressure.     

The use of nonhomologous scatchard analysis in the evaluation of ligand-protein interactions

Scatchard plots are widely used for the graphical presentation of receptor-ligand binding data. When a combination of labelled and unlabelled ligand molecules is used in a binding assay, equations for Scatchard plots are readily available if the labelled and unlabelled ligands have similar binding affinities. In this article, Everardus van Zoelen, Roel Kramer, Herman van Moerkerk and Jacques Veerkamp present mathematical equations to obtain the binding characteristics of an unlabelled ligand in a Scatchard plot, which has a dissociation equilibrium constant different from that of the labelled ligand used.     

Urban mortality--race or place?

Several concomitant trends have occurred in American society in the 20th century. First, life expectancy has improved overall, and the gap between blacks and whites has narrowed. Second, as the nature of the economy has changed from rural agrarian to urban postindustrial, there have been fundamental changes in population residential patterns, with most Americans now living in metropolitan areas. Within metropolitan areas, blacks have become concentrated in poor inner cities as whites have moved to the more affluent suburbs. Black mortality rates are higher in big cities than elsewhere, and appear to be directly related to the proportion of blacks in those cities. Black-white mortality ratios, however, are lower in cities of medium size than in either very large or small cities. At the national level age-adjusted mortality ratios between blacks and whites are associated with different causes of death; but only limited cause-specific mortality data are available for large cities. Understanding and ameliorating social conditions that lead to elevated black mortality in U.S. cities will require more information at the municipal level than is currently available.     

Differential effects of peptide diversity and stromal cell type in positive and negative selection in the thymus

Thymocyte positive selection results in maturation to the single-positive stage, while negative selection results in death by apoptosis. Although kinetic analyses indicate only 3-5% of CD4+ 8+ cells reach the single-positive stage, the balance of positive and negative selection and the nature and quantity of cells mediating maximal negative selection are uncertain. Here, using a system where the number and type of stromal cells and thymocytes can be controlled, we investigated the maturation of CD4+ 8+ thymocytes in the presence or absence of thymic epithelium and dendritic cells (DC) from wild-type (wt) and H-2M(-/-) mice expressing different peptide arrays. We find that titration of wt DC into reaggregates of wt epithelium has a dramatic effect on the number of CD4+ cells generated, with 1% DC causing a maximal 80% reduction. Moreover, while addition of 1% wt DC into cultures of H-2M(-/-) epithelium causes a 90% reduction in CD4+ cells, no effect was observed when similar numbers of wt thymic epithelium were added. Collectively, these data provide the first accurate indication of the quantity and quality of stromal cells required for maximal negative selection in the thymus, demonstrate the importance of peptide diversity in T cell selection, and highlight a large degree of overlap between positive and negative selection events.     

Identification of epitopes of fibronectin attachment protein (FAP-A) of Mycobacterium avium which stimulate strong T-cell responses in mice

The T-cell response to fibronectin attachment protein (FAP-A) in BALB/c and B10.BR mice was examined. Both strains developed strong T-cell responses to FAP-A, directed to single, unique epitopes. T cells from mice infected with Mycobacterium avium responded to FAP-A, suggesting a possible role in a protective immune response.