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PubMed1987

Cortical thymocyte differentiation in thymomas: an immunohistologic analysis of the pathologic microenvironment.

Four monoclonal antibodies (BH11, T2/30, AG3, and BC3) were produced against different epithelial components of the normal thymus. An immunohistologic study was performed on 13 thymomas by the use of these and other stromal and lymphocyte-specific reagents. The aim of this study was to find possible relationships between the proliferating thymoma epithelial cell type and the T cell composition of thymomas. Our results indicate that cortical T cell differentiation is present in thymomas, and that this differentiation is induced in the absence of detectable levels of MHC class II antigens on the epithelial component in most cases. The role of the MHC class II antigens cannot be excluded, however, because these antigens were always present on macrophages. Analysis of the selected group of thymomas, each of which contained epithelial cells homogeneously stained by at least one of the described monoclonal antibodies, showed that the cortical type T cell inducer capacity of thymomas is independent of the epithelial type predominant in the tumor.

Antibodies, Monoclonal↗
PubMedDate not supplied

[The role of the hematopoietic microenvironment in the mechanism of the antiradiation action of prodigiozan].

Preliminary administration of a radioprotective dose (3 mg/kg) of the bacterial polysaccharide prodigiozan 24 hours before irradiation of (CBA X X C57B1) F1 hybrid mice by a dose of 8 Gr increased the efficacy of exogenous clone formation of intact and irradiated bone marrow significantly. The efficacy of exogenous clone formation increased by 44-82% in transplantation of intact bone marrow and by 180-220% in transplantation of irradiated marrow (as compared to the values in animals who did not receive prodigiozan). This phenomenon was evidently associated with intensified reproduction of the transplanted CFU in mice given prodigiozan, evidence of which is the quantitative dependence of the effect on the dose of the transplanted cells. A conclusion is drawn that one of the aspects of the hematopoiesis-stimulating effect of prodigiosin in an irradiated organism is linked with its effect on the elements of the hematopoietic stroma. It is suggested that agents of other classes may be characterized by a similar mechanism of action; the same effect may be produced by some other factors which reduce radioresistance.

Animals↗
PubMed1989

[The role of the thymus in regulating the stromal cells responsible for the transfer of the hemopoiesis-inducing microenvironment in stress].

The role of thymus in the regulation of stromal elements, responsible for haemopoiesis inducing microsurrounding transfer of animals, subjected to 10-hours immobilization, was studied. The development of bone marrow hyperplasia and stimulation of functional activity of stromal cells, responsible for haemopoiesis inducing microsurrounding transfer, were shown to be thymus dependent processes during stress.

Animals↗
PubMed1989

Blood flow, metabolism, cellular microenvironment, and growth rate of human tumor xenografts.

Better understanding of the micromilieu of human tumors in situ is mandatory for further improvement of diagnostic and therapeutic interventions. Since investigations of untreated tumors of a wide size range are precluded in humans for ethical reasons, size-dependent changes in the pathophysiology of primary and metastatic human tumors were studied using "tissue-isolated" xenografts in nude rats. Tumor types included lung and breast cancers, ovarian and thyroid carcinomas, uterus tumors, and melanomas. A 10-fold variation in weight-adjusted tumor perfusion indicated large variations in angiogenesis which were unrelated to tumor type. Flow values obtained were consistent with data from clinical observations and were comparable to that in isografted rodent tumors. Using actual consumption and supply rates, maximum oxygen and glucose uptake rates were calculated for each tumor type. The capacity to consume oxygen and glucose varied 9-fold and 4-fold, respectively. However, considering actual consumption rates, blood flow was the principal modulator of substrate supply and tumor metabolism in these human tumor xenografts. Consequently, therapeutically relevant parameters of the metabolic micromilieu largely depended on the efficacy of the tumor circulation. Hereby, high metabolic rates concomitant with high flow values coincided with rapid tumor growth. Thus, in order to design the best individualized therapy, flow-related data should supplement histological classification and clinical staging and grading. Further development of relatively noninvasive technologies (magnetic resonance imaging, magnetic resonance spectroscopy, or positron emission tomography) might permit such monitoring.

Animals↗
PubMed1988

Microenvironment of two different extrinsic fluorescence probes in Na+,K+-ATPase changes out of phase during sequential appearance of reaction intermediates.

Na+,K+-ATPase from pig kidney was sequentially modified with N-[p-(2-benzimidazolyl)phenyl]maleimide (BIPM) at Cys-964 and fluorescein isothiocyanate (FITC) at Lys-501. The resulting preparation showed little Na+,K+-ATPase activity with retention of nearly 90% of phosphorylation capacity from acetyl phosphate. The addition of acetyl phosphate to the preparation induced phosphoenzyme formation with a sequential decrease in the fluorescence intensities in the presence of 2 M NaCl and 4 mM MgCl2; the BIPM fluorescence decreased with a simultaneous increase in the amount of phosphoenzyme; there was a significant delay in a decrease in the FITC fluorescence. The extent of the decrease in the BIPM fluorescence and the increase in the amount of phosphoenzyme both showed monophasic kinetics with a similar dependence on the concentration of acetyl phosphate (K0.5 = 4 mM), while that of FITC fluorescence showed a biphasic decrease (K 0.5 greater than 10 mM). The phosphoenzyme formed was insensitive to ADP but sensitive to acetate (K0.5 = 2 M). These data and those of others (Taniguchi, K., Suzuki, K., Kai, D., Matsuoka, I., Tomita, K., and Iida, S. (1984) J. Biol. Chem. 259, 15228-15233) showed that the extent of the decrease in the BIPM fluorescence reflects an increase in the amount of a precursor of E1P and E1P, irrespective of the FITC treatment. They also suggest the presence of at least two conformationally different E1Ps; one gave little and the other gave a large FITC fluorescence decrease.

Acetates↗
PubMedDate not supplied

Influences of the microenvironment on B-cell responses of wasted mice: comparison of Peyer's patches and mesenteric lymph nodes.

Wasted mice bear an autosomal recessive mutation (wst/wst) that gives rise to neurologic abnormalities and immunologic deficiency evident as early as 21 days of age. Features of the immune deficiency include absence of plasma cells at mucosal sites, reduction in weight of thymus and spleen relative to body weight, and low serum levels of some immunoglobulin (Ig) isotypes. In these experiments, we have examined parameters of B-cell function in Peyer's patches (PP) and mesenteric lymph nodes (MLN) of wst/wst and age-matched control mice. Our results established the following abnormalities in PP but not MLN of wst/wst mice relative to controls: (1) reduced mitogenic responses to lipopolysaccharide, (2) decreased percentages of Ig+ cells, (3) increased percentages of B-cells bearing large amounts of surface Ig ("very bright" Ig+ cells), and (4) reduced levels of all Ig-specific messenger ribonucleic acids (mRNAs) except alpha-mRNA. The only immunologic abnormality consistently expressed in lymphocytes from both MLN and PP of wst/wst mice is reduced levels of IgA+ B cells and alpha-mRNA. Morphologic studies revealed no consistent abnormalities in lymph nodes, spleens, livers, or PP of wst/wst mice when compared to littermate controls. These results support the idea that some of the immunologic abnormalities reported in wst/wst mice are due to microenvironmental influences. Of the parameters examined in this report, only reduced IgA (mRNA levels and percentage of positive cells) is consistently observed in PP, MLN, and spleen.

Animals↗
PubMed1988

Inability of adult circulating haemopoietic stem cells to sustain haemopoiesis in mouse fetal liver microenvironment.

Liver rudiments were removed from mouse embryos at Day 9 of gestation, before the 28-somite stage, when they are still not colonized by extrinsic haemopoietic stem cells (HSC), and they were grafted under the kidney capsule of syngeneic adult mice. Hepatocytes differentiated normally, but no colonization by HSC occurred. As control, we used precolonized thymic rudiments taken at Day 10 of gestation, when they are still included in the third branchial arches. They were grafted in the same conditions as liver rudiments and they became colonized by extrinsic HSC that gave rise to lymphocytes. So, adult HSC are not able to colonize the fetal liver rudiment while they have the capacity to home the fetal thymus. We discuss these results in terms of an ontogenic maturation of HSC that could change their homing capacities around birth.

Animals↗
PubMed1988

Direct evidence for a stem cell common to hematopoiesis and its in vitro microenvironment: studies on syngeneic (inbred) Wistar Furth rats.

When injected into a group of lethally irradiated syngeneic (inbred) Wistar Furth (WF) rats, suspensions of stromal cells grown in monolayer culture from the marrow of WF rats produced hemopoietic colonies in the spleen and rescued 50% of the rats, while 90% of the non-injected (control) rats died within 30 days and had no hemopoietic colonies in the spleens. Fifty percent of the injected (test) rats which died between days 6 and 22 showed hemopoietic regeneration in the bone marrow, while little or no evidence of hemopoietic regeneration was seen in the control animals. Our results suggest that the marrow stroma grown in vitro contain cells with hemopoietic potential and are transplantable.

Animals↗
PubMed1986

Analysis of the thymic microenvironment by monoclonal antibodies with special reference to thymic nurse cells.

Two hybridoma cell lines secreting monoclonal antibodies against stromal tissues of mouse thymus were produced using the spleen cells of BALB/C mice immunized with newborn thymic homogenate of C57BL/6 mice emulsified in Freund's complete adjuvant. The monoclonal antibody Th-3 reacted with stromal cells in the thymic cortex and the monoclonal antibody Th-4 reacted with stromal cells in the thymic medulla. The stromal cells revealed by Th-3 showed a meshwork structure in the cortex, and formed a monolayered border at the cortical surface and around the vasculature. Each mesh of this structure was connected to each other, forming a complex labyrinth and being open toward the medullary area. Neither lymphoid cells nor any cells in any other organs were reacted with this Th-3 antibody. However, the reactivity of Th-3 with the thymic cortical stromal cells was observed not only in C57BL/6 mice which had been used as source of antigen, but also in other strains of mice such as C3H and BALB/C. Immunoelectron microscopy revealed that Th-3 monoclonal antibody was reactive with some component, diffusely present in the cytoplasm of cortical epithelial cells. The pattern of Th-3 positive meshwork in the thymic cortex was quite similar to that stained by either anti-IA or anti-IE antibody, but the Th-3 positive reaction was not inhibited by these anti-IA and anti-IE antibodies. Thymic nurse cells prepared by the method of Wekerle were positive for Th-3 antibody. On the contrary, Th-4 reacted only with epithelial cells in the thymic medulla. It was suggested that Th-3 monoclonal antibody detected some antigen specific to so called thymic nurse cells.

Animals↗
PubMed1985

The microenvironment of coeliac disease: T cell phenotypes and expression of the T2 'T blast' antigen by small bowel lymphocytes.

Peroral jejunal biopsies were studied by double-label immunofluorescence on cryostat tissue sections from control patients of normal histology and patients with coeliac disease. A panel of monoclonal antibodies was used to identify T cells and T cell subsets, together with antibody markers of cell stimulation (the T2 40 kdalton T blast specificity), proliferation (T9 and Ki67) and activation (HLA-DR and Ig receptors). In normal mucosa, expression of T2 was predominantly found in the T8+ intraepithelial cytotoxic/suppressor population. In coeliac disease there was little alteration of T4:T8 ratios per se, but a much higher percentage of T8-T4+ helper/inducer cells expressed the T2 antigen (approx. 30% compared to approx. 10%), manifest as an accretion of T2+T8- cells in the epithelium and subjacent stroma. Additionally, T cell lymphoid aggregates were observed in the lamina propria, consisting of greater than 90% T4+ cells, of which the majority (60-80%) were also T2+. The increase of stimulated helper cells correlated well with the pathology of coeliac disease, being most marked in untreated cases of maximal tissue damage, and least in well treated cases with restoration of normal morphology. By contrast, an increased tendency for the T8+ cells to co-express T1 in untreated coeliac disease was not observed in treated disease, even in cases where failure to adhere to a strict gluten free diet had resulted in little histological improvement. There was little evidence of T cell activation or proliferation. The observation that T helper cells undergo migration and stimulation suggests an imbalance in immunoregulation which causes a breakdown of normal immune tolerance to dietary gluten, and therefore may be a crucial mechanism of tissue damage in coeliac disease.

Adolescent↗