Homeostatic maintenance of T cells and natural killer cells

Homeostasis in the immune system encompasses the mechanisms governing maintenance of a functional and diverse pool of lymphocytes, thus guaranteeing immunity to pathogens while remaining self-tolerant. Antigen-naïve T cells rely on survival signals through contact with self-peptide-loaded major histocompatibility complex (MHC) molecules plus interleukin (IL)-7. Conversely, antigen-experienced (memory) T cells are typically MHC-independent and they survive and undergo periodic homeostatic proliferation through contact with both IL-7 and IL-15. Also, non-conventional γδ T cells rely on a mix of IL-7 and IL-15 for their homeostasis, whereas natural killer cells are mainly dependent on contact with IL-15. Homeostasis of CD4⁺ T regulatory cells is different in being chiefly regulated by contact with IL-2. Notably, increased levels of these cytokines cause expansion of responsive lymphocytes, such as found in lymphopenic hosts or following cytokine injection, whereas reduced cytokine levels cause a decline in cell numbers.     

Reactivity of juxtaglomerular granule cells to changes in sodium and potassium intake in the absence of the adrenal bodies

Résumé Chez les rats adrénalectomisés, une différence très nette de l'indice de la granularité juxtaglomérulaire est apparue entre les animaux qui avaient bu du 2% NaCl et ceux qui avaient reçu ou de l'eau distillée ou du 2% KCl. Il y a donc une réactivité juxtaglomérulaire, indépendente du cortex surrénal.     

Retinoic acid enhances the proliferation of smooth muscle cells

Summary Retinoic acid (RA, 10^–5–10^–7 M) is shown to enhance the proliferation of cultured rat aortic smooth muscle cells (SMC). This effect is not connected with a synergistic action of RA together with serum mitogens. Moreover, the expression of L1, a surface antigen specific for modulated SMC entering the cell cycle, is amplified by RA treatment.     

Retinoic acid enhances the proliferation of smooth muscle cells

Retinoic acid (RA, 10(-5) - 10(-7) M) is shown to enhance the proliferation of cultured rat aortic smooth muscle cells (SMC). This effect is not connected with a synergistic action of RA together with serum mitogens. Moreover, the expression of L1, a surface antigen specific for modulated SMC entering the cell cycle, is amplified by RA treatment.     

Presence of natural killer cells in Peyer's patches of the mouse

Summary Natural cell-mediated cytotoxicity of normal murine Peyer's patch cells against Ehrlich ascites carcinoma was found in a short-term⁵¹Cr release assay. Peyer's patch and lymph node cells showed natural cytotoxicity at approximately the same level.Acknowledgments. This work was supported by grant No. 10.5 from the Polish Academy of Sciences.     

TRAIL promotes the survival,migration and proliferation of vascular smooth muscle cells

Human and rat primary sub-cultured vascular smooth muscle cells (VSMCs) showed clear expression of the death receptors TRAIL-R1 and TRAIL-R2; however, recombinant soluble TRAIL did not induce cell death when added to these cells. TRAIL tended to protect rat VSMCs from apoptosis induced either by inflammatory cytokines tumor necrosis factor- + interleukin-1 + interferon- or by prolonged serum withdrawal, and promoted a significant increase in VSMC proliferation and migration. Of note, all the biological effects induced by TRAIL were significantly inhibited by pharmacological inhibitors of the ERK pathway. Western blot analysis consistently showed that TRAIL induced a significant activation of ERK1/2, and a much weaker phosphorylation of Akt, while it did not affect the p38/MAPK pathway. Taken together, these data strengthen the notion that the TRAIL/TRAIL-R system likely plays a role in the biology of the vascular system by affecting the survival, migration and proliferation of VSMCs.Received 6 May 2004; received after revision 7 June 2004; accepted 8 June 2004     

Cell proliferation in the rat pituitary gland: A mechanism of control in prolactin cells

Summary We investigated the relationship between prolactin content and DNA replication in the anterior pituitary gland. Thymidine incorporation in pregnant rats is significantly lower than in virgin controls. This is accompanied by a decreased activity of DNA polymerase. Sulpiride administration to pregnant rats enhances thymidine incorporation to levels similar to virgin controls. The results indicate a negative feedback between prolactin content and DNA synthesis in the rat anterior pituitary gland.We are grateful to Prof. Carlos J. Gómez for the opportunity to perform this work. These studies were supported by PLA-MIRH 99.178.1.78, by the Consejo Nacional de Investigaciones Científicas y Técnicas and by the Comisión Nacional de Energía Atómica (Argentina).     

Pseudomosaicism in acatalasemic red cells visualized by fluorescent antibody technique

Zusammenfassung Im Blutausstrich lassen sich Erythrozyten von normalem und solche von stark vermindertem Katalasegehalt durch Verwendung von fluoreszierender Antikatalase unterscheiden. Mit dieser Methode konnte der früher erhobene Befund, wonach bei homozygoten Trägern des Enzymdefektes Akatalasie ein Pseudomosaizismus besteht, bestätigt werden. Bei der Untersuchung von Erythrozytenfraktionen verschiedener Dichte besteht eine Korrelation zwischen der Anzahl Retikulozyten und fluoreszierender Zellen. Dieser Befund passt zur Annahme, dass es sich bei der Katalaserestaktivität im Blut homozygoter Defektträger um eine instabile, jedoch antigenidentische Enzymvariante handelt.     

Effect of endotoxin and dietary phosphorus on the proliferation of liver reticuloendothelial and bone marrow cells

Resumen El grado mayor de proliferación de las RE células después del tratamiento de endotoxina no fué afectado por la cantidad de fósforo del régimen de alimentación pero 1.0% del fósforo abatió el thymidine incorporado dentro del DNA de la médula órea.

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Contribution from the Missouri Agricultural Experiment Station, Journal series No. 6468. Supported in part by NIH Postdoctoral Fellowship No. 1F2FR36 for R. L. Doak.     

Cell proliferation in the rat pituitary gland: a mechanism of control in prolactin cells.

We investigated the relationship between prolactin content and DNA replication in the anterior pituitary gland. Thymidine incorporation in pregnant rats is significantly lower than in virgin controls. This is accompanied by a decreased activity of DNA polymerase. Sulpiride administration to pregnant rats enhances thymidine incorporation to levels similar to virgin controls. The results indicate a negative feedback between prolactin content and DNA synthesis in the rat anterior pituitary gland.     

Effects of natural toad serum on heterologous vertebrate cells

Résumé Le sérum et le plasma, nouvellement préparés, de l'AmphibienBufo marinus, ont, in vitro, un effet rapidement cytotoxique sur des cellules normales et malignes des autres Vertébrés.