PPD-induced blastogenesis is auto-regulated by suppressor cells generated in vitro.

Suppressor cell induction can be demonstrated during antigen specific blastogenesis by using the same methods which have shown induction of suppressor cells by Con A. Since suppressor cells are rapidly generated during antigen specific blastogenesis, they must regulate the final level of blastogenesis induced during the seven day in vitro incubation.     

Antiandrogenic suppression of lymphocytic blastogenesis: in vitro and in vivo observations

Zusammenfassung Nachweis, dass die Fähigkeit zur Blastogenese der Lymphozyten gesunder junger Männer nach Reizung mit Phytohämagglutinin im peripheren Blut unterdrückt wird, wenn die Lymphozyten zusammen mit östrogen (Diethylstilbestrol-Diphosphat) kultiviert werden.     

Suppression of PHA-induced lymphocyte blastogenesis by concomitant presence of PPD in the culture

Summary PHA-induced lymphocyte blastogenic response was remarkably suppressed by the simultaneous presence of PPD in cultures of lymphocytes derived from individuals sensitized to PPD, but not affected by the presence of PPD when the cultures contained lymphocytes from an individual not sensitized to the protein. This double stimulation blastogenesis study with PHA and a specific antigen is feasible as a simple and rapid test to measure cell-mediated immunity to the antigen.Supported by United States grant USPHS Grant AM 27384.     

Immune suppression by neutrophils and granulocytic myeloid-derived suppressor cells: similarities and differences

Neutrophils are essential effector cells in the host defense against invading pathogens. Recently, novel neutrophil functions have emerged in addition to their classical anti-microbial role. One of these functions is the suppression of T cell responses. In this respect, neutrophils share similarities with granulocytic myeloid-derived suppressor cells (G-MDSCs). In this review, we will discuss the similarities and differences between neutrophils and G-MDSCs. Various types of G-MDSCs have been described, ranging from immature to mature cells shaping the immune response by different immune suppressive mechanisms. However, all types of G-MDSCs share distinct features of neutrophils, such as surface markers and morphology. We propose that G-MDSCs are heterogeneous and represent novel phenotypes of neutrophils, capable of suppressing the immune response. In this review, we will attempt to clarify the differences and similarities between neutrophils and G-MDSCs and attempt to facilitate further research.     

Stimulation of growth by insulin inDrosophila embryonic cells in vitro

Summary For obtaining a better yield of established lines of embryonicDrosophila cells, insulin proved to be a useful substance to be added to the culture medium. 10% of lines became established, showing a predominatly diploid chromosome number.     

Differentiation of neuroblastoma cells induced by nerve growth factor in vitro

Zusammenfassung Durch Züchtung in vitro wird gezeigt, dass Zellen eines menschlichen Neuroblastoms unter dem Einfluss eines Nervenwachstumsfaktors die Fähigkeit haben, sich in Nervenzellen zu differenzieren und somit die Zellen dieses bösartigen Tumors histogenetische Potenzen besitzen, welche nicht aktiviert werden.     

Enhanced inhibition of RNA synthesis by amanitins in in vitro cultured cells

Summary The inhibition of RNA synthesis by -amanitin on vitro cultured cells is very slow. The action of various analogues of the toxin was tested and some of them proved more effective. Moreover pretreatment of cell cultures with DEAE-dextran greatly enhanced the effect of -amanitin.Acknowledgments. We thank ProfessorTh. Wieland and Dr.H. Faulstich (Max-Planck-Institut, Heidelberg) for the generous gift of amanitins. This investigation was supported by grant No. 74.00637.65 from C.N.R. (Roma).     

Nicotinamide is an inhibitor of SIRT1 in vitro,but can be a stimulator in cells

Nicotinamide (NAM), a form of vitamin B₃, plays essential roles in cell physiology through facilitating NAD⁺ redox homeostasis and providing NAD⁺ as a substrate to a class of enzymes that catalyze non-redox reactions. These non-redox enzymes include the sirtuin family proteins which deacetylate target proteins while cleaving NAD⁺ to yield NAM. Since the finding that NAM exerts feedback inhibition to the sirtuin reactions, NAM has been widely used as an inhibitor in the studies where SIRT1, a key member of sirtuins, may have a role in certain cell physiology. However, once administered to cells, NAM is rapidly converted to NAD⁺ and, therefore, the cellular concentration of NAM decreases rapidly while that of NAD⁺ increases. The result would be an inhibition of SIRT1 for a limited duration, followed by an increase in the activity. This possibility raises a concern on the validity of the interpretation of the results in the studies that use NAM as a SIRT1 inhibitor. To understand better the effects of cellular administration of NAM, we reviewed published literature in which treatment with NAM was used to inhibit SIRT1 and found that the expected inhibitory effect of NAM was either unreliable or muted in many cases. In addition, studies demonstrated NAM administration stimulates SIRT1 activity and improves the functions of cells and organs. To determine if NAM administration can generate conditions in cells and tissues that are stimulatory to SIRT1, the changes in the cellular levels of NAM and NAD⁺ reported in the literature were examined and the factors that are involved in the availability of NAD⁺ to SIRT1 were evaluated. We conclude that NAM treatment can hypothetically be stimulatory to SIRT1.     

Inhibition of lymphocyte blastogenesis by diazepam, meprobamate, and other psychotropic drugs]

Imipramine, diazepam, chlordiazepoxide, and meprobamate inhibit incorporation of 3H-thymidine in human lymphocytes in culture. For the first three drugs, 50% inhibition occurs at a concentration of 5 X 10(-5) M, and for meprobamate at a concentration of 10(-3 M. Ethanol has no action up to 10(-1) M.     

The uptake of iodinated protein by spleen cells of guinea-pigs in vitro

Zusammenfassung 6×10^–10 g bis 10^–4 g J 125 Rinderserum-Albumin (BSA) bzw. 1,0×10^–7 bis 1,0×10^–6 g J 125 Rinderserum--Globulin (BGG) werden 3 × 10⁷ Milzzellen normaler Meerschweinchen in vitro angeboten. Unabhängig von der Höhe des Angebotes beträgt die Menge des aufgenommenen BSA 1%, die des aufgenommenen BGG 10% des Angebotes. Durch 4C Inkubations-temperatur wird die Aufnahme z.T. behindert. Die Aufnahme findet nach wenigen Sekunden Inkubationszeit statt und ist nach etwa 2–3 min abgeschlossen.

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The work was supported by a grant of the Stiftung Volkswagenwerk and of the Deutsche Forschungsgemeinschaft.     

Histamine release by passive sensitization with murine neoplastic mast cells in vitro

Riassunto Mastociti neoplastici di un clono diploide, coltivati nel topo come tumore-ascite, sono stati impiegati per produrre nel coniglio un antisiero specifico verso celiule dello stesso clono. L'incubazione con l'antisiero produce liberazione di istamina da parte di mastociti dello stesso clono; l'effetto non si osserva se i mastociti sono incubati con sieri ottenuti dagli stessi animali prima della sensibilizzazione. Viene prospettato 1'uso di questo modello sperimentale per sue possibili applicazioni allo studio iella liberazione dell'istamina nella sensibilizzazione passiva dei mastociti.

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The present investigation has been aided by grant NB 00940 from the National Institute of Neurological Diseases and Blindness. The experiments have been performed during one year's tenure of a N.A.T.O. Fellowship at the Department of Pharmacology, Yale University, New Haven, Connecticut.