Changes in the plasma membrane surface of lymphocytes stimulated in vivo with DNCB

Summary Stereological principles have been used to evaluate ultrastructural changes which accompany the transformation of lymphocytes stimulated in vivo with dinitrochlorobenzene (DNCB). Whereas unstimulated lymphocytes and blast cells have slightly more than the minimal containing plasmalemmal surface for their volume, stimulated (blast-derived) lymphocytes have an excess surface area in the order of 30%. This observation is discussed in the context of altered cell function and the biosynthesis of additional membrane components.We wish to thank Prof. R. Barer for his continued support and encouragement. The work was undertaken by M.M. A.-H. in part fulfilment of requirements for the degree of Ph. D. in this department. M.M. A-H. was supported by the Ministry of Higher Education and Scientific Research, Government of Iraq.     

Cytotoxic potential of lymphocytes stimulated with autochthonous lymphoid cell line cells

Résumé Les petits lymphocytes du sang, après avoir été mis en contact pendant plusieurs jours avec les cellules lymphoïdes d'une lignée autochthone, peuvent tuer les cellules de cette lignée et d'autres lignées. Ces investigations peuvent apporter de nouvelles données sur l'opération de contrôle immunologique.

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We are grateful to Dr.N. R. Ling for his help and guidance.D. A. Hardy gratefully acknowledges financial support from the Medical Research Council and the John Squire Fund.     

Cytophotometric studies of the course of the S phase in PHA stimulated lymphocytes

Zusammenfassung Karyologische und zytophotometrische Untersuchungen an PHA-stimulierten menschlichen Lymphozyten ergaben nach 76 h im DNS-Karyogramm einen weiteren Gipfel zwischen diploiden und tetraploiden Werten. Daraus wird geschlossen, dass bei Lymphozyten in der Kultur die DNS-Synthese in der S-Phase diskontinuierlich verläuft.     

Studies on human lymphocytes stimulated in vitro with anti-γ and anti-μ antibodies

Zusammenfassung Es konnte gezeigt werden, dass sich menschliche periphere Lymphozyten, mit Antikörper gegen die H-Ketten des-Globulins behandelt, in Lymphoblasten umwandeln lassen und dass sie in vitro DNA synthetisieren.     

Suppression of DNA synthesis in phytohaemagglutinin stimulated lymphocytes by prednisone treatment

Résumé Recherches autoradiographiques faites sur des cultures de sang périphérique de deux enfants leucémiques, l'un traité et l'autre non traité au prednisone. Un abaissement significatif de la synthèse DNA s'est produit après 68 h dans la culture du cas traité.     

The environment in which lymphocytes differentiate influences their ability to cooperate in vivo.

Whether or not parental B lymphocytes cooperate with F1 T lymphocytes depends upon the environment in which parental bone marrow cells differentiate. Only those parental B lymphocytes that have differentiated in the F1 environment are able to cooperate with F1 T lymphocytes.     

Changes in erythrocyte membrane lipid composition affect the transient decrease in membrane order which accompanies insulin receptor down-regulation.

We have recently demonstrated, using electron paramagnetic resonance (EPR) spectroscopy, that insulin receptor internalization in response to insulin incubation (down-regulation) in human erythrocytes is accompanied by a transient decrease in membrane order, as measured by the 2T' parallel order parameter. Since membrane lipids play such an important role in receptor internalization, we investigated the possible effects that an alteration of the normally-occurring lipid profile might have on down-regulation and the concomitant transient decrease in membrane order. Consequently, human erythrocytes enriched with cholesterol and erythrocytes from cirrhotic patients were examined, because both of these groups of cells have a higher cholesterol/phospholipid molar ratio (CH/PL) than controls. The 5-nitroxystearate spin label, which inserts into the lipid bilayer of cell membranes, was used to monitor changes in 2T' parallel for a 3-h period at 37 degrees C. We report here that both cholesterol-enriched and cirrhotic erythrocytes do not down-regulate, as demonstrated by binding assays, and that they do not show the typical transient decrease in membrane order observed in controls. The results seem to indicate that a more ordered membrane inhibits internalization of the insulin receptor in erythrocytes, and that an increase in membrane disorder is necessary for insulin receptor down-regulation.     

Effect of methotrexate on DNA synthesis and thymidine kinase activity of human lymphocytes stimulated with phytohaemagglutinin

Riassunto Il methotrexate provoca nei linfociti umani stimolati per 48 con fitoemagglutinina un aumento di incorporazione di timidina³H nell'ADN senza modificare sensibilmente il numero di cellule in fase S. La sintesi di ADN valutata con l'incorporazione di³²P risulta diminuita, mentre l'attività della timidin kinasi non è modificata dal trattamento con MTX.

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This work was supported by Consiglio Nazionale delle Ricerche (CNR), Rome.     

Olfactory receptor trafficking to the plasma membrane

Olfactory receptors typically exhibit poor plasma membrane localization and functionality when heterologously expressed in most cell types. It has therefore proven difficult to effectively study olfactory receptor pharmacology and signaling mechanisms using traditional cell culture systems. Over the past few years, a variety of distinct proteins have been reported to interact with olfactory receptors and facilitate olfactory receptor trafficking to the plasma membrane in heterologous cells. Advances in this area have shed significant light on the fundamental factors governing the cell-specific control of olfactory receptor trafficking.