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Biochem J. 1993 Aug 1;293 ( Pt 3):835-42.

Signalling through CD28 T-cell activation pathway involves an inositol phospholipid-specific phospholipase C activity.

Author information

1
Unité de Cancérologie et Thérapeutique Expérimentales U 119 INSERM, Marseille, France.

Abstract

Stimulation of the human T-cell line, Jurkat, by a monoclonal antibody (mAb) directed against the CD28 molecule leads to sustained increases in intracellular levels of Ca2+ ([Ca2+]i); the initial rise in Ca2+ comes from internal stores, followed by Ca2+ entry into the cells. The CD28 molecule also appears to activate polyphosphoinositide (InsPL)-specific phospholipase C (PLC) activity in Jurkat cells, as demonstrated by PtdInsP2 breakdown, InsP3 and 1,2-diacylglycerol generation and PtdIns resynthesis. We also observed that interleukin-2 (IL2) production induced via CD28 triggering was sensitive to a selective protein kinase C inhibitor. Of the four other anti-CD28 mAbs (CD28.2, CD28.4, CD28.5, CD28.6) tested, only one (CD28.5) was unable to generate any InsPL-specific PLC or IL2 secretion. However, the cross-linking of cell-bound CD28.5 with anti-mouse Ig antibodies led to an increase in [Ca2+]i. CD28-molecule clustering in itself appears to be a sufficient signal for induction of PLC activity.

PMID:
8394695
PMCID:
PMC1134444
DOI:
10.1042/bj2930835
[Indexed for MEDLINE]
Free PMC Article

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