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Activation and up-regulation of phospholipase D expression by lipopolysaccharide in human peripheral T cells.

Authors
  • Chien, Eileen Jea
  • Chen, Chien-Ching
  • Chien, Chau-Heng
  • Yeh, Tzu-Pei
  • Lu, Li-Ming
Type
Published Article
Journal
The Chinese journal of physiology
Publication Date
Dec 31, 2004
Volume
47
Issue
4
Pages
203–209
Identifiers
PMID: 15803754
Source
Medline
License
Unknown

Abstract

In a previous study, we showed that bacterial LPS activates protein kinase C (PKC) and causes an intracellular pH (pHi) increase, but does not elevate intracellular calcium ([Ca2+]i) in human peripherial T cells. Hence this study aimed to investigate whether the activation of PKC was resulted from phospholipase D (PLD) catalysis by LPS. The activity of PLD was measured by the production of 3H-phosphatidylethanol from phosphatidic acid (PA), and the expression of PLD or IL-2 Ralpha was determined by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Enzyme-linked immunosorbent assay (ELISA) was used to analyze IL-2 and IL-4. Phytohemagglutinin (PHA), and phorbol 12-myristate 13-acetate (PMA) were used as controls. Our results indicated that (1) LPS-stimulated pHi elevation was PKC dependent; (2) After 30 min stimulation, LPS increased PLD activity via a measured production of 3H-phosphatidylethanol from phosphatidic acid and the initiation of PLD1a mRNA expression started; (2) LPS stimulated IL-2 R expression but not IL-2 and IL-4 secretion. Our findings suggested that the stimulation of PLD activity and its mRNA expression by LPS might be required for IL-2 R expression and a sustained PKC dependent pHi elevation but not for the secretion of IL-2 or IL-4 in human T cells. This indicated that LPS might enhance T cell adaptive immunity to resist Gram-negative bacterial infection.

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