Functional platelet-activating factor receptors are expressed by monocytes and granulocytes but not by resting or activated T and B lymphocytes from normal individuals or patients with asthma

Hans Uwe Simon, Peter W. Tsao, Katherine A. Siminovitch, Gordon B. Mills, Kurt Blaser

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Platelet-activating factor (PAF) may play a role in the regulation of immune responsiveness and is a potent mediator in asthmatic inflammation. However, as yet, the mechanism whereby PAF mediates its pleiomorphic effects on immune cells have not been elucidated. Because PAF is a potent chemotactic factor for eosinophils, the presence of receptors for PAF (PAFR) on lymphocytes may provide a mechanism for the concurrent recruitment of both eosinophils and T lymphocytes into the airways of asthmatic patients. To address this issue, we have examined freshly isolated PBMC and granulocytic cells as well as various T and B lymphocyte lines with regards to PAFR expression and PAF-induced changes in intracellular calcium concentration. Using two-color immunofluorescence techniques and highly purified cell populations, it was not possible to detect surface PAFR protein or functional PAFR on resting and in vivo or in vitro activated T and B cells derived from nonallergic individuals or patients with allergic asthma. In addition, we were unable to detect PAFR mRNA, protein, or functional response to PAF in human or murine T cell lines. In contrast, we found functional PAFR in most B lymphoblastoid cell lines. Within the PBMC population, CD14+ cells respond to PAF. These results suggest that PAF does not interact directly with lymphocytes and thus that previous observations suggestive of such an interaction likely reflect the effects of PAF on monocytes. PAF-induced increases in intracellular calcium concentration were also detected in neutrophils and eosinophils, but were lower in granulocytes relative to the levels detected in monocytes.

Original languageEnglish (US)
Pages (from-to)364-377
Number of pages14
JournalJournal of Immunology
Volume153
Issue number1
StatePublished - Jul 1 1994
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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