Release of adenosine from human neutrophils stimulated by platelet activating factor, leukotriene B₄ and opsonized zymosan

Abstract

Isolated human polymorphonuclear leukocytes (PMNL) stimulated by platelet activating factor (PAF), leukotriene B₄ (LTB₄) or opsonized zymosan (OZ) released adenosine measured by thermospray high performance liquid chromatography mass spectrometry in the cell-free supernatants. Stimulation by PAF or LTB₄ resulted in a bellshaped concentration-effect curve; 5 × 10⁻⁷ M PAF, 10⁻⁸ M LTB₄ and 500 μg ml⁻¹ OZ induced peak adenosine release, thus cytotoxic concentrations did not elevate adenosine level in the supernatants. Therefore adenosine release was characteristic of viable cells. As calculated from concentration-effect curves, the rank order of potency for adenosine release was PAF > LTB > OZ. These resuits suggest that adenosine, when bound specifically to membrane receptor sites, may initiate signal transduction, and, in co-operation with other inflammatory mediators, may modulate phagocyte function, e.g. production of chemoluminescence (CL).