Mechanisms of Allergy
Cysteinyl leukotrienes induce IL-4 release from cord blood–derived human eosinophils,☆☆

https://doi.org/10.1067/mai.2002.124269Get rights and content

Abstract

Background: Eosinophils contain preformed stores of IL-4 within their cytoplasmic granules, but physiologic stimuli to release IL-4 from eosinophils are not yet defined. Objective: We evaluated whether cysteinyl leukotrienes (CysLTs) could elicit IL-4 release from eosinophils. Methods: We used a dual-antibody capture and detection assay (EliCell) for IL-4 release and used eosinophils differentiated in vitro from human cord blood-derived progenitors. Results: Leukotriene (LT) C4, LTD4, and LTE4 each elicited the rapid, vesicular transport-mediated, dose- and time-dependent release of IL-4 from eosinophils. Both LTD4 and LTE4 evoked similar and earlier IL-4 release than LTC4. LTC4 did not act directly but only after conversion to LTD4 because an inhibitor of γ-glutamyl transpeptidase, acivicin, blocked LTC4-induced IL-4 release. MK571 and LY171833, receptor antagonists for CysLT1 and not CysLT2, and pertussis toxin inhibited LTC4-, LTD4-, and LTE4-induced IL-4 release. Cord blood-differentiated eosinophils contained CysLT1 protein detectable by means of immunoblotting. Conclusion: CysLTs acting through Gi protein-coupled and MK571- and LY171833-inhibitable receptors on cord blood-derived human eosinophils can act as autocrine or paracrine mediators to stimulate the rapid, nonexocytotic release of preformed IL-4. (J Allergy Clin Immunol 2002;109:975-9.)

Section snippets

In vitro derivation of eosinophils

Eosinophils were differentiated in vitro from human placental cord blood-derived progenitors, as previously described.10 Briefly, mononuclear-enriched cells were cultured on a 1-mm layer of Matrigel (Becton-Dickinson) in supplemented RPMI-1640 medium containing 350 pmol/L rhIL-3 and 200 pmol/L rhIL-5 (Peprotech). Nonadherent cells were passed weekly. Complete eosinophil differentiation was ascertained by means of morphologic analysis of Wright- and Giemsa-stained cells. As previously defined,10

Results

We used human eosinophils derived in vitro from IL-3- and IL-5-stimulated cord blood progenitors to evaluate whether CysLTs might function as autocrine-paracrine activators to elicit IL-4 release from eosinophils. As previously described,10, 12, 13 at week 4 of incubation with IL-3/IL-5 in a Matrigel bed, virtually all progenitor cells developed from mononuclear cells into mature eosinophils. These in vitro-derived eosinophils contain eosinophilic granules and mRNA transcripts for

Discussion

The capacity of eosinophils to release their granule-stored IL-4 by means of a regulated, nonexocytotic process of vesicular transport would enable this TH2 cytokine to be rapidly secreted in the tissue environments around appropriately activated eosinophils. To date, the CC chemokines eotaxin and RANTES are the only physiologic stimuli recognized to elicit the vesicular transport-mediated release of preformed IL-4 from eosinophils.9 Prior studies had identified nonphysiologic stimuli, such as

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  • Cited by (0)

    Supported by National Institutes of Health grants AI20241, AI22571, AI41995, and HL56386.

    ☆☆

    Reprint requests: Peter F. Weller, MD, Beth Israel Deaconess Medical Center, DA-617, 330 Brookline Ave, Boston, MA 02215.

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