Methods: LAD2 human mast cells [1], primary human basophils, and THP-1 human myeloid cells were used for investigations of FcεRI and Toll-like receptor (TLR) ligand-induced responses. Quantitative real-time PCR, Western blot analysis, ELISA, fluorometry, luminometry and fluorescence microscopy were used to run the assays.
Results: In contrast to basophils, LAD2 mast cells expressed high background levels of HIF-1α, which was largely independent of the effects of stem cell factor (SCF) [2]. Both mast cells and basophils expressed TLR2 and 4, albeit weakly compared to THP-1 cells. Cytokine production in mast cells following TLR ligand stimulation was markedly reduced by HIF-1α knockdown in LAD2 mast cells. In contrast, although HIF-1 is involved in IgE-mediated IL-4 secretion from basophils, it was not clearly induced by the TLR2 ligand PGN.
Conclusions: HIF-1α accumulation is fundamentally important for sustaining human allergic effector cell survival and function. This transcription complex facilitates the generation of both pro-angiogenic and inflammatory cytokines in mast cells but has a differential role in basophil stimulation comparing IgE-dependent triggering with innate immune stimuli.
References:
- Kirshenbaum AS, Akin C, Wu Y, Rottem M, Goff JP, Beaven MA, et al. (2003) Leuk Res; 27:677-82.
- Gibbs, BF, Yasinska, IM, Oniku, AE, Sumbayev, VV (2011) PLoS One; in press.