Inhibition of Fc[epsilon]RI-dependent mediator release and calcium flux from human mast cells by sialic acid-binding immunoglobulin-like lectin 8 engagement

• Published in: Journal of allergy and clinical immunology 2008-02, Vol.121 (2), p.499
• Main Authors: Yokoi, Hidenori, Choi, Oksoon H, Hubbard, Walter, Lee, Hyun-Sil, Canning, Brendan J, Lee, Hyun H, Ryu, Seung-Duk, von Gunten, Stephan, Bickel, Carol A, Hudson, Sherry A, MacGlashan, Donald W, Bochner, Bruce S
• Format: Article
• Language: English
• Subjects: Allergies; Apoptosis; Calcium; Flow cytometry; Histamine; Ligands; Medical research; Proteins; Studies
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2007.10.004

Background Sialic acid-binding immunoglobulin-like lectins (Siglecs) are a family of glycan-binding inhibitory receptors, and among them, Siglec-8 is selectively expressed on human eosinophils, basophils, and mast cells. On eosinophils, Siglec-8 engagement induces apoptosis, but its function on mast cells is unknown. Objective We sought to study the effect of Siglec-8 engagement on human mast cell survival and mediator release responses. Methods Human mast cells were generated from CD34+precursors. Apoptosis was studied by using flow cytometry. Mast cell mediator release or human lung airway smooth muscle contraction was initiated by FcεRI cross-linking with or without preincubation with Siglec-8 or control antibodies, and release of mediators was analyzed along with Ca++flux. RBL-2H3 cells transfected with normal and mutated forms of Siglec-8 were used to study how Siglec-8 engagement alters mediator release. Results Siglec-8 engagement failed to induce human mast cell apoptosis. However, preincubation with Siglec-8 mAbs significantly (P< .05) inhibited FcεRI-dependent histamine and prostaglandin D2release, Ca++flux, and anti-IgE-evoked contractions of human bronchial rings. In contrast, release of IL-8 was not inhibited. Siglec-8 ligation was also shown to inhibit β-hexosaminidase release and Ca++flux triggered through FcεRI in RBL-2H3 cells transfected with full-length human Siglec-8 but not in cells transfected with Siglec-8 containing a tyrosine to phenylalanine point mutation in the membrane-proximal immunoreceptor tyrosine-based inhibitory motif domain. Conclusion These data represent the first reported inhibitory effects of Siglec engagement on human mast cells.