Sialic acid–binding immunoglobulin-like lectin (Siglec) 8 in patients with eosinophilic disorders: Receptor expression and targeting using chimeric antibodies

Fanny Legrand, Yun Cao, Joshua Brian Wechsler, Xiang Zhu, Nives Zimmermann, Shakuntala Rampertaap, Joseph Monsale, Kimberly Romito, Bradford A. Youngblood, Emily C. Brock, Michelle A. Makiya, Nenad Tomasevic, Christopher Bebbington, Irina Maric, Dean D. Metcalfe, Bruce Scott Bochner, Amy D. Klion*

*Corresponding author for this work

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Background: Sialic acid–binding immunoglobulin-like lectin (Siglec) 8 is selectively expressed on eosinophils, mast cells, and basophils and, when engaged on eosinophils, can cause cell death. Objective: We sought to characterize surface and soluble Siglec-8 (sSiglec-8) levels in normal donors (NDs) and eosinophilic donors (EOs) and assess the efficacy of anti–Siglec-8 antibodies in inducing eosinophil cell death in vitro. Methods: Eosinophil expression of Siglec-8 was assessed by using flow cytometry and quantitative PCR. Serum sSiglec-8 levels were measured by means of ELISA. Induction of eosinophil death by IgG4 (chimeric 2E2 IgG4) and afucosylated IgG1 (chimeric 2E2 IgG1 [c2E2 IgG1]) anti–Siglec-8 antibodies was evaluated in vitro by using flow cytometry and in vivo in humanized mice. Results: Siglec-8 was consistently expressed on eosinophils from NDs and EOs and did not correlate with absolute eosinophil count or disease activity. sSiglec-8 levels were measurable in sera from most donors unrelated to absolute eosinophil counts or Siglec-8 surface expression. c2E2 IgG1 and chimeric 2E2 IgG4 were equally effective at inducing cell death (Annexin-V positivity) of purified eosinophils from NDs and EOs after overnight IL-5 priming. In contrast, killing of purified eosinophils without IL-5 was only seen in EOs, and natural killer cell–mediated eosinophil killing was seen only with c2E2 IgG1. Finally, treatment of humanized mice with anti-Siglec antibody led to robust depletion of IL-5–induced eosinophilia in vivo. Conclusions: Siglec-8 is highly expressed on blood eosinophils from EOs and NDs and represents a potential therapeutic target for eosinophilic disorders. Enhanced killing of eosinophils in the presence of IL-5 might lead to increased efficacy in patients with IL-5–driven eosinophilia.

Original languageEnglish (US)
Pages (from-to)2227-2237.e10
JournalJournal of Allergy and Clinical Immunology
Volume143
Issue number6
DOIs
StatePublished - Jun 2019

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Keywords

  • Siglec-8
  • apoptosis
  • eosinophil
  • eosinophilic gastrointestinal disease
  • hypereosinophilic syndrome
  • inhibitory receptor
  • mast cell
  • mastocytosis
  • monoclonal antibody
  • soluble receptor

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

Cite this

Legrand, F., Cao, Y., Wechsler, J. B., Zhu, X., Zimmermann, N., Rampertaap, S., Monsale, J., Romito, K., Youngblood, B. A., Brock, E. C., Makiya, M. A., Tomasevic, N., Bebbington, C., Maric, I., Metcalfe, D. D., Bochner, B. S., & Klion, A. D. (2019). Sialic acid–binding immunoglobulin-like lectin (Siglec) 8 in patients with eosinophilic disorders: Receptor expression and targeting using chimeric antibodies. Journal of Allergy and Clinical Immunology, 143(6), 2227-2237.e10. https://doi.org/10.1016/j.jaci.2018.10.066