Decreased expression of CD200R3 on mouse basophils as a novel marker for IgG1‐mediated anaphylaxis

Abstract

IgE-mediated mast cell activation is the trigger of anaphylaxis in humans, whereas it is known that not only IgE but also IgG can induce anaphylaxis in mice. In our preliminary experiments, the expression of a murine basophil identification marker, CD200R3, on antigen-sensitized basophils decreased following specific antigen challenge. Interestingly, this decrease did not always correspond with increased expression of the IgE-mediated basophil activation marker CD200R1. Since IgG as well as IgE plays a role in mouse anaphylaxis, we hypothesized that the observed decrease in CD200R3 on basophils was caused by IgG-mediated cell activation. We attempted to establish whether CD200R3 is a marker of IgG-mediated basophil activation and if its expression is correlated with anaphylaxis in a mouse model. Mouse basophils were stimulated via Fc∊Rs and/or FcγRs, and levels of CD200R1 and CD200R3 were analyzed by flow cytometry. Basophils derived from naive mice were challenged with a natural antigen, β-lactoglobulin, after passive sensitization with anti-β-LG serum or IgG/IgG subclass-depleted antiserum. Systemic anaphylaxis was induced by i.v. injection of anti-FcγRIII/II monoclonal antibody, and CD200R3 expression on peripheral basophils was assessed. Stimulation via Fc∊Rs induced a significant increase in CD200R1 expression but had only a small effect on that of CD200R3. However, anti-FcγRIII/II stimulation reduced CD200R3 expression markedly. In passive sensitization experiments, down-regulation of CD200R3 induced by antigen challenge was strongly negated by the depletion of IgG or IgG1 from antiserum. Intravenous injection of anti-FcγRIII/II induced CD200R3 down-regulation on peripheral basophils, together with a drop in rectal temperature. Lowered CD200R3 expression on basophils is induced by IgG-mediated stimulation via FcγRs. Use of CD200R1 and CD200R3 as activation markers enables the evaluation of murine basophil activation mediated by IgE and IgG, respectively.

Monovalent Fc receptor blockade by an anti–Fcγ receptor/albumin fusion protein ameliorates murine ITP with abrogated toxicity

“…Basophils are known to be pivotal for IgG-induced anaphylaxis, 38 and the basophilic surface receptor CD200R3 has recently been demonstrated to be a marker for anti-FcgR antibody-mediated anaphylaxis. 13,38 We confirmed the finding that the 2.4G2-mediated anaphylactic response significantly lowered CD200R3 levels on basophils, an effect absent in response to 2.4G2 scFv-MSA treatment. In addition to the decreased CD200R3 level, we observed a transient basophil depletion in response to 2.4G2 treatment, but not 2.4G2 scFv-MSA.…”

“…A recent report demonstrated that 2.4G2-induced anaphylaxis significantly reduced basophil expression of CD200R3, an activating cell surface receptor. 13 CD200R3 was expressed on basophils ( Figure 5A-B). The administration of 0.43 nmol (65 mg) 2.4G2 rapidly reduced the ability to detect CD200R3 on basophils, which partially recovered after 24 hours ( Figure 5C).…”

“…6 Such coordinated cross-linking, normally mediated by the Fc region of immunoglobulin (Ig) G-opsonized immune complexes, represents an important mode of immune activation. 6 However, uncontrolled cross-linking of FcgRs, such as by an anti-FcgRIIIA antibody, can lead to an anaphylactic reaction, 6,12,13 as evidenced by the 3G8 trial. 8,10 One potential means of reducing unwanted adverse events involves abolishing Fc-mediated effector function.…”

“…13,21 Briefly, mice were bled before treatment and 4 and 24 hours after treatment. Red blood cells (RBCs) were lysed by incubation with ammonium chloride buffer for 5 minutes at 37°C, and the peripheral blood mononuclear cells (PBMCs) were then stained with anti-CD49b-Pacific Blue (DX5), anti-FceRIa-PerCP/Cy5.5 (MAR-1) (both from Biolegend), and anti-CD200R3-FITC (BA103) (Hycult Biotech, the Netherlands).…”

“…12,13 Briefly, mice were injected intravenously with 0.43 nmol (65 mg) 2.4G2 or equimolar amount of 2.4G2 scFv-MSA or HSA. To cross-link 2.4G2 scFv-MSA before in vivo administration, a half-molar amount (0.22 nmol) of anti-His antibody was added to 0.43 nmol 2.4G2 scFv-MSA and incubated for 30 minutes at room temperature.…”