Surface expression of MRGPRX2 on resting basophils: An area of controversy

Reply to Sabato V et al “Surface expression of MRGPRX2 expression on resting basophils: An area of controversy”

“…It was surprising that Sabato et al 1 found similar MRGPRX2 expression of unstimulated basophils of birch pollen allergics and of anti-IgE stimulated controls (median 4, range 0-14, Table 1). Having analyzed a huge variety of stimuli (unpublished), among the few substances, we identified as inducers of basophil MRGPRX2 surface expression there were two, namely anti-IgE and fMLP, that were also described by Sabato et al 1 Re-analyzing our BAT data of grass-pollen allergic subjects regarding CD63 and MRGPRX2 expression, we found that there was a significant correlation in anti-FcεRI stimulated basophils, but not in basophils stimulated with medium or fMLP (Figure 3). This confirms on the one hand that our basophils were not activated by the isolation method or the medium control and that activation of the cells, that is, by stimulation with fMLP, did not always result in MRGPRX2 upregulation.…”

“…Secondly, in their correspondence Sabato et al criticize that we have not mentioned their postulation about the potential of basophil activation experiments in immediate hypersensitivity reactions originating from MRGPRX2 occupancy by quinolones. 1,4 We appreciate this comment on their data demonstrating that hypersensitivity to moxiflocacin is difficult to capture by traditional CD63/CD203c-based basophil activation test. 4 Nevertheless, in their study, they explored whether simultaneous quantification of alterations of CD63/CD203c surface expression and changes of the intracellular histamine content at a single-cell level could help to disentangle the effect of moxiflocacin on basophils.…”

“…We thank Sabato et al for pointing to their prior published results demonstrating MRGPRX2 expression on human basophils 1,2 . We apologize that we have overlooked their work that was published as an abstract and therefore not found in PubMed.…”

“…We apologize that we have overlooked their work that was published as an abstract and therefore not found in PubMed. In their abstract, Sabato et al 1 describe intracellular MRGPRX2 expression to occur in all basophils, but constitutive surface expression to occur in only a minority of basophils. We respectfully disagree with Sabato et al's 1 suggestion that our basophils were primed related to the medium we used.…”

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To the Editor, We thank Sabato et al for pointing to their prior published results demonstrating MRGPRX2 expression on human basophils. 1,2 We apologize that we have overlooked their work that was published as an abstract and therefore not found in PubMed. In their abstract, Sabato et al 1 describe intracellular MRGPRX2 expression to occur in all basophils, but constitutive surface expression to occur in only a minority of basophils.

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