The identification of neutrophil adhesion in the pulmonary microcirculation as the major driver of hypoperfusion suggests that Syk inhibitors with low effects on platelets and thrombosis in vivo, such as R406 (the active metabolite of Fostamatinib),61 could be effective and safe to improve ACS in SCD; however, their efficacy remains to be determined. Here, SYK is linked to acute chest syndrome.