Expression and subcellular localization of syntaxin 11 in human neutrophils

Syntaxin 11 mutations lead to familial hemophagocytic lymphohistiocytosis (FHL), characterized by uncontrolled hyperinflammation. This study examines the expression and subcellular localization of syntaxin 11 in human neutrophils as major inflammatory cells. The materials included human peripheral blood neutrophils, HL-60 cells. The methods used were RT-PCR, Western blot, immunocytochemistry, subcellular fractionation, HL-60 cell differentiation. We have found that human peripheral blood neutrophils express syntaxin 11 mRNA and protein. Syntaxin 11 was upregulated during neutrophil differentiation of HL-60 cells. Syntaxin 11, identified as a membrane-bound protein, was broadly located in the plasma membrane and granules, with a predominant location in azurophilic granules of resting human neutrophils. A secondary location of syntaxin 11 was in specific and tertiary granules, which resulted in translocation to the plasma membrane on cell activation conditions that promoted the release of these organelles. These data indicate that human neutrophils express syntaxin 11 and call attention to the possible involvement of neutrophils in familial hemophagocytic lymphohistiocytosis pathology.