Sexual dimorphism in neutrophil function: Unveiling the discriminative nature of male and female neutrophils

Abstract

Background: Women and men are different on many biological levels. Mounting evidence is now recognized that even the immune system has some significant sex differences, which are mainly cell mediated. This study investigated sex-specific differences in function and regulation of polymorphonuclear neutrophil granulocytes (PMNs) in male and female healthy human donors to gain a deeper understanding of the immune response and potential sex-specific dimorphism in immunology.

Methods: PMNs were obtained from whole blood samples of healthy female and male donors by leuko-/lymphospin density centrifugation. Chemotaxis assays using μ-slide chemotaxis chambers were performed, in which N-formylmethionin-leucyl-phenylalanine (fMLP) stimulated PMNs migrated through a type I collagen matrix. We measured the production of reactive oxygen species (ROS), the release of myeloperoxidase (MPO), and the formation of Neutrophil Extracellular Traps (NETs). Additionally, a flow cytometry assay was conducted to examine functional variations of neutrophil surface markers CD62L, CD11b, and CD66b, as well as the oxidative burst in PMNs obtained from male and female donors.

Results: Sex specific differences of neutrophil function could be determined. Male-derived PMNs initially migrated further distances, while female-derived PMNs showed more targeted movement. However, as the observation period progressed, male-derived PMNs began to exhibit more targeted migration, maintaining straightness towards the end. Differences in neutrophil surface marker expression were observed, with greater levels of CD11b and CD66b on male-derived PMNs after 2 h resting. The different immune effects between the sexes were seen in live cell imaging as well as in flow cytometry analyses.

Conclusion: The study revealed significant functional differences between PMNs from male and female donors. To gain reliable results in future PMN studies, it is crucial to consider the sex of the donor.

Keywords: Chemotaxis; Epitopes; Neutrophil function; Sex; Sexual dimorphism.