Lipid droplet occurrence in human leukocytes of peripheral blood is higher in males with recent-onset psychosis

Aberrant immune mechanisms in central and peripheral nervous system might underlie the heterogeneity of symptoms in schizophrenia. Lipid droplets (LDs) are implicated in inflammatory processes and immune response. Previous studies have successfully quantified LDs in cell lines by Nile Red staining. Therefore, we hypothesized that LD abundance could be optimally quantified in leukocyte subpopulations and that LD occurrence in peripheral blood leukocytes could be altered in people with psychosis at early stages of the disorder. We optimized a method to detect and quantify LD occurrence in different leukocyte subpopulations using flow cytometry. We found that leukocyte subpopulations contain LDs, with lymphocytes showing the lowest LD content, followed by monocytes, neutrophils and eosinophils. Leukocytes were able to modulate their LD abundance upon oleate exposure in in vitro blood culture from controls. Moreover, LD content was significantly higher in all leukocyte subpopulations in recent-onset psychosis (ROP) compared to controls. When stratified by sex, these differences were maintained in males but not in females. Leukocyte subpopulations from males with ROP contain higher LD levels than controls, suggesting LD abundance as a potential male biomarker of a pro-inflammatory stage early in the disorder course. Further studies are required to confirm these findings in females.