Revisit the Inhibitory Effects of Glucocorticoids on Immunocytes

Glucocorticoids (GCs) are efficacious agents for reducing inflammation and suppressing immune responses, exerting various effects on immune cells through the intracellular glucocorticoid receptor (GR), and impacting both innate and adaptive immunity. In the context of COVID-19, glucocorticoids are often used to treat severe cases of patients by reducing inflammation, suppressing immune responses, and ameliorating the severity of COVID-19. However, the precise inhibitory effects on immune cells have yet to be comprehensively delineated. In this study, we extensively examined the inhibitory effects of treating Balb/c mice with dexamethasone (DEX) on lymphoid and myeloid cells. We observed that high doses of DEX treatment resulted in a reduction in the number of immunocytes and an attenuation of their activity. Particularly noteworthy, macrophages, DC cells, and monocytes were diminished by approximately 90% following high doses of DEX, while B cells experienced a reduction of about 70% and CD3 T cells were less affected. Furthermore, our findings demonstrated that DEX induces the inhibition of immune cells by engaging in high-affinity binding to GR. Consequently, we conclude that DEX treatments affect a broad range of immune cells, encompassing both lymphoid and myeloid cells, through depletion or the down-regulation of immune function, potentially acting via the GR signaling pathway. These findings may enhance the clinical applicability of DEX in achieving transient immune deficiency.