Fig. 1

The evolution of neutrophils in humans. In humans, neutrophils originate from GMPs residing within the bone marrow, which are characterized by the expression of CD34, CD38, and CD45RA [29, 30]. Subsequently, these GMPs differentiate into pro-neutrophils (pro-neutrophil 1 and pro-neutrophil 2) and pre-neutrophils, expressing biomarkers such as CD11b, CD66b, and CD15 [31, 32]. This specific stage of neutrophil development, characterized by the presence of immature neutrophils exhibiting relatively high levels of biomarkers such as CD11b, CD16b, CD71, and CD117, has been duly acknowledged [26, 31, 33]. Ultimately, neutrophils that express chemokine receptors (CXCR)4 and CXCR2 undergo final maturation and are subsequently released into circulation. The C-X-C Motif Chemokine Ligand (CXCL)12 expressed by bone marrow stromal cells activates the neutrophil receptor CXCR4 to retain it within the bone marrow. While under the stimulation of G-CSF, endothelial cells in the bone marrow upregulate CXCL2 expression to activate CXCR2 signaling, thereby facilitating the releasing of neutrophils from the bone marrow into circulation [34, 35, 36]. Conversely, under pathological circumstances, the presence of mature neutrophils exhibiting abnormal biomarkers or immature neutrophils within the peripheral blood of humans has been reported [37, 35, 38]