T-lymphocyte function from peripheral blood stem-cell donors is inhibited by activated granulocytes

Identification of discrete tumor-induced myeloid-derived suppressor cell subpopulations with distinct T cell–suppressive activity

“…Up to now, such a low-density phenotype has been reported mainly for human granulocytes upon G-CSF treatment or fMLP activation and in patients confronted with overwhelming inflammation or cancer. [39][40][41] While in naive mice CD11b ϩ Ly6C ϩ Ly6G Ϫ splenocytes consisted mainly of monocytes and eosinophils; the latter did not expand in tumor-bearers. Furthermore, the phenotype of tumorinduced monocytes was not identical to that of their naive counterparts, expressing higher levels of CD71, CD115, and CD80.…”

Social networking of human neutrophils within the immune system

“…24,25 LDNs described in sepsis seem to be mostly immature and functionally poorly characterized ( Figure 1A). 20 LDNs isolated from patients suffering from autoimmune diseases, such as systemic lupus erythematosus (SLE) and psoriasis, have been instead more recently defined as low-density granulocytes (LDGs) ( Figure 1A) and mostly consist of a mixed population of immature and mature cells with neutrophil-like morphology.…”

“…10,19,21,24,25 Confusion still exists regarding the phenotype of G-MDSCs, with some reports describing these cells as activated, whereas others describe them as immature cells with neutrophil-like morphology. 10 The immunosuppressive function exerted by G-MDSCs is mainly defined according to their ability to suppress T-cell activation/proliferation, and it has been shown to be primarily mediated by overproduction of arginase 1 and/or reactive oxygen species (ROS).…”

G-CSF-treated granulocytes inhibit acute graft-versus-host disease

“…26 PBMCs purified from healthy persons on Ficoll-Hypaque density gradient is composed primarily of lymphocytes and a small number of monocytes. However, low-density cells from the peripheral blood of G-CSF-treated donors carry high numbers of low-density granulocytes (LDGs) that copurify with the mononuclear cell fraction.…”

“…These LDGs inhibit the production of IL-4 and IFN-␥ by CD3 ϩ cells measured ex vivo by flow cytometry. 24,26 LDGs are short lived. After 48 hours in culture, they undergo apoptosis, and T-cell IFN-␥ production is reverted.…”