Absolute selleck kinase inhibitor neutrophil
counts rapidly declined in all patients early in the course of IFN-α treatment (median drop 44%), and stabilized over the next few weeks, as previously reported4 (Fig. 1a). Monocyte numbers also significantly decreased within the first 4 weeks of treatment (Fig. 1a). However, unlike ANC, monocyte levels do not drop below the normal range (0.2–1.0 × 1000/µL) in these patients. While spontaneous G-CSF production by PBMCs was detectable in 60% (n = 26) of patients’ samples before commencing anti-viral therapy, it was detectable only in 6% (n = 3) at week 4 (Fig. 1b). In other words, PBMCs lost the ability to produce G-CSF during IFN-α treatment. The suppressed G-CSF production paralleled the drop in ANC over the course of IFN-α treatment (r = 1.0, P = 0.08). Large inter-individual variation was observed in levels of pre-treatment G-CSF secreted by patients’ PBMCs (Fig. 1b). No single clinical factor was found to correlate with these levels of G-CSF secretion (e.g. viral-load, fibrosis score). We found a similar degree
of variability in the PBMCs of healthy individuals (Fig. 1c). This suggests that some undetermined genetic or environmental factor, not associated with HCV infection contributes to the variability of G-CSF secretion. We found that PBMCs isolated from healthy controls find more or patients chronically infected with HCV secreted variable amounts of G-CSF (Fig. 1c). However, G-CSF production by PBMCs was significantly suppressed in both patients and controls (P = 0.02 and P = 0.001, respectively) upon in vitro treatment with IFN-α
(Fig. 2a,b). We consistently observed increased levels of CXCL10 produced by PBMCs in response to in vitro IFN-α treatment, excluding the possibility that the suppressed G-CSF secretion was due simply to toxicity of IFN-α (Fig. 2c,d). In addition, IFN-α or CL097, singly or in combination had no effect on cell number or viability as determined by Trypan blue or AnnexinV/PI staining (data not shown). Peripheral blood mononuclear cells and purified CD14+ 上海皓元医药股份有限公司 monocytes isolated from healthy blood donors produced high levels of G-CSF in response to in vitro stimulation with the TLR7/8 agonist, CL097 (Fig. 3a,b). The CD14- fraction of cells did not produce G-CSF (data not shown), indicating that monocytes are the main producers of G-CSF in response to this stimulus. Furthermore, TLR7/8 ligation by CL097 induced significant G-CSF secretion by PBMC and monocytes even in the presence of IFN-α (Fig. 3a). However, G-CSF levels were lower when cells were treated with both IFN-α and the TLR7/8 agonist, CL097, compared with levels when PBMCs were stimulated by CL097 alone (Fig. 3a). Interestingly, suppression of G-CSF secretion was not observed when IFN-α was added to purified CD14+ monocytes stimulated with CL097 (Fig. 3b). This indicates that IFN-α does not suppress G-CSF production by acting directly on the monocytes.