It is interesting that the highest effect of RSV persistence was the increase in FcRIIB, an inhibitory receptor, and yet phagocytosis is higher in M?Ps cells. of immune responses and immune system homeostasis [12,13]. RSV, a paramyxovirus of the genus 0.05); (B) Expression of FcRIIB/RIII in the above mentioned passages of M?N or M?P cells. Cell-membrane FcRIIB/RIII were stained with specific monoclonal antibody 2.4G2 and secondary FITC-labeled F(ab’)2 fragments of anti-rat antibodies, and analyzed by flow cytometry. Each individual bar represents the MFI of 10,000 cells. Statistical analysis of the average of the three different passages of M?N and M?P (38.67 2.4 = 0.016). 2.1.2. Increase in FcRIIB/RIII Cell Membrane Expression Is Not Mediated by Soluble Factors Persistence of RSV in macrophages could induce the release of extracellular factors (e.g., cytokines, viral particles, viral products), which would act in a paracrine-like way in order to induce the increase in FcRIIB/RIII expression. Seeking to investigate whether the increased expression of FcRIIB/RIII was produced by factors released by persistently infected M?P, we treated M?N cells with a conditioned medium obtained from M?N or M?P cultures after an incubation period of 12 h or 24 h. Expression levels of FcRIIB/RIII were determined by flow cytometry. Mean fluorescence intensity (MFI) of FcRIIB/RIII expression by M?N was not significantly altered when M?N were incubated for 24 h with supernatants from M?N or M?P (Figure 3). So as to Letermovir verify that M?N are able to increase the expression of FcRIIB/III in response to a stimulus already known to increase the expression of these receptors , M?N were incubated with heat-killed NHTi, which induced a significant increase in FcR expression as compared to cells treated with conditioned medium (Figure 3). This suggests that the M?N cell line Letermovir is able to respond to an activating stimulus. These results show that the increase in the expression of FcRIIB/III induced by RSV persistence is not mediated by extracellular factors released by persistently infected cells. Open in a separate window Figure 3 FcRIIB/RIII expression in M?N after treatment with M?N or M?P conditioned medium (CM). M?N were treated with either 12 h- or 24 Letermovir h-CM from M?N or M?P, or with heat-killed NTHi as control (see Materials and Methods for details). After 24 h, FcRIIB/RIII was analyzed by flow cytometry. Results are expressed as mean 1 SD of mean fluorescence intensity in three independent experiments. 2.1.3. RSV Persistence does not Affect FcRIIB/RIII Endocytosis In order to determine whether the increase in membrane FcRIIB/RIII was due to impaired receptor endocytosis, we measured the rate of FcRIIB/RIII internalization as described in Materials and Methods. We found similar FcRs internalization kinetics in both M?N and M?P. Average decreases in MFI at 120 min were 14.82 and 15.79 units for M?N and M?P, respectively, suggesting that FcRIIB/RIII receptors endocytosis is not significantly altered by RSV persistence (Figure 4). Open in a separate window Figure 4 Internalization of FcRIIB/RIII in M?N and M?P. Internalization kinetics of mAb 2.4G2-FcRIIB/RIII complexes was monitored by flow cytometry during 120 min, as described in Materials and Methods. Results are expressed as the mean 1 SD from three independent experiments. No significant difference was observed between M?N and M?P in the net amount of internalized mAb 2.4G2-FcRIIB/RIII complexes. 2.1.4. Intracellular Levels of FcRIIB/RIII Proteins Are Increased in M?P In order to investigate whether the increase of FcRIIB/RIII expression on the membrane of M?Ps was associated with increased receptor synthesis, we determined the total amount of receptor protein (membrane and intracellular) in the cells using flow cytometry. We found out that M?Ps have more FcRIIB/RIII protein than M?Ns, both on the cell surface and intracellularly Rabbit polyclonal to GR.The protein encoded by this gene is a receptor for glucocorticoids and can act as both a transcription factor and a regulator of other transcription factors.The encoded protein can bind DNA as a homodimer or as a heterodimer with another protein such as the retinoid X receptor.This protein can also be found in heteromeric cytoplasmic complexes along with heat shock factors and immunophilins.The protein is typically found in the cytoplasm until it binds a ligand, which induces transport into the nucleus.Mutations in this gene are a cause of glucocorticoid resistance, or cortisol resistance.Alternate splicing, the use of at least three different promoters, and alternate translation initiation sites result in several transcript variants encoding the same protein or different isoforms, but the full-length nature of some variants has not been determined. (Figure 5). These results suggest that viral persistence induces the upregulation of FcRIIB/RIII synthesis. Open in a separate window Figure 5 Total FcRIIB/RIII protein in M?N and M?P. Cell-membrane and total FcRIIB/RIII protein content were determined in non-permeabilized or permeabilized M?N and M?P cells. FcRIIB/RIII expression was evaluated with 2.4G2 monoclonal antibody and analyzed by flow cytometry. Results are expressed as mean Letermovir 1 SD from three Letermovir independent experiments, using different.