Selective proliferation of human γδ T cells in vitro

The effect of monoethylphosphate (MEP, commercial available or synthesized) together with IL-2 on the selective proliferation of human γ~δ T cells in Vitro from peripheral blood mononuclear cells (PBMC) of healthy donors and of cancer patients was investigated. The γ~δ T cells were stimulated by MEP to proliferate in a dose-dependent manner. The effect of synthesized MEP was 10 times greater than that of commercial MEP. When the PBMCs of healthy donors were cultured for 25 d in the medium containing different concentrations of MEP, the total cell number increased about 1000-3000 fold; and the ratio of γ~δ T cells reached to 70-80%. The selective expansion of γ~δ T cells depended on the synergic action of MEP and IL-2. The bulk cultured γ~δ T cells exhibited obvious cytotoxic activities against allogenic tumor cell lines (SQ-5,K562 alld Daudi) and autologous tumor cells. The culture system described here not only offers a simple method for obtaining a large number of γ~δ T cells which may become a new effector in the adoptive immunotherapy, but also provides a useful model for the further studies of the structure and function of γ~δ T cells in vitro.

Effects of Sanchi extract on the activation and proliferation of murine lymphocytes and NO secretion by peritoneal macrophages in vitro

The aim of this study is to elucidate the molecular and cellular mechanisms underlying the immunosuppressive effect of Sanchi extract （SE） via investigating the effects of SE on the activation and proliferation of murine lymphocytes and NO secretion by peritoneal macrophages in vitro. ConA was used to activate lymphecytes, and expression of CD69 on T cells and CFSE labeled cell division were detected by flow cytometry. Murine peritoneal macrophages were stimulated with LPS or lymphocytes culture supernate （LCS） and the concentration of NO was determined by Griess reagent assay. After 6 h of culture, SE ranging from 50 to 100μg/ml downregulated CD69 expression on ConA-activated T cells, while SE ranging from 12.5 to 100μg/ml inhibited the proliferative response of lymphocytes to ConA. Additionally, SE （12.5-100μg/ml） inhibited secretion of NO by peritoneal macrophages stimulated by LPS or LCS. This study reveals that SE inhibits the activation and proliferation of routine lymphocytes and NO secretion by peritoneal macrophages.

The precursor frequency of alloreactive CTLs is proportional to the number of T cell epitope specificities

The aim of this study is to find the experimental evidence that the precursor frequency of alloreactive CTLs is proportional to the number of the T-cell epitope specificities. The number of T-cell epitope specificities was manipulated by pulsing different humor of HLA-A2 restricted peptide（s） onto the T2 cells, which acted as stimulating cells to elicit allo-reaction by co-culturing with peripheral blood lymphocytes （PBLs） of HLA-A2 negative individual. Ten HLA-A2 restricted peptides （all were normal cell components ） were synthesized, and cell peptide extract was prepared by frozen and thawed. T2 cells loaded with different number of peptide（s） were co-cultured with PBLs of an HLA-A2 negative individual; the latter were stained with PKH67 in advance. Then the proliferation was monitored with flow cytometry, and the precursor frequency of the effector cells was ＇analyzed by the ModFit Software. After 6 d of culture, no proliferation was observed in the bulk culture of PBL alone, and obvious proliferation took place when PBLs of the HLA-A2 negative were co-cultured with T2 cells loaded with or without loading peptide（ s）. The precursor frequency of the alloreactive CTLs was 0.052 819 for co-culture with T2 cells loaded without peptide; however it was 0. 030 429 for T2 cells with EBV/LMP2A and 0. 030 528 for T2 cells loaded with a single autogeneic peptide, and increased up to 0. 144 942 for T2 cells loaded with 10 autogeneic peptides; the precursor frequency was 0. 203 649 when co-cultured with T2 cells loaded with miscellaneous peptides extracted from the cytoplasm of T2 cells. This study reveals that the precursor frequency of alloreactive CTLs is proportional to the number of T-cell epitope specificities, and independent of the density of the allogeneic HLA Class Ⅰ molecule. Our findings support the hypothesis that the alloreactive T cell populations comprise miscellaneous T cell clones; each is specific to corresponding pMHC. The novel constellation of peptides presented by allogeneic MHC molecules makes thousands of different epitopes, which account for the exceptional high precursor frequency of alloreactive T cells.

A Delayed HIV Infection Model with the Homeostatic Proliferation of CD4^(+)T Cells

In this paper,we investigate a delayed HIV infection model that considers the homeostatic prolif-eration of CD4^(+)T cells.The existence and stability of uninfected equilibrium and infected equilibria(smaller and larger ones)are studied by analyzing the characteristic equation of the system.The intracellular delay does not affect the stability of uninfected equilibrium,but it can change the stability of larger positive equilibrium and Hopf bifurcation appears inducing stable limit cycles.Furthermore,direction and stability of Hopf bifur-cation are well investigated by using the central manifold theorem and the normal form theory.The numerical simulation results show that the stability region of larger positive equilibrium becomes smaller as the increase of time delay.Moreover,when the maximum homeostatic growth rate is very small,the larger positive equilibrium is always stable.On the contrary,when the rate of supply of T cells is very small,the larger positive equilibrium is always unstable.

Nanoparticles (NPs)-mediated Siglec15 silencing and macrophage repolarization for enhanced cancer immunotherapy

cell infiltration and proliferation in tumor tissues are the main factors that significantly affect the therapeutic outcomes of cancer immunotherapy.Emerging evidence has shown that interferon-gamma(IFN)could enhance CXCL9 secretion from macrophages to recruit T cells,but Siglec15 expressed on TAMs can attenuate T cell proliferation.Therefore,targeted regulation of macrophage function could be a promising strategy to enhance cancer immunotherapy via concurrently promoting the infiltration and proliferation of T cells in tumor tissues.We herein developed reductionresponsive nanoparticles(NPs)made with poly(disulfide amide)(PDSA)and lipid-poly(ethylene glycol)(lipid-PEG)for systemic delivery of Siglec15 siRNA(siSiglec15)and IFN for enhanced cancer immunotherapy.After intravenous administration,these cargo-loaded could highly accumulate in the tumor tissues and be efficiently internalized by tumor-associated macrophages(TAMs).With the highly concentrated glutathione(GSH)in the cytoplasm to destroy the nanostructure,the loaded IFN and si-Siglec15 could be rapidly released,which could respectively repolarize macrophage phenotype to enhance CXCL9 secretion for T cell infiltration and silence Siglec15 expression to promote T cell proliferation,leading to significant inhibition of hepatocellular carcinoma(HCC)growth when combining with the immune checkpoint inhibitor.The strategy developed herein could be used as an effective tool to enhance cancer immunotherapy.

Cutaneous Dengue Virus Inoculation Triggers Strong B Cell Reactions but Contrastingly Poor T Cell Responses

Dengue is a global health problem without current specific treatment nor safe vaccines available.While severe dengue is related to pre-existing non-neutralizing dengue virus(DENV)antibodies,the role of T cells in protection or pathology is unclear.Using cutaneous DENV infection in immunocompetent mice we previously showed the generation of PNA+germinal centers(GCs),now we assessed the activation and proliferation of B and T cells in draining lymph nodes(DLNs).We found a drastic remodelling of DLN compartments from 7 to 14 days post-infection(dpi)with greatly enlarged B cell follicles,occupying almost half of the DLN area compared to*24%in na?ve conditions.Enormous clusters of proliferating(Ki-67+)cells inside B follicles were found 14 dpi,representing*33%of B cells in DLNs but only*2%in noninfected mice.Inside GCs,we noticed an important recruitment of tingle body macrophages removing apoptotic cells.In contrast,the percentage of paracortex area and total T cells decreased by 14–16 dpi,compared to controls.Scattered randomly distributed Ki-67+T cells were found,similar to non-infected mice.CD69 expression by CD4+and CD8+T cells was minor,while it was remarkable in B cells,representing 1764.7%of change from basal levels 3 dpi.The apparent lack of T cell responses cannot be attributed to apoptosis since no significant differences were observed compared to noninfected mice.This study shows massive B cell activation and proliferation in DLNs upon DENV infection.In contrast,we found very poor,almost absent CD4+and CD8+T cell responses.