The CD 28.2 monoclonal antibody reacts with human and monkey CD28，a45kDa costimulatory receptory receptor and a member of the Ig superfamily.CD28is expressed by thymocytes，most peripheral T cells，and NK cells.CD28is a receptor forCD80（B7-1）and CD86（B7-2）。Signaling through CD28augments IL-2and IL-2receptor expression as well as cytotoxicity of CD3-activated T cells.The CD28.2antibody has been shown to stimulate the proliferation of human T cellsin vitro。
Zhao，Y.，et al.（2019）。“PD-L1:CD80Cis-Heterodimer Triggers the Co-stimulatory Receptor CD28While Repressing the Inhibitory PD-1and CTLA-4Pathways”Immunity51（6）：1059-1073.e1059。PubMed
Combined immunotherapy targeting the immune checkpoint receptors cytotoxic T-lymphocyte-associated protein4（CTLA-4）and programmed cell death1（PD-1），or CTLA-4and the PD-1ligand（PD-L1）exhibits superior anti-tumor responses compared with single-agent apy。Here，we examined the molecular basis for this synergy.Using reconstitution assays with fluorescence readouts，we found that PD-L1and the CTLA-4ligand CD80heterodimerize in cis but not trans.Quantitative biochemistry and cell biology assays revealed that PD-L1:CD80cis-heterodimerization inhibited both PD-L1:PD-1and CD80:CTLA-4interactions through distinct mechanisms but revatity the CD cell co-stimulatory receptor CD28.Furthermore，PD-L1expression antigen-presenting cells（APCs）prevented CTLA-4-mediated trans-endocytosis of CD80。Atezolizumab（anti-PD-L1），but not anti-PD-1，reduced cell surface expression of CD80on APCs，and this effect was negated by co-blockade of CTLA-4with ipilimumab（anti-CTLA-4）。Thus，PD-L1exerts an immunostimulatory effect by repressing the CTLA-4axis；this has implications to the synergy of anti-PD-L1 and anti-CTLA-4combination therapy。
in vitroT cell stimulation/activation
Blewett，M.M.，et al.（2016）。“Chemical proteomic map of dimethyl fumarate-sensitive cysteines in primary human T cells”Sci Signal9（445）：rs10。PubMed
Dimethyl fumarate（DMF）is an electrophilic drug that is used to treat autoimmune conditions，including multiple sclerosis and psoriasis.The mechanism of action of DMF is unclear but may involve the covalent modification of proteins or DMF serving asa prodrug this converted to monomethyl fumarate（MMF）。We found that DMF，but not MMF，blocked the activation of primary human and mouse T cells.Using a quantitative，site-specific chemical proteomic platform，we determined the DMF sensitivity of>2400cysteine residues in human T cells.Cysteines sensitive to DMF，but not MMF，were identified in several proteins with established biochemical or genetic links to T cell function，including protein kinase Ctheta（PKCtheta）。DMF blocked the association of PKCtheta with the costimulatory receptor CD28by perturbing a CXC motif in the C2domain of this kinase.Mutation of these DMF-sensitive cysteines also impaired PKCtheta-CD28 interactions and T cell activation，designating the C2domain of PKCthe as a key functional，electrophile-sensing module important for T cell biology。
in vitroT cell stimulation/activation
Oh，Y.M.，et al.（2015）。“Ndrg1is a T-cell clonal anergy factor negatively regulated by CD28costimulation and interleukin-2”Nat Commun6:8698。PubMed
Induction of T-cell clonal anergy involves serial activation of transcription factors，including NFAT and Egr2/3.However，downstream effector mechanisms of these transcription factors are not fully understood yet.Here we identify Ndrg1as an anergy factor induced by Egr2.Ndrg1is upregulated by anergic signalling and maintained at high levels in resting anergic T cells.Overexpression of Ndrg and maintainect of micks and gicks the anout the gene prevents anergy induction.Interestingly，Ndrg1is phosphorylated and degraded by CD28signalling in a proteasome-dependent manner，explaining the costimulation dependence of anergy prevention.Similarly，IL-2treatment of anergic T cells，under conditions that lead to the reversal of anergy，also induces Ndraction and Final，older Ndrg1-deficient mice show T-cell hyperresponsiveness and Ndrg1-deficient T cells aggravate inducible autoimmune inflammation.Thus，Ndrg1contributes to the maintenance of clonal anergy and inhibition of T-cell-mediated inflammation。
in vitroT cell stimulation/activation
Edwards，L.J.，et al.（2015）。“Signal transducer and activator of transcription（STAT）3inhibition delays the onset of lupus nephritis in MRL/lpr mice”Clin Immunol158（2）：221-230。PubMed
The transcription factor STAT3is overexpressed and hyperactivated in T cells from SLE patients.STAT3plays a central role in T cell differentation into Th17andT follicular helper cells，two subsets thatorchestrate autoimmune responses in SLE.Moreover，STAT3is important in chemokine-mediated T cell migration.To better understand its role in SLE，we inhibited STAT3in lupus-prone mice using the small molecule Stattic.Stattic-treated mice exhibited delayed onset of proteinuria（3weeks later than controls），and had lower levels of anti-dsDNA antibodies and inflammatory cytokines.Inhibitor treatment reduced lymphadenopathy，resulted ina3-fold decrease in total T cell number，anda4-fold decrease in the numbers of Tfollicular helper cells.In vitro experiments showed that Stattic-treated T cells exhibition decreased proliferation and a decrease in ability to migrate to CXCL12.We propose that STAT3inhibition represents atherapeutic target in SLE，particulaly riphus。
流动周期，流动周期
Leonard，J.A.，et al.（2011）。“HIV-1 Nef disrupts intracellular trafficking of major histocompatibility complex class I，CD4，CD8，and CD28by distinct pathways that share common elements”J Virol85（14）：6867-6881。PubMed
The Nef protein is an important HIV virulence factor that promotes the degradation of host proteins to augment virus production and facilitate immune evasion.The best-characterized targets of Nef are major histocompatibility complex class I（MHC-I）and CD4，but Nef also has been reported to target several other proteins，including CD8beta，CD28，CD80，CD86，and CD1d.To compare and contrast the effects of Nef on each protein，we constructed a panel of chimeric proteins in which the extracellular and transmembrane regions of the MHC-IalleHLA-A of CD4、CD28、，CD8beta，CD80，CD86，and CD1d.We found that Nef coprecipitated with and disrupted the expression of molecules with cytoplasmic tails from MHC-I HLA-A2，CD4，CD8beta，and CD28，but Nef did not bind to or alter the expression of molecules with cytoplasmictails from CD，and CD86，addition and，we used short interfering RNA（siRNA）knockdown and coprecipitation experiments to implicate AP-1as a cellular cofactor for Nef in the downmodulation of both CD28and CD8beta。The interaction with AP-1required for CD28and CD8beta differed from the AP-1interaction required for MHC-Idownmodulation in that it was mediated through the dileucine motif within Nef（LL（164165）AA）and did not require the tyrosine binding pocket of the AP-1mu subunit。本发明提供了一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，一种集成电路，and CD8.These studies provide important new information on the similarities and differences with which Nef affects intracellular trafficking and help focus future research on the best potential pharmaceutical targets。
流动周期，流动周期
Rout，N.，et al.（2010）。“Paucity of CD4+natural killer T（NKT）lymphocytes in sooty mangabeys is associated with lack of NKT cell depletion after SIV infection”PLoS One5（3）：e9787。PubMed
Lack of chronic immune activation in the presence of persistent viremia is akey feature that distinguishes nonpathogenic simian immunodeficiency virus（SIV）innatural hosts from pathogenic SIV and HIV infection。To elucidate novel mechanisms downmodulating immune activation in natural hosts of SIV infection，we investigated natural killer T（NKT）lymphocytes in sooty mangabeys。NKT lymphocytes are a potent immunoregulatory arm of the innate immune system that recognize glycolipid antigens presented on the nonpolymorphic MHC-class I-like CD1d molecules.In cross-sectional analysis of 50 SIV-negative and 50 naturally SIV-infected sooty mangabeys，ligand alpha-galactosylceramide loaded CD1d tetramers co-staining with Valpha24-positive invariant NKT lymphocytes were detected at frequencies>or=0.002%of circulating T lymphocytes in approximately half of the animals.In contrast to published reports in Asian macaques，sooty mangabey NKT lymphocytes consisted of CD8（+）and CD4/CD8 double-negative T1 lymphocytes that were CXCR3-positive and CCR5-negative suggesting that they trafficked to sites of inflammation withot being susceptible to SIV infection。Consist with these findings，there was no difference in the frequency or phenotype of NKT lymphocytes between SIV-negative and SIV-infected sooty mangabeys.On stimulation with alpha-galactosylceramide loaded on human on human CD1d molecules，sooty mangabey NKT lymphocytes underwent derange and Ften NF-alpha，IL-2，IL-13，and IL-10，indicating the presence of both effector and immunoregulatory functional capabilities.The unique absence of CD4（+）NKT lymphocytes in sooty mangabeys，combined with their IL-10cytokine-secreting ability and preservation following SIV infection，raises the possibility that NKT lymphocytes might play arole in downmodulating immune activation in SIV-infected sooty mangabeys。
Immunohistochemistry（frozen）
Tazi，A.，et al.（1999）。“Evidence that Langerhans cells in adult pulmonary Langerhans cell histiocytosis are mature dendritic cells:importance of the cytokine microenvironment”J Immunol163（6）：3511-3515。PubMed
Because Langerhans cells（LC）in peripheral tissues are generally“immature”cells with poor lymphostimulatory activity，the contribution of immune responses initiated by LC to the pathogenesis of pulmonary LC histiocytosis（LCH）has been uncertain。In this study we demonstrate that LC accumulating in LCH granulomas are phenotypically similar to mature lymphostimulatory dendritiic cells present in lymphoid organs.LC in LCH granulomas intensely expressed B7-1andB7-2 molecules，whereas normal pulmonary LC and LC accumulating in other pathologic lung disorders did not express these costimulatory molecules.The presence of B7+LC in LCH granulomas was associated with the expression in these lesions，but not at other sites in the lung，of a unique profile of cytokines，TNF-alpha，and IL-1beta and the absence of IL-10）that is known to promote thein vitrodifferentiation of LC into cells expressing alymphostimulatory phenotype.Finally，LCH granulomas were the only site where CD154-positive T cells could be identified in close contact with LC intensely expressing CD40Ags.Taken together，these results strongly support the idea that an abnormal immune response initiated by LC may participate in the pathogenesis of pulmonary LCH，and suggest that therapeutic strategies aimed at modifying the lymphostimulatory phenotype of LC may be useful in the treatment of this disorder。
Immunohistochemistry（frozen）
Battifora，M.，et al.（1998）。“B7.1 costimulatory molecule is expressed on thyroid follicular cells in Hashimoto’s thyroiditis，but not in Graves’disease”J Clin Endocrinol Metab83（11）：4130-4139。PubMed
The molecules of the B7family play a major role in T-lymphocyte costimulation through interaction with their counterreceptors CD28and CTLA4.In the present study，we analyzed the possible expression of B7molecules on surgically removed thyroid tissue of patients with autoimmune[Hashimoto’s（HTitis’s）sease（GD）]or nonautoimmune[nontoxic goiter（NTG）or papillary cancer（PC）]thyroid diseases。We found clear positivity of thyroid follicular cells for B7.1 in HT but not in GD，nor in nonautoimmune specimens（NTG，PC）using in situ analysis by alkaline phosphatase anti-alkaline phosphatase（APAAP）technique。Double immunostaining experiments in combination with an anti-human thyroglobulin antibody confirmed follicular B7.1 localization.On the contrary，no follicular B7.2 expression was observed in any specimen analyzed.These findings were confirmed by immunofluorescence flow cytometry on isollicular cells.The cytokines IL1beta and LPS were able to induce de novo B7.1 expression cultured thyroid follicular cells.Intrathroid procells stimulation via the B7ligandCD28，even in the absence of IL2.Moreover preliminary evidence was obtained foran inhibitory effect of anti-B7.1 mAb on T-cell proliferation in coculture with isollicular cells.It is conceivable that in HT，expression of B7.1 on follicular cells，together with MHclang II，could provide a local costimulatory signal forT-lymphocyte differentiation toward the type1cytokine secretion pattern and maintenance of the autoimmune process。
