Function Of CD4 Research Articles

CD5 blockade, a novel immune checkpoint inhibitor, enhances T cell anti-tumour immunity and delays tumour growth in mice harbouring poorly immunogenic 4T1 breast tumour homografts.

CD5 is a member of the scavenger receptor cysteine-rich superfamily that is expressed on T cells and a subset of B cells (B1a) cell and can regulate the T cell receptor signaling pathway. Blocking CD5 function may have therapeutic potential in treatment of cancer by enhancing cytotoxic T lymphocyte recognition and ablation of tumour cells. The effect of administering an anti-CD5 antibody to block or reduce CD5 function as an immune checkpoint blockade to enhance T cell anti-tumour activation and function in vivo has not been explored. Here we challenged mice with poorly immunogenic 4T1 breast tumour cells and tested whether treatment with anti-CD5 monoclonal antibodies (MAb) in vivo could enhance non-malignant T cell anti-tumour immunity and reduce tumour growth. Treatment with anti-CD5 MAb resulted in an increased fraction of CD8+ T cells compared to CD4+ T cell in draining lymph nodes and the tumour microenvironment. In addition, it increased activation and effector function of T cells isolated from spleens, draining lymph nodes, and 4T1 tumours. Furthermore, tumour growth was delayed in mice treated with anti-CD5 MAb. These data suggest that use of anti-CD5 MAb as an immune checkpoint blockade can both enhance activation of T cells in response to poorly immunogenic antigens and reduce tumour growth in vivo. Exploration of anti-CD5 therapies in treatment of cancer, alone and in combination with other immune therapeutic drugs, is warranted.

Cancer cell-derived CD69 induced under lipid and oxygen starvation promotes ovarian cancer progression through fibronectin.

Cancer tissues generally have molecular oxygen and serum component deficiencies because of poor vascularization. Recently, we revealed that ICAM1 is strongly activated through lipophagy in ovarian clear cell carcinoma (CCC) cells in response to starvation of long-chain fatty acids and oxygen and confers resistance to apoptosis caused by these harsh conditions. CD69 is a glycoprotein that is synthesized in immune cells and is associated with their activation through cellular signaling pathways. However, the expression and function of CD69 in nonhematological cells is unclear. Here, we report that CD69 is induced in CCC cells as in ICAM1. Mass spectrometry analysis of phosphorylated peptides followed by pathway analysis revealed that CD69 augments CCC cell binding to fibronectin (FN) in association with the phosphorylation of multiple cellular signaling molecules including the focal adhesion pathway. Furthermore, CD69 synthesized in CCC cells could facilitate cell survival because the CD69-FN axis can induce epithelial-mesenchymal transition. Experiments with surgically removed tumor samples revealed that CD69 is predominantly expressed in CCC tumor cells compared with other histological subtypes of epithelial ovarian cancer. Overall, our data suggest that cancer cell-derived CD69 can contribute to CCC progression through FN.

CD5 Controls Gut Immunity by Shaping the Cytokine Profile of Intestinal T Cells.

CD5 is constitutively expressed on all T cells and is a negative regulator of lymphocyte function. However, the full extent of CD5 function in immunity remains unclear. CD5 deficiency impacts thymic selection and extra-thymic regulatory T cell generation, yet CD5 knockout was reported to cause no immune pathology. Here we show that CD5 is a key modulator of gut immunity. We generated mice with inducible CD5 knockdown (KD) in the autoimmune-prone nonobese diabetic (NOD) background. CD5 deficiency caused T cell-dependent wasting disease driven by chronic gut immune dysregulation. CD5 inhibition also exacerbated acute experimental colitis. Mechanistically, loss of CD5 increased phospho-Stat3 levels, leading to elevated IL-17A secretion. Our data reveal a new facet of CD5 function in shaping the T cell cytokine profile.

Animal models for human group 1 CD1 protein function

The CD1 antigen presenting system is evolutionary conserved and found in mammals, birds and reptiles. Humans express five isoforms, of which CD1a, CD1b and CD1c represent the group 1 CD1-molecules. They are recognized by T cells that express diverse αβ-T cell receptors. Investigation of the role of group 1 CD1 function has been hampered by the fact that CD1a, CD1b and CD1c are not expressed by mice. However, other animals, such as guinea pigs or cattle, serve as alternative models and have established basic aspects of CD1-dependent, antimicrobial immune functions. Group 1 CD1 transgenic mouse models became available about ten years ago. In a series of seminal studies these mouse models coined the mechanistical understanding of the role of the corresponding CD1 restricted T cell responses. This review gives a short overview of available animal studies and the lessons that have been and still can be learned.

Abstract 917: Functional blocking of CD5 on T cells to enhance the efficacy of therapeutic PD-1 blockade in treatment of mouse 4T1 breast tumors

Abstract Blockade of programmed cell death protein 1 (PD-1) is approved for treatment of multiple human cancers and is the focus of multiple studies due to its key role in T cell function. However, only patients with ‘'hot'' tumors (i.e. those with increased numbers of tumor-infiltrating CD8+ T cells) respond well to the blockade. This suggests that new strategies to increase infiltration of CD8+ T cells into tumors will increase the number of tumor types and patients benefiting from anti-PD-1 therapy. CD5, a member of the scavenger receptor cysteine-rich (SRCR) superfamily, is expressed on T cells and a subset of B cells (B1a). It can attenuate TCR signaling and impair cytotoxic T lymphocyte (CTL) activation. CD5 knockout mice have increased anti-tumor immunity and reduced homograft tumor growth: reducing CD5 on CTLs may be therapeutically beneficial to enhance the anti-tumor response and increase tumor-infiltrating CD8+ T cells. We report that in vivo administration of anti-CD5 blocking MAb treatment increased primary T cell activation in response to 4T1 tumor cell homografts and ex vivo activation as measured by increased CD69, Fas, Fas ligand, IFNγ, PD-1, and apoptosis. Further, anti-CD5 treatment enhanced the capacity of primary T cells to kill 4T1 tumor cells ex vivo. Mice receiving anti-CD5 and anti-PD-1 in combination exhibited increased overall survival compared to mice treated with either agent alone. These data support the potential of blockade of CD5 function to enhance T cell-mediated anti-tumor immunity and PD-1 blockade treatment. Citation Format: Faizah Alotaibi, Mateusz Rytelewski, Rene Figueredo, Ronak Zareardalan1, Saman Maleki Vareki, Xiufen Zheng, Meng Zhang, Peter Ferguson, Mikal El-Hajjar, Yousef Najajreh, Wei-ping Min, James Koropatnick. Functional blocking of CD5 on T cells to enhance the efficacy of therapeutic PD-1 blockade in treatment of mouse 4T1 breast tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 917.

CD5 dynamically calibrates basal NF-κB signaling in T cells during thymic development and peripheral activation

Immature T cells undergo a process of positive selection in the thymus when their new T cell receptor (TCR) engages and signals in response to self-peptides. As the T cell matures, a slew of negative regulatory molecules, including the inhibitory surface glycoprotein CD5, are up-regulated in proportion to the strength of the self-peptide signal. Together these regulators dampen TCR-proximal signaling and help avoid any subsequent peripheral activation of T cells by self-peptides. Paradoxically, antigen-specific T cells initially expressing more CD5 (CD5hi) have been found to better persist as effector/memory cells after a peripheral challenge. The molecular mechanisms underlying such a duality in CD5 function is not clear. We found that CD5 alters the basal activity of the NF-κB signaling in resting peripheral T cells. When CD5 was conditionally ablated, T cells were unable to maintain higher expression of the cytoplasmic NF-κB inhibitor IκBα. Consistent with this, resting CD5hi T cells expressed more of the NF-κB p65 protein than CD5lo cells, without significant increases in transcript levels, in the absence of TCR signals. This posttranslationally stabilized cellular NF-κB depot potentially confers a survival advantage to CD5hi T cells over CD5lo ones. Taken together, these data suggest a two-step model whereby the strength of self-peptide-induced TCR signal lead to the up-regulation of CD5, which subsequently maintains a proportional reserve of NF-κB in peripheral T cells poised for responding to agonistic antigen-driven T cell activation.

CD5 blockade enhances ex vivo CD8+ Tcell activation and tumour cell cytotoxicity.

CD5 is expressed on Tcells and a subset of B cells (B1a). It can attenuate TCR signalling and impair CTL activation and is a therapeutic targetable tumour antigen expressed on leukemic T and B cells. However, the potential therapeutic effect of functionally blocking CD5 to increase Tcell anti-tumour activity against tumours (including solid tumours) has not been explored. CD5 knockout mice show increased anti-tumour immunity: reducing CD5 on CTLs may be therapeutically beneficial to enhance the anti-tumour response. Here, we show that ex vivo administration of a function-blocking anti-CD5 MAb to primary mouse CTLs of both tumour-naïve mice and mice bearing murine 4T1 breast tumour homografts enhanced their capacity to respond to activation by treatment with anti-CD3/anti-CD28 MAbs or 4T1 tumour cell lysates. Furthermore, it enhanced TCR signalling (ERK activation) and increased markers of Tcell activation, including proliferation, CD69 levels, IFN-γ production, apoptosis and Fas receptor and Fas ligand levels. Finally, CD5 function-blocking MAb treatment enhanced the capacity of CD8+ Tcells to kill 4T1-mouse tumour cells in an ex vivo assay. These data support the potential of blockade of CD5 function to enhance Tcell-mediated anti-tumour immunity.

IL-10-producing regulatory B cells exhibit functional defects and play a protective role in severe endotoxic shock

Dysregulated host immune homeostasis in sepsis is life-threatening even after a successfully treated bacterial infection. Lipopolysaccharide (LPS) is an endotoxin that is a major contributor to the aberrant immune responses and endotoxic shock in gram-negative bacterial sepsis. However, the current knowledge of the role of B cells in endotoxic shock is limited. Here, we report that CD1d expression in B cells and the percentage of CD5+CD1dhi regulatory B (Breg) cells decreased in a mouse model of endotoxic shock. Interestingly, IL-10 but not FasL expression in CD5+CD1dhi Breg cells in response to endotoxin was dramatically reduced in severe septic shock mice, and the regulatory function of CD5+CD1dhi Breg cells in vitro to control the Th1 response was also diminished. Adoptive transfer of CD5+CD1dhi Breg cells from healthy WT mice but not IL-10 deficient mice downregulated the IFN-γ secretion in CD4+ T cells and conferred protection against severe endotoxic shock in vivo. Our findings demonstrate the change and notable therapeutic potential of IL-10-producing Breg cells in endotoxic shock.

Most CD5+ B Lymphocytes Secrete IL-10 in Autoimmune Hemolytic Anemia/Evans Syndrome Patients

Objective:Autoimmune hemolytic anemia (AIHA)/Evans syndrome is a form of immune-related cytopenia characterized by autoantibodies directed against red blood cells. A subset of B lymphocytes expressing CD5 is found in patients with AIHA/Evans syndrome. Previous studies have shown that the number of CD5+ B lymphocytes is correlated with the severity of AIHA/Evans syndrome. IL-10 can be induced in various types of human B cells, including naive, memory, and CD5+B cells, following B-cell activation by Th-cell-dependent and TLR-dependent signals. This study is to investigate the secretion function of CD5+ B lymphocytes in AIHA/Evans syndrome (ES) patients.Methods:25 untreated AIHA/ES patients, 28 remission AIHA/ES patients and 25 healthy controls (HCs) were enrolled in this study. The quantity of CD5+B lymphocytes which produce interleukin-10 (IL-10) (CD5+IL-10+) were detected by flow cytometry. CD5+ B lymphocytes were sorted from Peripheral blood (PB) by CytoFLEX Flow Cytometer. The expression of IL-10 mRNA in CD5+ B cells were measured by real-time PCR (RT-PCR). The concentrations of IL-10 in serum were detected by Enzyme-linked Immunosorbent assay (ELISA).Results:The percentage of CD5+IL-10+B cells in CD5+ B lymphocytes in newly diagnosed patients was 82.18±14.78%, which being significantly higher than that of remission AIHA/ES patients (56.68±24.39%) and HC (51.90±22.95%)(p<0.05). The percentage of CD5+IL-10+ B cells in CD5+ B lymphocytes in newly diagnosed patients was negatively correlated with their serum level of hemoglobin, C3 (P<0.05) and positively correlated with their serum level of LDH, TBIL and IBIL (P<0.05).The expression level of CD5+ B lymphocytes IL-10 mRNA in newly diagnosed patients (49.34±22.84) was higher than that of remission patients (3.97±3.83) and HC (1.78±1.66) (P<0.05).The concentration of IL-10 in serum in newly diagnosed patients (4.01±1.54 pg/ml) was lower than that of remission patients (5.08±1.72pg/ml) and HC (5.70±1.60pg/ml) (P<0.05).Conclusions:Most CD5+ B lymphocytes secrete IL-10 in AIHA/Evans patients and are positively correlated with the severity of the disease. The increased quantity of CD5+IL-10+ B cells and the decreased cytokines-secreted level maybe involved in the occurrence of AIHA/Evans syndrome. DisclosuresNo relevant conflicts of interest to declare.

Molecular basis of CD22 function and therapeutic targeting

Molecular basis of CD22 function and therapeutic targeting

T Cell Calcium Signaling Regulation by the Co-Receptor CD5.

Calcium influx is critical for T cell effector function and fate. T cells are activated when T cell receptors (TCRs) engage peptides presented by antigen-presenting cells (APC), causing an increase of intracellular calcium (Ca2+) concentration. Co-receptors stabilize interactions between the TCR and its ligand, the peptide-major histocompatibility complex (pMHC), and enhance Ca2+ signaling and T cell activation. Conversely, some co-receptors can dampen Ca2+ signaling and inhibit T cell activation. Immune checkpoint therapies block inhibitory co-receptors, such as cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) and programmed death 1 (PD-1), to increase T cell Ca2+ signaling and promote T cell survival. Similar to CTLA-4 and PD-1, the co-receptor CD5 has been known to act as a negative regulator of T cell activation and to alter Ca2+ signaling and T cell function. Though much is known about the role of CD5 in B cells, recent research has expanded our understanding of CD5 function in T cells. Here we review these recent findings and discuss how our improved understanding of CD5 Ca2+ signaling regulation could be useful for basic and clinical research.

Molecular basis of human CD22 function and therapeutic targeting

CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As a B-cell-restricted antigen, CD22 is targeted in therapies against dysregulated B cells that cause autoimmune diseases and blood cancers. Here we report the crystal structure of human CD22 at 2.1 Å resolution, which reveals that specificity for α2-6 sialic acid ligands is dictated by a pre-formed β-hairpin as a unique mode of recognition across sialic acid-binding immunoglobulin-type lectins. The CD22 ectodomain adopts an extended conformation that facilitates concomitant CD22 nanocluster formation on B cells and binding to trans ligands to avert autoimmunity in mammals. We structurally delineate the CD22 site targeted by the therapeutic antibody epratuzumab at 3.1 Å resolution and determine a critical role for CD22 N-linked glycosylation in antibody engagement. Our studies provide molecular insights into mechanisms governing B-cell inhibition and valuable clues for the design of immune modulators in B-cell dysfunction.

Exonal switch down-regulates the expression of CD5 on blasts of acute T cell leukaemia.

To date, CD5 expression and its role in acute T cell lymphoblastic leukaemia (T-ALL) have not been studied closely. We observed a significant reduction in surface expression of CD5 (sCD5) on leukaemic T cells compared to autologous non-leukaemic T cells. In this study, we have shown the molecular mechanism regulating the expression and function of CD5 on leukaemic T cells. A total of 250 patients suffering from leukaemia and lymphoma were immunophenotyped. Final diagnosis was based on their clinical presentation, morphological data and flow cytometry-based immunophenotyping. Thirty-nine patients were found to be of ALL-T origin. Amplification of early region of E1A and E1B transcripts of CD5 was correlated with the levels of surface and intracellular expression of CD5 protein. Functional studies were performed to show the effect of CD5 blocking on interleukin IL-2 production and survival of leukaemic and non-leukaemic cells. Lack of expression of sCD5 on T-ALL blasts was correlated closely with predominant transcription of exon E1B and significant loss of exon E1A of the CD5 gene, which is associated with surface expression of CD5 on lymphocytes. High expression of E1B also correlates with increased expression of cytoplasmic CD5 (cCD5) among leukaemic T cells. Interestingly, we observed a significant increase in the production of IL-2 by non-leukaemic T cells upon CD5 blocking, leading possibly to their increased survival at 48 h. Our study provides understanding of the regulation of CD5 expression on leukaemic T cells, and may help in understanding the molecular mechanism of CD5 down-regulation.

TLR4 supports the expansion of FasL+CD5+CD1dhi regulatory B cells, which decreases in contact hypersensitivity

Certain B cells termed as “regulatory B cells” (Bregs) can suppress the ongoing immune responses and a splenic CD5+CD1dhi Breg subset identified earlier was shown to exert its regulatory functions through secretion of IL-10. Though FasL expression is an alternative mechanism of immune suppression used by B cells, little is known about the FasL expressing CD5+CD1dhi Bregs. In this study, we isolated splenocytes or splenic CD19+ B cells and compared the efficiency of toll-like receptor(TLR)4 ligand (lipopolysaccharide) with TLR9 ligand (CpG), anti-CD40 and TLR9 ligand (CpG) plus anti-CD40 on the FasL expression of splenic CD5+CD1dhi Bregs by flow cytometry. FasL expression in CD5+CD1dhi B cells was rapidly increased after TLR4 ligation. Intriguingly, anti-CD40 and CpG plus anti-CD40 combinations failed to stimulate FasL expression in CD5+CD1dhi B cells although the IL-10 production was up-regulated in this subset. In addition, LPS and other B10-cell inducers increased the expression of surface molecules like CD86 and CD25, which are correlated to the regulatory functions of B cells. Furthermore, NF-κB and NF-AT inhibitors decreased the TLR4-activated FasL expression in CD5+CD1dhi B cells. Then we sorted splenic CD5+CD1dhi Bregs using flow cytometry and found that TLR4-activated CD5+CD1dhi Bregs suppressed the proliferation of CFSE-labeled CD4+ T cells in vitro, which was partly blocked by anti-FasL antibody. In oxazolone-sensitized mice having contact hypersensitivity, FasL expression in splenic CD5+CD1dhi B cells was decreased compared to the control group after TLR4 ligation. Our findings suggest that the regulatory function of CD5+CD1dhi B cells could be partly mediated by Fas-FasL pathway and this FasL expressing CD5+CD1dhi Bregs might participate in the regulation of inflammatory diseases.

CD5-mediated inhibition of TCR signaling proceeds normally in the absence of SHP-1.

The CD5 transmembrane glycoprotein functions as a co-receptor in the signaling pathway linking T-cell antigen receptor (TCR) engagement to activation and differentiation. Although CD5 effects on TCR signaling have been shown to be primarily inhibitory, the underlying mechanisms remain unclear. In view of recent data revealing the ability of CD5 to associate with the SHP-1 tyrosine phosphatase, a protein that also downregulates TCR signaling, we examined the role of SHP-1 in modulating CD5 function using thymocytes from SHP-1-deficient viable motheaten (mev) mice. The results revealed the association of SHP-1 with CD5 to be markedly increased following TCR stimulation and indicated that this interaction was enhanced by and was dependent on CD5 tyrosine phosphorylation. However, there was no difference of the tyrosine phosphorylation status of CD5 between resting and TCR-stimulated cells in SHP-1-deficient compared to wild-type thymocytes. Lack of SHP-1 activity did not affect the levels of CD5 surface expression, CD5 co-immunoprecipitable tyrosine phosphatase activity and intracellular calcium increase following co-crosslinking of the TCR and CD5. Similarly, an analysis of T-cell thymocyte populations in mev mice expressing an H-Y transgene as well as a construct mediating T-cell restricted CD5 overexpression, revealed that the reduction in the positive selection conferred by CD5 overexpression was unaffected by SHP-1 deficiency. CD5 is not a SHP-1 substrate and SHP-1 is not required for and possibly not involved in the CD5-mediated modulation of TCR signaling.

Expression of Activated Molecules on CD5+ b Cells in Autoimmune Hemolytic Anemia

Objective To detect the percentage of CD5+ B cells in peripheral blood (PB) of patients with autoimmune hemolytic anemia (AIHA) /Evans syndrome and the expression of active molecules on CD5+ B cells.Methods The expressions of CD80, CD86, CD69 and HLA-DR on CD5+ B cells in PB of 25 cases with AIHA/Evans syndrome, (11 newly diagnosed, 14 remission) and 14 normal controls were detected by flow cytometry.Results (1) The percentage and the quantity of CD19+ B cells in newly diagnosed patients were [(22.78±19.77)%, (34.47±22.88)×107/L] respectively, which were obviously higher than those of remission patients [(6.80±5.47)%,(10.09±7.69)×107/L] and normal controls [(7.76±2.6)%,(10.03±3.31)×107/L](p<0.05), but there was no significant difference between the latter two groups. (2)The percentage of CD5+ B cells in B cells of untreated patients was [(27.44±18.43) %], which was higher than that of normal controls [(13.49±6.95) %, P=0.008]. The percentage of CD5- B cells of untreated patients and normal controls were [(72.56±18.43) %], [(83.92±11.46) %] and there was no significant difference. (3)CD80 on CD5+ B cells of untreated patients was [(46.04±26.93)%], which was obviously higher than that of remission patients [(8.82±8.78)%,P=0.003] and normal controls [(6.27±4.87)%,P=0.002], the latter two groups had no significant difference. There was no significant difference of CD80 on CD5- B cells among the three groups. CD86 on CD5+ B cells of untreated patients was [(37.37±24.18)%], which was significantly higher than that of remission patients [(16.53±10.31)%,P=0.004] and normal controls [(14.90±9.62)%,P=0.029], the latter two groups had no significant difference. But CD86 on CD5- B cells are similar in the three groups and there was no difference. CD69 on CD5+ B cells of newly diagnosed patients was (median: 5.77%), which was higher than that of remission patients (3.34%) and normal controls(4.01%), but without any significant difference within three groups. CD69 on CD5- B cells showed no significant difference among three groups. HLA-DR on CD5+ B cells and CD5- B cells showed no significantly difference within three groups. (4)The expression of CD80[(46.04±26.93)%] and CD86[(37.37±24.18)%] on CD5+ B cells were higher than those on CD5- B cells [(22.57±10.54)%,P=0.016], [(17.92±16.27)%,P=0.006]. The expression of CD69 (median: 5.77%) on CD5+ B cells was higher than that of on CD5- B cells (median: 1.20%), but without significant difference. The expression of HLA-DR on CD5+ B cells and CD5- B cells had no significant difference. (5)The expression of CD80 on CD5+ B cells [(8.82±8.78) %] was lower than that of on CD5- B cells [(28.68±18.59) %, P=0.001]. The expression of CD86, CD69 and HLA-DR on CD5+ B cells and CD5- B cells showed no significant difference. (6)The expression of CD80 on CD5+ B cells [(6.27±4.87)%] was lower than that of on CD5- B cells [(27.54±9.42)%,P<0.05]. The expression of CD86ACD69 and HLA-DR on CD5+ B cells and CD5- B cells had no significant difference.Conclusions The percentage and quantity of B lymphocytes in PB of AIHA/Evans syndromes patients increased. CD5+ B lymphocytes are mainly cells and CD80 and CD86 on CD5+ B cells went up. The activated molecules on cell surface may be the basis of the different function of CD5+ and CD5- B lymphocytes. DisclosuresNo relevant conflicts of interest to declare.

Impaired Function of CD5+CD19+CD1dhi B10 Cells on IgE Secretion in an Atopic Dermatitis-Like Mouse Model.

Atopic dermatitis (AD) is a chronic inflammatory pruritic skin disease in which the pathogenic mechanism is complicated and not completely understood. Reports on the role of regulated cells in AD have recently evolved to regulate B cells, which may play a role in allergic inflammation as well. In the present study, we examined the frequency and regulatory function of CD5+CD19+CD1dhi B10 cells in an AD-like mouse model. Our results showed that the percentage of CD5+CD19+CD1dhi B10 cells increased while the frequency of IL-10-producing B cells in CD19+B cells decreased in the mice of AD group. Moreover, no difference in the percentage of B10pro+B10 cells was observed between the AD and control groups. Strikingly, B10 cells from control mice effectively inhibited IgE secretion, whereas the suppressive function of B10 cells from the AD mice was significantly decreased, which was similar to that observed in the group without B10. Altogether, these results suggest that the number of IL-10-producing B cells decreased in the AD group and these cells showed a defective regulatory function on IgE secretion.

LPS up-regulates FasL expression in Breg population in mice (IRM12P.643)

Abstract Regulatory B cell plays important role in negative immune regulation, it can exert the inhibitory functions partly by the secretion of IL-10. FasL is also considered to be associated with the immune regulatory function of B cells. Here, we first observed the expression of FasL in CD5+CD1dhi Breg population as well as other B cell subsets after LPS stimulation.In this study, splenocytes were isolated from C57/BL6 wild-type mice and cultured with LPS for 24-48 hours to activate Breg. Results showed that the expression of FasL in CD5+CD1dhi B cell subset is much higher than CD19+CD5+CD1dlow and CD19+CD5neg B cell subset. The lowest FasL expression was seen in CD19+CD5neg B cell subset. This is consistent with the expression of IL-10 in corresponding B cell subsets. In addition, studies showed that the expression of CD25 molecules in CD19+CD5+CD1dhi Breg was significantly higher than other two B cell subsets after stimulating by LPS for 24 hours. CD86 molecule was highly expressed in all these three B cell subsets, and it is higher in CD19+CD5+CD1dhi Breg compared with other B subsets. In contact hypersensitivity model, the expression of FasL in CD19+CD5+CD1dhi Breg after LPS activation showed significant difference in comparison with control group.These results suggested that FasL might also contribute to the inhibitory function of CD5+CD1dhi Breg population after LPS stimulation and thus participate in the regulation of some inflammatory immune diseases.

CD5 as a Target for Immune-Based Therapies.

CD5 was one of the first surface receptors described for mouse and human T lymphocytes. Since then, it has been found to be highly expressed by regulatory T cells and a subpopulation of regulatory B cells, to be physically associated with the T- and B-cell antigen receptors, to negatively modulate TCR- and BCR-mediated signals, and to bind certain pathogen-associated molecular patterns. These findings position CD5 as an attractive target for developing immunotherapies aimed at either boosting or dampening ongoing immune responses. Here the available data on the function of CD5 and its involvement in the regulation of immune responses in health and disease are reviewed, as well as the evidence for and future challenges in developing therapeutic strategies aimed at targeting CD5 for autoimmune diseases, cancer, and infections.

Dielectric function of the ferromagnetic semiconductor CdMnCrTe studied by using spectroscopic ellipsometry

We describe the pseudo-dielectric function of Cd1−x−yMnxCryTe ferromagnetic semiconductor alloys by using spectroscopic ellipsometry in the 1.0 ~ 6.0 eV spectral range at room temperature. The ellipsometry data include structures that can be attributed to the effects of Cr concentration on the E0, E1, E1 + Δ1, and E2 critical points. Critical-point (CP) parameters were obtained by fitting standard critical point (SCP) model line shapes to the numerically-calculated second- energy derivatives of e(ω) = e1(ω) + ie2(ω). The E0, E1, E1 + Δ1, and E2 energies decreased with Cr content y; this phenomenon is related to the hybridization of the valence and the conduction bands in CdTe with the 3d states of Mn and Cr.