Percentage Of Programmed Death-1 Research Articles

Changes and correlations of T-cell coinhibitory molecule programmed death-1 and interferon-γ in pediatric immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by abnormalities of T cells subsets. Programmed death-1 (PD-1) is a co-signaling inhibitory molecule in T cells that is involved in many autoimmune diseases. Here we aimed to measure changes in PD-1 expression and serum interferon-γ (IFN-γ) levels before and 1 month after treatment in pediatric patients with newly diagnosed ITP. We measured PD-1+ CD4+ T cells percentages using flow cytometry and the serum IFN-γ levels by enzyme-linked immunosorbent assay in 40 pediatric patients with ITP and 20 healthy controls. Compared with healthy controls, the PD-1+ CD4+ T cells percentages and serum IFN-γ levels were significantly higher in ITP patients before and 1 month after therapy. A correlation study revealed that PD-1+ CD4+ T cells percentage was negatively associated with platelet count and positively associated with IFN-γ level in patients with ITP. Furthermore, serum IFN-γ levels were significantly decreased in patients after treatment, but no significant change was detected in the percentage of PD-1+ CD4+ T cells before or 1 month after therapy. PD-1+ CD4+ T cells expression and IFN-γ levels were increased in patients with ITP. These preliminary data suggest a potential role of PD-1+ CD4+ T cells as mediators of ITP. We also found a correlation between PD-1+ CD4+ T cells and both platelet counts and IFN-γ levels. These findings suggest a potential role of PD-1+ CD4+ T cells and IFN-γ in the pathogenesis of ITP. Further studies investigating PD-1 expression in different T-cell subsets, serum IFN-γ concentrations, and antiplatelet antibodies levels over a longer duration after therapy initiation could delineate the precise role of PD-1 in ITP pathogenesis. Consequently, novel nontraditional therapeutic strategies for ITP patients may become available.

The role of spatial interplay patterns between PD-L1-positive tumor cell and T cell in recurrence of locally advanced non-small cell lung cancer.

To explore the relationship between the spatial interaction of programmed death-ligand 1(PD-L1)-positive tumor cell and T cell with specific functions and the recurrence of non-small cell lung cancer (NSCLC) and optimize prognostic stratification. This study retrospectively included 104 patients with locally advanced NSCLC who underwent radical surgery. Tissue microarrays were constructed including tumor center (TC) and invasion margin (IM), and CK/CD4/CD8/PD-L1/programmed death-1 (PD-1) was labeled using multiplex immunofluorescence to decipher the counts and spatial distribution of tumor cells and T cells. The immune microenvironment and recurrence stratification were characterized using the Mann-Whitney U test and Cox proportional hazards model. Compared with the IM, the proportion of tumor cells (especially PD-L1+) was increased in the TC, while T cells (especially PD-1+) were decreased. An increase in TC PD-1+ CD8 T cells promoted relapse (HR = 2.183), while PD-L1+ tumor cells alone or in combination with T cells had no predictive value for relapse. In addition, in both TC and IM, CD8 were on average closer to PD-L1+ tumor cells than CD4, especially exhausted CD8. The effective density and percentage of PD-1+ CD4 T cells interacting with PD-L1+ tumor cells in the IM were both associated with recurrence, and the HRs increased sequentially (HRs were 2.809 and 4.063, respectively). Patients with low PD-1+CD4 count combined high PD-1+CD4 effective density showed significantly poorer RFS compared to those with high PD-1+CD4 count combined low PD-1+CD4 effective density, in both the TC and IM regions (HRs were 5.810 and 8.709, respectively). Assessing the relative spatial proximity of PD-1/PD-L1 contributes to a deeper understanding of tumor immune escape and generates prognostic information in locally advanced NSCLC patients.

OX40 enhances T cell immune response to PD-1 blockade therapy in non-small cell lung cancer

Immune-checkpoint blockade is widely studied for cancer therapy. Although the co-inhibitory receptor Programmed death-1(PD-1) blockade benefits some non-small cell lung cancer (NSCLC) patients, a large portion of NSCLC patients still fail to respond to this immunotherapy, and the underlying mechanism is unclear. Thus, a synergistic therapy to enhance the effect of PD-1 is urgently needed to improve the poor outcome of NSCLC patients. Here, we demonstrated that effector memory T cells were increased and T cell response became stronger in PD-1 immunotherapy responders (n = 20) but not in non-responders (n = 10). The expression of co-stimulatory receptor OX40 was upregulated on T cells following PD-1 immunotherapy and was positively associated with the percentage of PD-1+T cells and the responsiveness of T cells. Combination treatment of antagonistic anti-PD-1 and agonistic anti-OX40 antibodies (Abs) promoted the proliferation and cytokines production of T cells from PBMCs of non-responders ex vivo. Consistently, anti-PD-1 and anti-OX40 therapy synergistically augmented T cell response in an in vivo mouse lung cancer model. Our study confirmed the antitumor effects of anti-PD-1/OX40 combination in lung cancer patients as well as in the murine lung cancer model, and the results provide a rationale for clinical trials evaluating the therapeutic effect of this combination of antibodies for NSCLC immunotherapy.

The prognostic role of the programmed death-1 expression on T lymphocytes in septic patients

Objective: To investigate the value of programmed death-1（PD-1） expression on the T lymphocytes for the prognosis of septic patients. Methods: From September 2017 to May 2019, septic patients were included in Department of Intensive Care Unit at 6 hospitals. The PD-1 expression on T cells were measured by flow cytometry. Logistic regression was conducted to analyze independent risk factors related to death within 28 days，and receiver operating characteristic curve(ROC) was conducted to evaluate the prognostic value of PD-1 expression on T cells in septic patients. Results: A total of 64 septic patients were enrolled to this study，including 32 survivors and 32 deaths. The PD-1 expression on T cells in the death group was significantly higher than that in the surviving group (P<0.05). Correlation analysis showed that the percentages of PD-1+/CD3+T cells and PD-1+/CD8+T cells were positively correlated with procalciton in (r=0.313, P =0.015；r=0.375, P=0.003), logistic regression analysis showed that the percentages of PD-1+/CD3+，PD-1+/CD4+，PD-1+/CD8+T cells were independent risk factors for the death of sepsis patients. The percentage of PD-1+/CD3+T cell was 3.63%, with AUC 0.842, sensitivity to predict the mortality 96.43% and specificity 59.38%, (P<0.000 1). The percentage of PD-1+/CD4+T cell was 4.65%, with AUC 0.847, sensitivity 96.43%, specificity 62.50%，(P<0.000 1). The percentage of PD-1+/CD8+T cell was 3.91%, with AUC 0.771, sensitivity 64.29%, specificity 81.25%，(P=0.000 3). Conclusions: The T cell PD-1 expression is an independent risk factor to predict the 28-day mortality in septic patients. Combining the proportions of PD-1+/CD3+, PD-1+/CD4+and PD-1+/CD8+T cells may further enhance the predictive value for death.

Intraoperative Flurbiprofen Treatment Alters Immune Checkpoint Expression in Patients Undergoing Elective Thoracoscopic Resection of Lung Cancer

Objectives: This study aimed to determine the effect of intraoperative administration of flurbiprofen on postoperative levels of programmed death 1 (PD-1) in patients undergoing thoracoscopic surgery. Materials and Methods: In this prospective double-blind trial, patients were randomized to receive intralipid (control group, n = 34, 0.1 mL/kg, i.v.) or flurbiprofen axetil (flurbiprofen group, n = 34, 50 mg, i.v.) before induction of anesthesia. PD-1 levels on T cell subsets, inflammation, and immune markers in peripheral blood were examined before the induction of anesthesia (T₀) and 24 h (T₁), 72 h (T₂), and 1 week (T₃) after surgery. A linear mixed model was used to determine whether the changes from baseline values (T₀) between groups were significantly different. Results: The increases in the percentage of PD-1⁽⁺⁾CD8⁽⁺⁾ T cells observed at T₁ and T₂ in the control group were higher than those in the flurbiprofen group (T₁: 12.91 ± 1.65 vs. 7.86 ± 5.71%, p = 0.031; T₂: 11.54 ± 1.54 vs. 8.75 ± 1.73%, p = 0.004), whereas no differences were observed in the changes in the percentage of PD-1⁽⁺⁾CD4⁽⁺⁾ T cells at T₁ and T₂ between the groups. Moreover, extensive changes in the percentage of lymphocyte subsets and inflammatory marker concentrations were observed at T₁ and T₂ after surgery and flurbiprofen attenuated most of these changes. Conclusions: Perioperative administration of flurbiprofen attenuated the postoperative increase in PD-1 levels on CD8⁽⁺⁾ T cells up to 72 h after surgery, but not after this duration. The clinical relevance of changes in PD-1 levels to long-term surgical outcome remains unknown.

The Clinical Significance of Programmed Death-1, Regulatory T Cells and Myeloid Derived Suppressor Cells in Patients with Nontuberculous Mycobacteria-Lung Disease.

Background: Increasing expression of programmed death-1 (PD-1) in patients with nontuberculous mycobacteria lung disease (NTM-LD) has been reported, but its role in clinical characteristics and outcomes remains unclear. Methods: We enrolled 96 participants, including 46 with Mycobacterium avium complex (MAC)-LD, 23 with M. abscessus (MAB)-LD, and 27 controls. We measured expressions of PD-1, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and regulatory T (Treg) cells on CD4+ lymphocytes and myeloid-derived suppressor cells (MDSCs) and analyzed their association with clinical features and radiographic outcomes. Results: The percentage of PD-1 on CD4+(PD-1+CD4+) lymphocytes and MDSCs were higher in the MAC-LD group than the controls. There were no intergroup differences regarding CTLA-4+CD4+ lymphocytes. Higher PD-1+CD4+ lymphocytes were found in M. intracellulare- and M. avium-LD than in other MAC-LD. Positive sputum acid-fast stains and fibrocavitary radiographic lesions were correlated with elevated PD-1+CD4+ lymphocytes and Treg cells. The percentage of PD-1+CD4+ lymphocytes at the initial and 2 months of follow-up significantly predicted subsequent radiographic progression. Conclusion: As markers of immune tolerance, PD-1+CD4+ lymphocytes and MDSCs were higher in MAC-LD patients. The levels of PD-1+CD4+ and Treg cells were correlated with high mycobacteria bacilli burden in NTM-LD. Monitoring the expressions of PD-1+CD4+ lymphocytes may predict radiographic progression.

Decreased T helper 17 cells in tuberculosis is associated with increased percentages of programmed death ligand 1, T helper 2 and regulatory T cells

BackgroundTuberculosis (TB) is one of the most common infectious diseases worldwide. During active tuberculosis, T helper (Th) 17 cells are decreased, however the association with inhibitory immune regulation is unclear.MethodsWe enrolled 27 patients with TB and 20 age- and sex-matched controls and studies their lymphocyte status. Peripheral blood lymphocytes were isolated and programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) were measured on Th17 cells by using flow cytometry after the cells were stimulated with phorbol 12-myristate 13-acetate and ionomycin for 6 h. In addition, Th2 and regulatory T cells were measured and analyzed.ResultsThe TB group had lower levels of Th17 cells but higher levels of Th2 and Treg cells than the controls. In Th17 cells, the percentage of PD-L1 was higher in the TB group than that in the controls. In Th2 and Treg cells, the percentage of cytotoxic T-lymphocyte associated protein 4 (CTLA-4) was lower in the TB group and PD-1 was higher in Treg cells in the TB group. In the patients with extra-pulmonary TB, levels of Th1, Th2 and T17 cells were lower than those with pulmonary TB. The percentage of PD-1 on Th1 lymphocytes positively correlated with radiographic score.ConclusionsLower level of Th17 in TB patients may be associated with increased percentage of PD-L1 and increasing levels of Th2 and Treg cells which influenced by CTLA-4.

The Expression of Programmed Death-1 on CD4+ and CD8+ T Lymphocytes in Patients with Type 2 Diabetes and Severe Sepsis

ObjectiveTo investigate the expression of Programmed death-1 (PD-1) on T lymphocytes in patients with type 2 diabetes mellitus (T2DM) and severe sepsis, we determined PD-1 expression on CD4+ and CD8+ T lymphocytes of patients with T2DM, severe sepsis, and T2DM combined with severe sepsis.Research Design and MethodsThis prospective and observational study included 50 healthy controls, 80 cases of T2DM without infection (T2DM group), 88 cases of severe sepsis without T2DM (SS group), and 77 cases of severe sepsis combined with T2DM (SS+T2DM group). Expression of peripheral blood PD-1+ CD4+ T cells and PD-1+ CD8+ T cells were compared between these 4 groups. Then, 28-day survival of the SS and SS+T2DM patients was assessed, and the expression of PD-1 on T cells was also compared between survivors and non-survivors.ResultsPercentages of PD-1+ CD4+ T cells and PD-1+ CD8+ T cells were higher in the T2DM group than in the healthy control group, and were highest in the SS and SS+T2DM groups. However, the expression of PD-1 on T cells and the mortality showed no significant difference between the SS and SS+T2DM groups. The expression of PD-1 on T cells was higher in non-survivors than survivors, but within the survivor group or non-survivor group, no difference can be detected between those with T2DM and those without T2DM.ConclusionThe expression of PD-1 on T cells was increased in both T2DM and severe septic patients, but combining T2DM did not cause a further increase on the PD-1 expression in patients with severe sepsis.

Cooperation of PD-1 and LAG-3 Contributes to T-Cell Exhaustion in Anaplasma marginale-Infected Cattle

The CD4(+) T-cell response is central for the control of Anaplasma marginale infection in cattle. However, the infection induces a functional exhaustion of antigen-specific CD4(+) T cells in cattle immunized with A. marginale outer membrane proteins or purified outer membranes (OMs), which presumably facilitates the persistence of this rickettsia. In the present study, we hypothesize that T-cell exhaustion following infection is induced by the upregulation of immunoinhibitory receptors on T cells, such as programmed death 1 (PD-1) and lymphocyte activation gene 3 (LAG-3). OM-specific T-cell responses and the kinetics of PD-1-positive (PD-1(+)) LAG-3(+) exhausted T cells were monitored in A. marginale-challenged cattle previously immunized with OMs. Consistent with data from previous studies, OM-specific proliferation of peripheral blood mononuclear cells (PBMCs) and interferon gamma (IFN-γ) production were significantly suppressed in challenged animals by 5 weeks postinfection (wpi). In addition, bacteremia and anemia also peaked in these animals at 5 wpi. Flow cytometric analysis revealed that the percentage of PD-1(+) LAG-3(+) T cells in the CD4(+), CD8(+), and γδ T-cell populations gradually increased and also peaked at 5 wpi. A large increase in the percentage of LAG-3(+) γδ T cells was also observed. Importantly, in vitro, the combined blockade of the PD-1 and LAG-3 pathways partially restored OM-specific PBMC proliferation and IFN-γ production at 5 wpi. Taken together, these results indicate that coexpression of PD-1 and LAG-3 on T cells contributes to the rapid exhaustion of A. marginale-specific T cells following infection and that these immunoinhibitory receptors regulate T-cell responses during bovine anaplasmosis.

Expression of programmed death 1 is correlated with progression of osteosarcoma.

Accumulating bodies of evidence indicate that immune dysregulation plays a key role in the development of osteosarcoma (OS). Programmed death 1 (PD-1) is a surface receptor expressed on activated and exhausted T cells, which mediate T-cell inhibition upon binding with its ligand. Researches on PD-1 and OS remain extremely limited. Here, we investigated whether PD-1 could be involved in the development of OS. Expression of PD-1 was measured by flow cytometry on peripheral CD4+ and CD8+ T cells from 56 OS cases and 42 healthy controls. Data revealed that percentages of PD-1 were significantly upregulated on both peripheral CD4+ and CD8+ T cells from OS patients (p<0.001 and p<0.001, respectively). Patients with different tumor locations did not present obvious variations in PD-1 level. However, patients with metastasis showed significantly higher level of PD-1 on CD4+ T cells than those without metastasis (p<0.001). Furthermore, PD-1 expression on CD4+ T cells started to increase in stage III, whereas PD-1 expression on CD8+ T cells started to increase in stage II. In addition, patients with pathological fracture were observed to have elevated PD-1 on both CD4+ and CD8+ T cells. These data suggest that PD-1 is involved in the pathogenesis of OS, especially in the progression of disease.

Exhaustion of bacteria-specific CD4 T cells and microbial translocation in common variable immunodeficiency disorders.

In the present study, we have investigated the functional profile of CD4 T cells from patients with common variable immunodeficiency (CVID), including production of cytokines and proliferation in response to bacteria and virus-derived antigens. We show that the functional impairment of CD4 T cells, including the reduced capacity to proliferate and to produce IFN-γ and IL-2, was restricted to bacteria-specific and not virus-specific CD4 T cells. High levels of endotoxins were found in the plasma of patients with CVID, suggesting that CD4 T cell dysfunction might be caused by bacterial translocation. Of note, endotoxemia was associated with significantly higher expression of programmed death 1 (PD-1) on CD4 T cells. The blockade of the PD-1-PD-L1/2 axis in vitro restored CD4 T cell proliferation capacity, thus indicating that PD-1 signaling negatively regulates CD4 T cell functions. Finally, we showed that intravenous immunoglobulin G (IVIG) treatment significantly reduced endotoxemia and the percentage of PD-1(+) CD4 T cells, and restored bacteria-specific CD4 T cell cytokine production and proliferation. In conclusion, the present study demonstrates that the CD4 T cell exhaustion and functional impairment observed in CVID patients is associated with bacterial translocation and that IVIG treatment resolves bacterial translocation and restores CD4 T cell functions.

The upregulation of programmed death 1 on peripheral blood T cells of glioma is correlated with disease progression

Glioma is the most common primary brain tumor. Programmed death 1 (PD-1) is a surface receptor expressed on activated and exhausted T cells, which mediate T cell inhibition upon binding with its ligand. In the current study, we investigated the expression of PD-1 on peripheral CD4+ and CD8+ T cells in glioma patients. Percentage of PD-1+ cells was measured by flow cytometry in 86 glioma cases and 62 healthy controls. Results showed that PD-1 expression was significantly increased in both peripheral CD4+ and CD8+ T cells in glioma (p < 0.001 and p < 0.001, respectively). When comparing PD-1 level in glioma patients with different histological types, patients with astrocytomas revealed clearly higher proportion of PD-1 on CD4+ T cells than those with oligodendrogliomas (p < 0.001), ependymomas (p < 0.001), or pilocytic astrocytomas (p < 0.001). Also, patients with the highest tumor grade (IV) demonstrated the most elevated expression of PD-1 on both CD4+ and CD8+ T cells. Interestingly, cases with tumor grade III and IV had downregulated PD-1 level on peripheral CD4+ T cells after surgery, whereas only grade IV patients showed decreased proportion of PD-1 on CD8+ T cells after treatment. In addition, no correlation between PD-1 expression and progression to secondary glioblastoma was observed. These data suggested PD-1 may act as a positive regulator in the pathogenesis and progression of glioma.

Higher Frequency of Peripheral Blood Interleukin 21 Positive Follicular Helper T Cells in Patients with Ankylosing Spondylitis

The role of follicular Th (TFH) cells remains unclear in the pathogenesis of ankylosing spondylitis (AS). Our study examined the frequency of different subsets of circulating CXCR5+CD4+ T cells in patients with AS before and after receiving therapy. Percentages of peripheral blood inducible costimulator (ICOS)+, programmed death 1 (PD-1)+, and interleukin 21 (IL-21)+ CXCR5+CD4+ T cells in 26 patients with AS and 12 healthy controls (HC) were examined by flow cytometry, and the disease activity of individual patients was measured by Bath AS Disease Activity Index (BASDAI). The concentrations of serum IL-21, IgG, IgA, IgM, and C-reactive protein (CRP) were examined and the values of erythrocyte sedimentation rate (ESR) were measured. The potential association among these measures was analyzed. In comparison with that in HC, significantly increased percentages of CXCR5+CD4+, CXCR5+CD4+PD-1+, and CXCR5+CD4+IL-21+, but not CXCR5+CD4+ICOS+ and PD-1+ICOS+CXCR5+CD4+ T cells, and elevated concentrations of serum IL-21 were detected in patients with AS (p = 0.001, p = 0.012, p < 0.001, p = 0.233, p = 0.216, p < 0.001, respectively). Treatment with meloxicam, thalidomide, and etanercept for 1 month significantly reduced percentages of IL-21+CXCR5+CD4+ T cells and concentrations of serum IL-21 (p < 0.001, p < 0.001, respectively), accompanied by significantly minimized disease activity in drug responders, but not in the drug nonresponders. Further, percentages of IL-21+CXCR5+CD4+ T cells were positively correlated with BASDAI in patients (r = 0.6, p = 0.0012) and in the drug-responders 1 month after treatment (r = 0.68, p = 0.005), while the percentages of PD-1+CXCR5+CD4+ T cells were negatively correlated with BASDAI (r = -0.58, p = 0.0018). These data suggest that IL-21+CXCR5+CD4+ T cells may be associated with development of AS and that the frequency of IL-21+CXCR5+CD4+ T cells may be a biomarker for evaluation of disease activity and drug responses in patients with AS, particularly in drug-responding patients.

Expression of Programmed Death-1 (PD-1) on CD4+ and CD8+ T cells in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by chronic inflammatory process that targets the synovial lining of diarthrodial joints. Programmed death 1 (PD-1) plays a key role in the negative regulation of the immune response. In the current study, we investigated the expression of PD-1 on peripheral CD4+ and CD8+ T cells in RA patients. Percentage of PD-1+ cells was measured by flow cytometry in 82 RA cases and 90 healthy controls. Results showed that PD-1 expression was significantly decreased in both peripheral CD4+ and CD8+ T cells in RA (p = 0.002 and p < 0.001, respectively). Similarly, serum levels of soluble PD-1 were also downregulated in RA cases. When comparing PD-1 level in RA patients with different clinical parameters, patients with positive C-reactive protein (CRP) revealed lower proportion of PD-1 on CD4+ and CD8+ T cells than those with negative CRP. Also, disease activity score of RA patients was inversely correlated with PD-1 expression on peripheral CD4+ and CD8+ T cells. These data suggested that PD-1 may act as a negative regulator in the pathogenesis and progression of RA.

T Cell Exhaustion Contributes to Immune Evasion in Chronic Lymphocytic Leukaemia

Abstract 1773T cell exhaustion is a state of T cell dysfunction in response to chronic antigen exposure, marked by impaired effector function and the continued expression of inhibitory receptors such as Programmed Death 1 (PD-1) (Wherry EJ. Nat Immunol. 2011 Jun;12(6):492–9.). Because tumour growth in chronic lymphocytic leukaemia (CLL) occurs over a long period of time, we hypothesized that the continued exposure of T cells to a CLL-derived antigen could also lead to a state of T cell exhaustion. We therefore investigated whether T cell exhaustion is induced in CLL by using the Eμ-TCL1 transgenic (tcl1tg) tumour transfer mouse model for this disease (Hofbauer JP, et al. Leukemia. 2011 Sep;25(9):1452-8) and by analyzing primary samples from CLL patients. We found that the number of PD-1+ T cells was increased in both CD4+ and CD8+ populations and in all lymphoid compartments examined of the Eμ-TCL1 transgenic (tcl1tg) tumour recipient mice, but not in recipient mice receiving wildtype (WT) splenocytes showing that leukemic mice have an increased number of T cells displaying an exhausted phenotype that is induced by the presence of CLL cells. We next assessed the expression of the ligands for PD-1 on the surface of murine CLL cells. Peripheral CLL tumour cells showed only a modest increase in PD-L1 expression as compared to WT B cells. However, lymph node and spleen residing tumour cells showed a marked increase in PD-L1 expression, which suggests a microenvironment-induced upregulation of PD-L1 on tumour cells, e.g. by their close contact to accessory cells.To validate our results on primary human CLL samples, we collected peripheral blood from 89 unselected CLL patients and 18 healthy donors and observed an increase in surface expression of PD-1 on the CD4+ and CD8+ T cell populations. While the percentage of PD-1+ CD4+ T cells in chemonaive patients was comparable to healthy donors, chemotherapy drastically increased the number of PD-1-expressing CD4+ T cells (63.81% ±19.75 vs 35.70% ±19.22; p<.001). In contrast, treatment apparently had little impact on the PD-1+ CD8+ population, indicating that PD1 induction on CD8+ T cells might be a more general CLL specific phenomenon. PD-1 expression in chemonaive patients did not correlate with the prognostic markers CD38, Zap-70 and IgVH mutations, however, it significantly correlated with Rai stage (CD4+: p<.001; CD8+: p=.003; spearman correlation). Our immune phenotyping analyses also included markers to distinguish between naïve, memory, and effector T cell subsets. We observed that PD-1 expressing T cells belong primarily to the memory compartment, characterized by the absence of CD45RA expression. PD-1 expression levels in T cells was independent from chronic human cytomegalovirus (HCMV) infection, indicating that increased PD-1+ T cell numbers in CLL do not simply reflect a higher incidence of HCMV infections, which has been described in this patient population.As we speculated that PD1/PDL1 pathway might be exploited by CLL to evade a T cell dependent cytotoxic attack, we next wanted to know whether blocking this pathway by recombinant PD1 (rPD1) or PD-L1 specific Fab fragments in vivo would lead to reinvigoration of CLL specific T cells reflected in CLL clearance. We found that inhibition of PD1/PD-L1 binding in vivo in the tcl1tg tumour transfer model led to a decrease in CLL load in the peripheral blood and in all analysed organs (lymph node, spleen, bone marrow, liver, lung) while in vitro treatment with rPD-1 or PD-L1 Fab fragment did not affect the viability of mouse tumour cells. Our results imply that in tumour bearing mice, a vast number of tumour-specific exhausted CTLs exist that can be immediately reactivated by PD1/PD-L1 blockage leading to cytolysis of the tumour, thereby representing a promising target for therapeutic intervention in CLL patients. Disclosures:No relevant conflicts of interest to declare.

Number of PD-1+/CD8+ Cells in Peripheral Blood of Patients with Lymphoma Reflects Tumor Burden, Lymphoma Subtype, Disease Phase and Is Significantly Higher Compared to Healthy Volunteers.

AbstractAbstract 2670 Background:Programmed death-1 (PD-1) and programmed death-1 ligand (PD-L) signaling pathways are involved in the functional impairment and “exhaustion” of cytotoxic CD8+ T cells in conditions such as chronic viral infection and in tumor immune evasion. The interaction of PD-1 with its ligand PD-L suppresses antitumor T cell function and indirectly stimulates Treg population. We investigated a hypothesis of whether examining PD-1 expression in peripheral T cells of patients with different lymphoma subtypes reflects tumor subtype or stage and compared results with healthy volunteers. Methods:Patients were assessed prior to their treatment or at the time of disease relapse or progression. We analyzed 5 patients with HL and 30 patients with NHL (T-cell n=6, diffuse large B-cell n=12, follicular lymphoma n=9, marginal zone lymphoma n=3). Twelve of the patients had relapsed or refractory diseases (B-NHL n=6, T-NHL n=2, HL n=4). Eleven patients (32%) had advanced (III/IV) disease stages. Data were compared with samples obtained from 12 healthy blood donors. Peripheral blood samples were stained with anti-CD3 FITC (Exbio), PD-1 (CD279) PE (BioLegend), anti-CD8 PerCP (Exbio), CD4 APC (Exbio), anti-CD25 FITC (BD), and anti-CD127 PE (BioLegend) using a lyse/no-wash protocol. Stained cells were acquired using the FACSCalibur cytometer (BD). Analysis of immunocompetent subpopulations was performed using the CellQuest Pro (BD) software. PD-1 (CD279) population was gated from CD3-positive T cells; minimal acquisition was designated as 10,000 CD3+ events. The percentage of PD-1+ cells within the live CD3+CD4+ and CD3+CD8+ populations was compared to isotype controls to establish baseline values. Absolute numbers were expressed as number of cells*10exp6 per liter. Population of Tregs was defined as CD4+/CD25int-hi / CD127low cells. Tregs were gated from CD4+ lymphocytes with minimal acquisition of 5,000 CD4+ cells. Results:Proportion of PD-1+/CD8+ of CD3+/CD8+ cells was significantly higher in patients with lymphoma than in healthy subjects: healthy volunteers (HV) 8.8%, B-NHL 16.0% (p=0.02), HL 21.8% (p<0.01), and T-NHL 30.8% (p<0.01). In absolute numbers of PD-1+/CD8+ cells, no significant difference was found when comparing healthy subjects and B-NHL: HV 0.23, B-NHL 0.56 (p=0.21), T-NHL 0.93 (p<0.01), and HL 1.51 (p<0.01). When analyzing the proportion of PD-1+/CD8+ cells according to disease phases, the highest numbers were found in patients with refractory/relapsed lymphoma as compared to patients with untreated disease and healthy subjects: HV 8.8%, untreated 14.6% (p=0.04), and relapsed 28.6% (p<0.01). Untreated patients had a significantly lower proportion of PD-1+/CD8+ cells than relapsed patients (p<0.01). Similar results were obtained with absolute numbers: HV 0.22, untreated 0.55 (p=0.03), and relapsed 1.24 (p=0.03). Untreated vs. relapsed patients p=0.05. Patients with limited disease stages had almost the same proportion of PD-1+/CD8+ lymphocytes compared to HV: HV 8.8%, limited stage 11% (p=0.21), and advanced stage 24.3% (p<0.01). In absolute numbers, HV had much less PD-1+/CD8+ cells in PB: HV 0.22, limited stage 0.49 (p<0.01), and advanced stage 0.97 (p<0.01). When analyzing the population of PD-1+/CD4+ cells, differences were only found in absolute numbers between HV (0.35) and HL (1.34; p<0.01), and between B-NHL (0.54) and HL (p=0.01). Regarding the population of Tregs, statistical differences were found between HV and B-NHL, HL or T-NHL in either relative or absolute numbers. On the other hand, there was a close correlation between absolute numbers of Tregs and PD-1+/CD4+ cells (p<0.01, correlation 0.73), and between Tregs and PD-1+/CD8+ cells (p<0.01, correlation 0.53). Conclusion:PD-1 expression in peripheral blood CD4+ and CD8+ cells is markedly different between lymphoma subtypes and compared with healthy subjects. The highest numbers of PD-1+/CD8+ are in patients with advanced lymphoma and at the time of disease relapse. This fact support the hypothesis that tumor clones actively switch effector CD8+ cells through the PD1L/PD-1 pathway into an immunotolerant state. PD-1 may be a potential marker of systemic immune dysregulation in lymphoma patients and further exploration of T cell subpopulations may define its role as a potential biomarker. Supported by grants: MSM 6198959205, LF-2012-007 and MZ ÈR IGA NT 11103. Disclosures:Prochazka:Roche: Travel grants Other.

Inverse correlation of programmed death 1 (PD-1) expression in T cells to the spinal radiologic changes in Taiwanese patients with ankylosing spondylitis

Programmed death 1 (PD-1) has been shown to be involved in the negative regulation of the immune response. However, the role of PD-1 in ankylosing spondylitis (AS) has not been studied. Therefore, we analyzed the expression of PD-1 in peripheral blood mononuclear cells (PBMC) from patients with AS. Twenty-three AS patients, 20 rheumatoid arthritis (RA) patients, and 25 normal healthy subjects were recruited. The percentage of the PBMC and PD-1 levels in these subjects were measured by flow cytometry. A higher percentage of CD4+ T cells was noted in AS patients than in healthy controls (37.53±1.65% vs. 31.55±0.92%, P<0.01), but a similar result was not observed with regard to CD3+ T lymphocytes, CD4+CD25 high+regulatory T cells, CD19+ B cells, and CD14+ and CD16+ monocytes/macrophages. PD-1 levels in PBMC were not significantly higher in AS patients than in RA patients or age- and gender-matched healthy controls and were also not correlated to the erythrocyte sedimentation rate, C-reactive protein, limitation of back flexion, and chest expansion in patients with AS. Of interest, the percentages of PD-1+CD3+ T cells and PD-1+CD4+ T cells were significantly lower in AS patients with higher modified Stokes Ankylosing Spondylitis Spinal Scores (mSASSS ≥30) than in those with lower mSASSS (<30; 0.07±0.04% vs. 0.42±0.14%, P<0.05; 0.06±0.03% vs. 0.40±0.14%, P<0.05, respectively). These results have suggested that the increased number of T helper cells lacking PD-1 may contribute to the spinal radiologic changes in AS patients.