Frequencies Of Cell Subsets Research Articles

Programmed Death-1+ T Cells and Regulatory T Cells Are Enriched in Tumor-Involved Lymph Nodes and Associated with Aggressive Features in Papillary Thyroid Cancer

Recurrent metastatic lymph node (LN) disease is common in patients with papillary thyroid cancer (PTC). Novel prognostic markers may be helpful in guiding a therapeutic approach. Our previous studies revealed that immune suppression is evident in PTC and associated with more severe disease. To characterize the immune response to metastatic PTC, we assessed CD4(+) T cell polarization in LN. In addition, we investigated the role of programmed death-1 (PD-1) and T cell exhaustion. Uninvolved (UILN) and tumor-involved lymph nodes (TILN) were sampled ex vivo by fine-needle biopsy. T cell subsets were identified by flow cytometry. In parallel, archived TILN specimens were characterized by immunofluorescence. The study was conducted at the University of Colorado Hospital. Data were collected on 94 LN from 19 patients with PTC undergoing neck dissection. T cell subset frequencies were compared in UILN and TILN and assessed for correlation with recurrent disease and extranodal invasion. Regulatory CD4(+) T cells (Treg) were enriched in TILN compared with UILN and further elevated in TILN from patients with recurrent disease. PD-1(+) T cells were present at high frequency in TILN and markedly enriched in TILN that showed evidence of extranodal invasion. In TILN, Treg frequency correlated with PD-1(+) T cell frequencies. Although PD-1(+) T cells produced interferon-γ, they failed to fully down-regulate CD27 and were not actively proliferating. Increased Treg and PD-1(+) T cell frequencies in LN may be indicative of aggressive recurrent PTC. Future prospective studies are necessary to determine the prognostic and therapeutic value of these findings in PTC.

Antiviral Treatment Alters the Frequency of Activating and Inhibitory Receptor-Expressing Natural Killer Cells in Chronic Hepatitis B Virus Infected Patients

Natural killer (NK) cells play a critical role in innate antiviral immunity, but little is known about the impact of antiviral therapy on the frequency of NK cell subsets. To this aim, we performed this longitudinal study to examine the dynamic changes of the frequency of different subsets of NK cells in CHB patients after initiation of tenofovir or adefovir therapy. We found that NK cell numbers and subset distribution differ between CHB patients and normal subjects; furthermore, the association was found between ALT level and CD158b+ NK cell in HBV patients. In tenofovir group, the frequency of NK cells increased during the treatment accompanied by downregulated expression of NKG2A and KIR2DL3. In adefovir group, NK cell numbers did not differ during the treatment, but also accompanied by downregulated expression of NKG2A and KIR2DL3. Our results demonstrate that treatment with tenofovir leads to viral load reduction, and correlated with NK cell frequencies in peripheral blood of chronic hepatitis B virus infection. In addition, treatments with both tenofovir and adefovir in chronic HBV infected patients induce a decrease of the frequency of inhibitory receptor+ NK cells, which may account for the partial restoration of the function of NK cells in peripheral blood following treatment.

The altered expression of inflammation-related microRNAs with microRNA-155 expression correlates with Th17 differentiation in patients with acute coronary syndrome

MicroRNAs (miRNAs) are a novel class of small, non-coding RNAs that play a significant role in both inflammatory and cardiovascular diseases. Immune cells, especially T helper (Th) cells, are critical in the development of atherosclerosis and the onset of acute coronary syndrome (ACS). To assess whether inflammation-related miRNAs (such as miR-155, 146a, 21, 125a-5p, 125b, 31) are involved in the imbalance of Th cell subsets in patients with ACS, we measured the expression of related miRNAs in patients with acute myocardial infarction (AMI), unstable angina (UA), stable angina (SA) and chest pain syndrome (CPS); analyzed the relationship between miRNA expression and the frequency of Th cell subsets; and observed the co-expression of miR-155 and IL-17A in peripheral blood mononuclear cells (PBMCs) of patients with ACS. The results showed that the expression of miR-155 in the PBMCs of patients with ACS was decreased by approximately 60%, while the expression of both miR-21 and miR-146a was increased by approximately twofold. The expression patterns of miRNAs in plasma correlated with those in PBMCs, except for miR-21, which was increased by approximately sixfold in the AMI group and showed no significant difference between the UA group and the CPS group. We also found that the expression of miR-155 inversely correlated with the frequency of Th17 cells (r=-0.896, P<0.01) and that miR-155 was co-expressed with IL-17A in patients with ACS. In conclusion, our study revealed the expression patterns of inflammation-related miRNAs in patients with ACS and found that miR-155 may be associated with Th17 cell differentiation.

Frequencies of FoxP3+ naïve T cells are related to both viral load and naïve T cell proliferation responses in HIV disease

HIV infection results in depletion and dysfunction of naïve CD4(+) T cells. The mechanisms underlying these deficiencies are not understood. We investigated the frequencies of CD4(+) naïve subsets in HIV disease as defined by expression of CD25 and/or FoxP3 and the relationship of these frequencies to naïve T cell proliferation function. We observed increased proportions of CD25(+)FoxP3(+) and CD25(+)FoxP3(-) cells and decreased proportions of CD25(-)FoxP3(-) cells within the naïve CD4(+) cell compartment from HIV-infected persons compared with findings in healthy donors. These perturbations were related to higher plasma HIV RNA levels but not with higher immune activation, as measured by the proportions of CD38(+) memory CD4(+) T cells. Naïve T cell proliferation responses to mitogen stimulation were inversely related to the frequencies and absolute numbers of FoxP3(+) naïve T cells. MDA, a marker of oxidative stress, and sCD14, a marker of monocyte activation and a surrogate for microbial translocation, were increased in serum samples from HIV(+) donors; however, neither marker was related to naïve T cell function in HIV(+) donors. These observations suggest that alterations in naïve T cell subset frequencies could contribute to naïve T cell dysfunction in HIV disease, but these alterations are not necessarily the result of chronic immune activation.

Immune Reconstitution in Recipients of Photodepleted HLA-Identical Sibling Donor Stem Cell Transplantations: T Cell Subset Frequencies Predict Outcome

We evaluated an exvivo photodepletion (PD) technique to selectively deplete graft-versus-host disease (GVHD) alloreacting T cells given to 24 human leukocyte antigen (HLA)-identical sibling stem cell transplantation (SCT) recipients. Donor lymphocytes were activated by 72-hour exposure to irradiated invitro expanded recipient T lymphocytes and pulsed with a TH9402 photosensitizer. Alloactivated T cells preferentially retaining the photosensitizer were eliminated by light exposure. The PD product showed an inverted CD4(+)/CD8(+) ratio with greatest depletion occurring in the CD4(+) naive and central memory populations. In contrast, the CD8(+) naive and effector cells were relatively conserved, reflecting the differential extrusion of TH9402 by T cell subsets. Cytomegalovirus reactive T cells were reduced in the PD product and in recipient blood 100 days after SCT when compared with contemporaneous HLA-identical sibling donor T cell-depleted SCT recipients. Although PD SCT recipients experienced similar absolute lymphocyte counts during the first 100 days after SCT, they achieved 100% donor T cell chimerism more rapidly and had higher CD8(+) naive T cell counts early after SCT. SCT recipients of PD products with the lowest CD4 central memory content had the highest risk of developing chronic GVHD (cGVHD) (P = .04) and a poorer survival (P = .03). Although the persistence of CD8(+) naive T cells may have contributed to important antileukemia responses resulting in a relatively low relapse rate, our findings emphasize the role of donor memory T cells and CD4 cells in establishing immune competence post-SCT. Although PD is associated with excellent outcomes in the haploidentical setting, the low frequency of alloactivations in HLA-matched pairs makes the PD approach used by our group for allodepletion in HLA-matched sibling transplantations an inefficient technique.

Decoupling age from cytomegalovirus-associated changes in the immune system (109.28)

Abstract CMV infection has been associated with premature immunosenescence and shorter lifespan. To date, no systems-wide analysis for decoupling age from CMV associated changes have been conducted. To address the differences between an immune system in naïve versus CMV infected humans and to decouple the age-related from CMV-related changes, we studied a comprehensive set of assays comprising serum cytokines, cell subset frequencies, whole genome gene expression and various stimulations of immune cells in 30 young and 60 older, CMV seropositive or seronegative individuals. For each measurement we performed a multiple regression analysis on all samples by age, CMV serostatus and the interaction between both variables (age × cmv). We found dramatic differences in multiple measurements of the immune system by age - mostly affecting T cell signaling responses, inflammatory cytokines and many immune-related genes, by CMV - which seems to preferentially modulate the CD4 and B cell compartments at different levels - or when both factors are present with changes mostly restricted to B cell functions. We present, for the first time, a systems immunology view of CMV- and age-associated changes in the immune system.

Natural Suppression of Human Immunodeficiency Virus Type 1 Replication Is Mediated by Transitional Memory CD8+T Cells

HIV replication is suppressed in vitro by a CD8(+) cell noncytotoxic antiviral response (CNAR). This activity directly correlates with an asymptomatic clinical state. The objective of this study was to identify the phenotype of CD8(+) cell subsets having strong CNAR activity. CD8(+) cell subset frequencies and CNAR levels were measured for human immunodeficiency virus (HIV)-uninfected individuals and three groups of HIV type 1 (HIV-1)-infected individuals: asymptomatic individuals with low-level viremia (vHIV), antiretroviral-drug-treated subjects with undetectable virus levels (TxHIV), and therapy-naïve aviremic elite controllers (EC). CD8(+) cells from the vHIV individuals exhibited the highest HIV-suppressing activity and had elevated frequencies of CD45RA(-) CD27(+) and PD-1(+) (CD279(+)) cells. Functional assessments of CD8(+) cells sorted into distinct subsets established that maximal CNAR activity was mediated by CD45RA(-) CCR7(-) CD27(+) and PD-1(+) CD8(+) cells. T cell receptor (TCR) repertoire profiles of CD8(+) cell subsets having strong CNAR activity exhibited increased perturbations in comparison to those of inactive subsets. Together, these studies suggest that CNAR is driven by HIV replication and that this antiviral activity is associated with oligoclonally expanded activated CD8(+) cells expressing PD-1 and having a transitional memory cell phenotype. The findings better describe the identity of CD8(+) cells showing CNAR and should facilitate the evaluation of this important immune response in studies of HIV pathogenesis, resistance to infection, and vaccine development.

T Cells Expressing the Activating NK Cell Receptors KIR2DS4, NKG2C and NKG2D Are Elevated In Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH) and Cytotoxic towards Hematopoietic Progenitor Cell Lines

AbstractAbstract 2235 Background:Paroxysmal Nocturnal Hemoglobinuria (PNH) is a disease characterized by hemolysis due to an acquired mutation in the X-linked PIG-A gene in the hematopoietic stem cell (HSC). This leads to a clone of hematopoietic cells with deficient expression of glycosyl phosphatidyl inositol (GPI) anchored proteins at the cell membrane. The clinical evolution of PNH arises through clonal expansion of PIG-A mutated HSC which is insufficiently explained by the PIG-A mutation alone. Hypothetically, clonal expansion could result from autoreactive T cells selectively attacking normal HSC, whereas GPI deficient HSC are unharmed. Methods and Results:we investigated the presence of potentially autoreactive T cells in peripheral blood of patients with PNH (n = 39) by flow cytometry. We compared T cell subset frequencies and absolute numbers with healthy controls (n = 25) using Mann-Whitney U test. In PNH patients, T cells expressing the NK cell marker CD56 were significantly elevated, both in percentage (p < 0.001) and in absolute numbers (p < 0.01). Furthermore, the frequency of T cells expressing the activating NK cell receptors (NKRs) NKG2D (p < 0.01), NKG2C (p < 0.01), and KIR2DS4 (p = 0.01) was significantly increased. KIR2DS4+, NKG2C+ and NKG2D+ T cells mainly consist of highly differentiated effector memory CD45RA+ T cells (TEMRA) (KIR2DS4: median 90%, range 70–96%, NKG2C: median 83%, range 49–99%, NKG2D: median 40%, range 38–66%). A highly variable proportion of these T cell populations consists of γδ T cells (KIR2DS4: median 28%, range 6–72%, NKG2C: median 36%, range 3–75%, NKG2D: median 11%, range 7–40%). By 10 color flow cytometry, we examined NKR coexpression patterns. KIR2DS4+ and NKG2C+ T cells mainly coexpress either only NKG2D (KIR2DS4+ T cells: median 24%, range 2 – 74%, NKG2C+ T cells: median 21%, range 3–71%), or a combination of NKG2D, NKG2C and CD158b1/b2,j, but not inhibitory NKG2A (KIR2DS4+ T cells: median 16%, range 1 – 55%, NKG2C+ T cells: median 20%, range 1–60%). In contrast, NKG2D+ T cells generally do not express any other NKRs tested (median 77%, range 53–84%). NKG2D+ KIR2DS4+ cytotoxic T lymphocyte (CTL) lines isolated from PNH patient peripheral blood and bone marrow display high cytolytic activity towards CD34+ hematopoietic progenitor cell lines and MHC class I deficient K562 cells, suggesting T cell receptor independent cytolytic activity. These NKR+ CTL lines are capable of differentially lysing GPI+ and GPI- hematopoietic cell lines, however not in all cell line models and CTL lines. This suggests that multiple factors, as for example the highly activated status of in vitro cultured CTLs, influence whether or not GPI dependent lysis occurs. Conclusion:The increased frequency of T cells expressing activating NK cell receptors KIR2DS4, NKG2C, and NKG2D, with a CD8+ effector-memory phenotype and differences in cytotoxicity towards GPI+ and GPI- hematopoietic cell lines suggests that these T cell populations may be involved in bone marrow failure and expansion of PNH clones. Disclosures:Muus: Alexion: member of advisory board.

Selective Depletion of T Cell Alloresponses Using a Photodepletion Strategy Preferentially Targets CD4+ T Cells.

AbstractAbstract 1467P-glycoprotein (Pgp) is the product of the multidrug-resistance-1 (MDR1) gene and actively transports various molecules across the extracellular membrane. Previous studies demonstrated that activated lymphocytes decrease Pgp activity and preferentially retain the photosensitizing agent 4, 5-dibromorhodamine 123 (TH9402, Kiadis Pharma, NL). We evaluated a photodepletion technique to achieve selective depletion (SD) of graft-versus-host disease (GVHD) alloreacting T cells in 24 HLA-identical sibling stem cell transplants. Donor lymphocytes were activated by 72 hr exposure with irradiated in-vitro expanded recipient T lymphocytes and pulsed with TH9402. Alloactivated T cells preferentially retaining the photosensitizer were eliminated by light exposure. The transfused cell products were then analyzed for T cell subset frequency. After SD preferential CD4+ T cell depletion occurred with an inversion of the CD4+/CD8+ ratio. Within the CD4+ compartment a significant depletion of naïve (CD27+ CD45RO-), central memory (CD27+ CD45RO+), and effector (CD27-CD45RO+) populations was noted. Conversely, CD8+ naïve and effector subsets was relatively conserved with depletion occurring predominantly in the central memory population. Additionally, an 80% reduction in B cells occurred, with a 60% reduction of cytotoxic NK cells (CD56+CD16+) and a relative expansion of regulatory NK cells (CD56+CD16-). We compared outcomes of 24 SD transplants with 34 patients receiving a T-cell depleted transplant. All patients with hematological malignancies were conditioned with fludarabine, cyclophosphamide, and total body irradiation and received a CD34-selected stem cell allograft from an HLA identical sibling. SD recipients also received 5×106/kg SD donor T cells. Low-dose cyclosporine was used as the only post-transplant immunosuppression. Median follow up was 14.5 months. The probability of severe acute GvHD (grade III-IV, 13%) and relapse (25%) was low for all patients. On day 100 post-transplant SD transplant recipients had lower absolute CD4+ counts, and increased rates of CMV reactivation requiring treatment (median 2 vs 1 reactivations within 100 days, p<0.01), and more chronic GvHD (70% vs 31%, p=0.04). Previous studies have shown that Pgp efflux of rhodamine-123 in quiescent T cells varied between subsets, with a preferential retention occurring in the CD4+ and central memory compartments (Br J Haematol. 1998 Jun;101(4):722-7). Our data is in accordance with these observations. In conclusion, while SD appeared to eliminate alloactivated T cells resulting in low frequencies of severe acute GVHD, differences in Pgp activity and dye retention led to the preferential non-specific elimination of CD4+ and central memory T cells which may have contributed to greater viral reactivation and chronic GVHD. Disclosures:No relevant conflicts of interest to declare.

Blood Myeloid Dendritic Cells from HIV-1-Infected Individuals Display a Proapoptotic Profile Characterized by Decreased Bcl-2 Levels and by Caspase-3+Frequencies That Are Associated with Levels of Plasma Viremia and T Cell Activation in an Exploratory Study

Reduced frequencies of myeloid and plasmacytoid dendritic cell (DC) subsets (mDCs and pDCs, respectively) have been observed in the peripheral blood of HIV-1-infected individuals throughout the course of disease. Accumulation of DCs in lymph nodes (LNs) may partly account for the decreased numbers observed in blood, but increased DC death may also be a contributing factor. We used multiparameter flow cytometry to evaluate pro- and antiapoptotic markers in blood mDCs and pDCs from untreated HIV-1-infected donors, from a subset of infected donors before and after receiving antiretroviral therapy (ART), and from uninfected control donors. Blood mDCs, but not pDCs, from untreated HIV-1-infected donors expressed lower levels of antiapoptotic Bcl-2 than DCs from uninfected donors. A subset of HIV-1-infected donors had elevated frequencies of proapoptotic caspase-3(+) blood mDCs, and positive correlations were observed between caspase-3(+) mDC frequencies and plasma viral load and CD8(+) T-cell activation levels. Caspase-3(+) mDC frequencies, but not mDC Bcl-2 expression, were reduced with viral suppression on ART. Apoptosis markers on DCs in blood and LN samples from a cohort of untreated, HIV-1-infected donors with chronic disease were also evaluated. LN mDCs displayed higher levels of Bcl-2 and lower caspase-3(+) frequencies than did matched blood mDCs. Conversely, LN pDCs expressed lower Bcl-2 levels than their blood counterparts. In summary, blood mDCs from untreated HIV-1-infected subjects displayed a proapoptotic profile that was partially reversed with viral suppression, suggesting that DC death may be a factor contributing to blood DC depletion in the setting of chronic, untreated HIV disease.

Tolerance Induction in Response to Liver Inflammation

Background/Aims: The liver plays an important role in immunological tolerance due to its anatomical location, as it links the gastrointestinal tract and the systemic venous circulation. Therefore, immune reactions against dietary or bacterial antigens from the gut have to be avoided. However, immune responses resulting in elimination of harmful hepatotrophic pathogens have to be induced. We investigated mechanisms of tolerance induction in response to liver inflammation in a murine model of immune-mediated liver injury. Methods: Liver damage was induced by injection of the plant lectin concanavalin A (ConA). Cytokine levels were measured in plasma and liver tissue. The frequencies of intrahepatic and splenic cell subsets were measured by FACS analyses. Results: ConA hepatitis was mediated by activation of CD4+ T cells, NKT cells and Kupffer cells releasing IFN-γ and TNF-α. Tolerance developed towards ConA rechallenge within 8 days, lasted for several weeks and was characterized by significantly reduced plasma transaminase activities, decreased Th1/Th17 responses and an increased IL-10 release, the latter being produced by CD4+CD25+FoxP3+ regulatory T cells and Kupffer cells. Moreover, regulatory T cells from ConA-tolerant mice displayed a higher immunosuppressive potential in vitro and in vivo compared to those from non-tolerant animals. Interestingly, ConA hepatitis was aggravated in CCR5^–/– and CXCR3^–/– mice. Conclusion: These results suggest that ConA tolerance is mediated by induced IL10+ regulatory T cells, probably trafficking into the liver depending on the IFN-γ-inducible chemokine receptors CCR5 and CXCR3.

Allergen-specific T cell responses to immunotherapy monitored by CD154 and intracellular cytokine expression

A sensitive measurement of low numbers of intracellular cytokine-expressing antigen-specific T cells from peripheral blood mononuclear cells (PBMC) is possible using CD154 as a marker of recently activated T cells. This technique may have potential for monitoring peripheral blood T cell responses to immunotherapy. To evaluate the applicability of this method for measuring changes in cytokine production by allergen-specific T cells in a clinical trial setting. Ex vivo ragweed-specific CD154 and intracellular cytokine expression were evaluated using a subset of subjects in an environmental chamber study of allergic rhinitis immunotherapy. PBMC were collected and cryopreserved from Amb a 1-immunostimulatory oligodeoxynucleotide conjugate (AIC)-treated (n=17) and placebo-treated (n=15) ragweed-allergic subjects both after pre- and post-treatment ragweed exposures. In vitro allergen-stimulated CD3(+)CD4(+)CD154(+) T cell intracellular IL-4, IL-5, IL-13, and IFN-gamma expression were evaluated by flow cytometry. Compared with the T helper type 2 (Th2) cytokine expression measured after pre-treatment ragweed exposures, placebo-treated subjects demonstrated a significantly elevated ragweed- and Amb a 1-specific T cell IL-4 and IL-13 co-expression (P=0.005 and P=0.022, respectively) and a significantly elevated ragweed-specific IL-5 expression (P<0.001) following post-treatment ragweed exposures. In contrast, AIC-treated subjects demonstrated no increases in allergen-specific Th2 cytokine expression following post-treatment ragweed exposures. IFN-gamma expression remained low and un-changed in both groups. Subject reported total nasal symptom scores demonstrated modest but significant correlations with Amb a 1- and ragweed-stimulated intracellular Th2 cytokine responses. Combined CD154 and intracellular cytokine staining in PBMC can be used to sensitively monitor changes in antigen-specific T cell subset frequencies in clinical studies. Antigen-specific cytokine expression moderately correlated with the reported levels of allergic symptoms.

A Systemic age dependent defect in immune-cell signaling response induced by inflammation (138.2)

Abstract Immune system function generally degrades with age and is associated with increased risk of infection and disease. Though differences between young and old have been noted in many immune system components, no system wide understanding of how these disparate observation act together exists to date, nor how they relate to genes found to associated with increased longevity, many of which are immune related. Here we characterize the immune system of 29 young and old individuals by concurrently measuring from peripheral blood, immune cell subset frequency, serum cytokines, gene expression and individual cellular responses to cytokine stimuli by pathway specific phospho-protein abundance. We identify age-dependent changes in STAT signaling baseline and in response to stimulation by a panel of 7 different cytokines, particularly prominent in CD8 and CD4 T cells, but also in monocytes and B-cells. The observed differences in cellular responses are not due to adaptation to higher level of cytokine stimuli but rather to an inert inability to mount a full response, many times augmented by a higher base line phosphorylation level in the elderly. We construct an immune network spanning multiple biological layers and identify co-occurring modules which link longevity associated genes with these cellular immune phenotypes. We quantify the contributions of these modules to the observed reduction in cellular response to stimuli in the elderly and suggest a common responsible mechanism.

Characteristics of peripheral NK cells in hepatocellular carcinoma patients

Functional defects in NK cells have been proposed to be responsible for the impairment of anti-tumor immune responses. However, it remained unclear whether the function of NK cells were impaired in patients with hepatocellular carcinoma. To address this issue, we analyzed the frequency and function of peripheral NK cell subsets in hepatocellular carcinoma (HCC) patients. 35 HCC patients and 24 healthy controls (HC) were enrolled in the study. Peripheral NK frequency was analyzed using flow cytometry. In addition, the capacity of NK cells to produce IFN gamma and to lyse K562 cells was evaluated. In contrast with the healthy controls, the frequency of peripheral NK cells in hepatocellular carcinoma patients was decreased (12.19%+/-10.85% vs 24.01%+/-8.78%, u = 4.01, probability value less than 0.01), while the frequency of CD56(bright)CD16(neg) NK cells was increased (0.62%+/-0.39% vs 0.48%+/-0.28%, u = 1.96, probability value less than 0.05), and the frequency of CD56(dim)CD16(pos) NK cells was significantly decreased (11.59%+/-7.49% vs 22.66%+/-8.84%, u = 3.92, probability value less than 0.01). In addition, peripheral NK cells from HCC patients exhibited decreased capacity to produce IFN gamma (effective cells 13.31%) and to lyse K562 cells (mixed ratio 30:1, 10:1, 1:1, effective cells 16.72%+/-7.33% vs 26.29%+/-12.36%, u = 2.52, P less than 0.05, 8.01%+/-4.40% vs 13.09%+/-5.03%, u = 3.32, probability value less than 0.05, 3.51%+/-2.82% vs 3.42%+/-1.64%, u = 1.56, probability value more than 0.05, respectively) as compared with healthy subjects. Anti-tumor activity of NK cells in HCC patients was impaired.

Chronic HIV-1 viremia reverses NKG2A/NKG2C ratio on natural killer cells in patients with human cytomegalovirus co-infection

The HIV-1-induced expansion of highly dysfunctional natural killer (NK) cell subsets represents a strategy to evade NK cell antiviral functions. In this context, the loss of NKG2A NK cells in chronic viremic HIV-1-infected individuals has also been associated with a dramatic expansion of NKG2C NK cells. The viral trigger associated with high frequencies of NK cell subsets expressing NKG2C is still being debated. To confirm that human cytomegalovirus (HCMV) infection is necessary for the expansion of NKG2C NK cells and to assess whether this phenomenon affects NKG2A/NKG2C ratio on NK cells in patients coinfected with HIV-1 and HCMV. We measured the expression of NKG2A and NKG2C on NK cells from 70 healthy donors, 21 early, 96 chronic and 27 long-term nonprogressor's (LTNPs) HIV-1-infected patients using a multicolor flow cytometric approach. HCMV infection was detected by titrating the serum levels of specific circulating antibodies. A significant expansion of NKG2C NK cells could be detected only in HCMV-infected patients. This phenotypic feature, together with the HIV-1-mediated downmodulation of NKG2A, pathologically reverses the ratio of NKG2A/NKG2C uniquely on NK cells from chronic viremic HIV-1-infected patients with a concomitant HCMV infection. The normalization of NKG2A/NKG2C ratio to values more than one occurred only after 24 months of suppression of HIV-1 replication following antiretroviral therapy. The inversion of NKG2A/NKG2C ratio characterizes advanced stages of HIV-1 disease in patients showing a concomitant HCMV infection. This NK cell immune parameter renders this cohort of patients distinguishable from LTNPs and early HIV-1-infected individuals.

Insights on Chronic-Relapsing Opsoclonus-Myoclonus From a Pilot Study of Mycophenolate Mofetil

Opsoclonus-myoclonus syndrome is characterized by abnormal lymphocyte trafficking into brain. The authors hypothesized that mycophenolate mofetil, a lymphocyte proliferation inhibitor, might be therapeutic. The cerebrospinal fluid and blood immunophenotypes of 15 children with predominantly chronic-relapsing opsoclonus-myoclonus syndrome were compared before and after treatment by flow cytometry. Mycophenolate mofetil reduced the cerebrospinal fluid expansion of HLA-DR+ activated T cells (-40%); the frequency of other T-cell or natural killer cell subsets remained unchanged, but cerebrospinal fluid B cells increased significantly. Adrenocorticotropic hormone dose was lowered by 64% over an average of 1.5 years, yet 73% eventually relapsed despite therapeutic drug levels. Prior treatment with rituximab prevented relapse-associated increase in cerebrospinal fluid B cells, without hindering mycophenolate mofetil-induced reduction in T-cell activation. These data demonstrate resistant immunologic problems in chronic-relapsing opsoclonus-myoclonus syndrome. Mycophenolate mofetil did not prevent relapse. The novel effect of mycophenolate mofetil on chronically activated T cells may contribute to its efficacy in T-cell mediated neurological disorders.

Significantly skewed memory CD8 + T cell subsets in HIV-1 infected infants during the first year of life

HIV-1 infection causes a severe T cell compromise; however, little is known about changes in naive, memory, effector and senescent T cell subsets during the first year of life. T cell subsets were studied over the first year of life in blood from 3 infant cohorts: untreated HIV-infected, HIV-exposed but uninfected, and HIV-unexposed. In HIV-infected infants, the frequency of CCR7 +CD45RA + naive CD8 + T cells was significantly decreased, while the frequency of CCR7 −CD45RA − effector memory CD8 + T cells was increased, compared with the control cohorts. A larger population of CD8 + T cells in HIV-infected infants displayed a phenotype consistent with senescence. Differences in CD4 + T cell subset frequencies were less pronounced, and no significant differences were observed between exposed and unexposed HIV-uninfected infants. We concluded that the proportion of naive, memory, effector and senescent CD8 + T cells during the first year of life is significantly altered by HIV-1 infection.

Nine‐color flow cytometry for accurate measurement of T cell subsets and cytokine responses. Part II: Panel performance across different instrument platforms

Cellular immune responses elicited by vaccination are complex and require polychromatic analysis to accurately characterize the phenotype and function of rare, responding cells. Technical challenges and a lack of instrument standardization between research sites have limited the application of polychromatic cytometry in multicenter clinical trials. Two previously developed six-color T cell subset immunophenotyping reagent panels deliberately designed to accommodate three additional low frequency functional measurements were compared for their reproducibility of staining across three different flow cytometers. We repeatedly measured similar T cell subset frequencies between the two reagent panels and across the three different cytometers. Spectral overlap reduced sensitivity in two of the three open measurement channels (PE [IL-2] and APC [IFN gamma]) for one reagent combination, particularly in subsets with low cytokine expression. There was no significant interassay variation for measurements across instrument platforms. Careful panel design will identify reagent combinations that minimize spectral spillover into channels reserved for cytokine measurement and comparable results can be achieved using different cytometers, however, it is important to establish standardized quality control procedures for each instrument to minimize variation between cytometers.

Inappropriate notch activity and limited mesenchymal stem cell plasticity in the bone marrow of patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are a heterogeneous group of hematological disorders characterized by ineffective hematopoiesis, enhanced bone marrow apoptosis and frequent progression to acute myeloid leukemia. Several recent studies suggested that, besides the abnormal development of stem cells, microenvironmental alterations are also present in the MDS bone marrow. In this study, we have examined the relative frequencies of stem and progenitor cell subsets of MDS and normal hematopoietic cells growing on stromal cell layers established from MDS patients and from normal donors. When hematopoietic cells from MDS patients were co-cultured with normal stromal cells, the frequency of either early or late cobblestone area-forming cells (CAFC) was significantly lower compared to the corresponding normal control values in 4 out of 8 patients. In the opposite situation, when normal hematopoietic cells were incubated on MDS stromal cells, the CAFC frequencies were decreased in 5 out of 6 patients, compared to normal stromal layer-containing control cultures. Moreover, a soluble Notch ligand (Jagged-1 protein) was an inhibitor of day-35-42 CAFC when normal hematopoietic cells were cultured with normal or MDS stromal cells, but was unable to inhibit MDS stem and early progenitor cell growth (day-35-42 CAFC) on pre-established stromal layers. These findings suggest that in early hematopoietic cells isolated from MDS patients the Notch signal transduction pathway is disrupted. Furthermore, there was a marked reduction in the plasticity of mesenchymal stem cells of MDS patients compared with those of normal marrow donors, in neurogenic and adipogenic differentiation ability and hematopoiesis supporting capacity in vitro. These results are consistent with the hypothesis that when alterations are present in the myelodysplastic stroma environment along with intrinsic changes in a hematopoietic stem/progenitor cell clone, both factors might equally contribute to the abnormal hematopoiesis in MDS.

KIR Gene and KIR Ligand Analysis to Predict Graft Rejection After Renal Transplantation

The identification of transplant patients at high risk for rejection after reduction of immunosuppression would allow minimization of immunosuppression and avoidance of side effects in low-risk patients. Next to T cells, innate natural killer (NK) cells may contribute to graft rejection. NK cell activation depends on the balance between activating and inhibitory signals, delivered by self-human leukocyte antigens (HLA) through binding of killer-cell immunoglobulin receptors (KIR). In transplantation, KIR and/or HLA mismatching may lead to NK cell activation. In this study, we have evaluated whether acute rejection after reduction of immunosuppression after renal transplantation was associated with peripheral blood NK cell frequencies or with predicted NK cell alloreactivity based on KIR gene and ligand analysis. HLA and KIR genotyping was used to analyze the presence of single KIR genes and haplotypes, and to predict NK cell alloreactivity based on the "missing self" and "missing ligand" hypothesis. NK cell frequencies were analyzed using flow cytometry. No association was found between NK cell alloreactivity based on KIR gene analysis or peripheral blood NK cell subset frequencies and the occurrence of acute rejection after reduction of immunosuppression. Our data suggest that in a setting where immunosuppression is reduced, prior analysis of NK cell reactivity cannot identify patients at risk for subsequent graft rejection.