Hematopoietic Chimerism Following Non-Myeoloablative Stem Cell Transplantation Is Dependent on NK Cell Tolerance.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 45-45
Author(s):  
Geert Westerhuis ◽  
Wendy G. Maas ◽  
Roelof Willemze ◽  
Rene E. Toes ◽  
Willem E. Fibbe
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Cell Depletion ◽  
Cell Tolerance ◽  
Spleen Cells ◽  
Elimination Kinetics ◽  
Donor Cells

Abstract NK cells are able to eliminate major mismatched hematopoietic cells and, in addition to T cells, represent a second barrier that prevents engraftment following transplantation over MHC barriers. Here, we studied the role of NK cells in the elimination of major mismatched hematopoietic cells in a Balb/c into B6 transplantation model after anti-CD40L (MR1) treatment. In this model, survival of donor cells was determined using an in-vivo cytotoxicity assay based on the infusion of differentially CFSE-labeled syngeneic and donor splenocytes. Likewise, the efficacy of treatment was determined directly by assessing the level of chimerism three months after transplantation. Four weeks after the infusion of 106 bone marrow cells (BMC), B6 mice rejected donor spleen cells within 3 hours. A combination with anti-CD40L treatment prevented this early elimination and these mice showed the same elimination kinetics as observed in untreated mice (97.0 ± 1.3% vs. 96.6 ± 1.3% in 3 days). These results indicate that anti-CD40L treatment prevents the induction of a memory T cell response after infusion of donor BMC. Nonetheless, elimination of donor cells was still present within 3 days, therefore we hypothesized that the elimination of donor cells was mediated by NK cells, rather than by T cells. A detailed analysis of the elimination kinetics in untreated B6 mice showed that the CFSE-labeled Balb/c splenocytes were gradually eliminated starting from the moment of infusion. Similar elimination kinetics were observed in T cell-deficient B6 nu/nu mice. In addition, in-vivo treatment with a depleting anti-NK cell antibody (PK136) prolonged the survival of donor splenocytes in both B6 and B6 nu/nu mice (54.7 ± 2.8% vs. 8.4 ± 5.9% in 2 days in B6 mice and 72.4 ± 7.2% vs. 19.4 ± 8.6% in 1 day in B6 nu/nu mice). A similarly prolonged survival of donor spleen cells was observed in NK cell-depleted mice that had received 106 BMC 4 weeks earlier in combination with anti-CD40L (77.4 ± 15.6% with NK cell depletion vs. 5.3 ± 0.6% without NK cell depletion in 2 days), while no effect was observed after in-vivo treatment with a depleting anti-CD8 antibody. Infusion of increasing numbers of Balb/c BMC (106, 107, 108) after treatment with anti-CD40L resulted in a dose-dependent prolongation of the survival of donor splenocytes, but up to 108 BMC were needed for complete non-responsiveness. This indicated that transplantation of 108 BMC resulted in tolerization of NK cells, which was also associated with stable chimerism (36.1 ± 14.0% of the GR-1+ fraction). In-vivo depletion of NK cells before transplantation allowed stable chimerism in mice treated with anti-CD40L and only 30 x 106 BMC (5/5 vs. 1/5 without NK cell depletion). These data demonstrate that: 1) The elimination of Balb/c donor splenocytes in untreated B6 recipient mice is mediated by NK cells. 2) In mice treated with donor BMC and anti-CD40L the elimination of donor splenocytes can be delayed by NK cell depletion or by increasing the initial dose of donor BMC. 3) NK cell tolerance over MHC barriers can be induced by transplantation of a high number of BMC (108) and results in sustained engraftment and chimerism. 4) Additional NK cell depletion allows sustained chimerism following transplantation of a lower number (30 x 106) of BMC. We conclude that the induction of NK cell tolerance is dependent on the dose of donor BMC injected. This may explain the high numbers of BMC required for engraftment over MHC barriers.

Long-term mixed chimerism after immunologic conditioning and MHC-mismatched stem-cell transplantation is dependent on NK-cell tolerance

Blood ◽  
2005 ◽  
Vol 106 (6) ◽  
pp. 2215-2220 ◽  
Author(s):  
Geert Westerhuis ◽  
Wendy G. E. Maas ◽  
Roel Willemze ◽  
René E. M. Toes ◽  
Willem E. Fibbe
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Nk Cells ◽  
Bone Marrow Cells ◽  
Nk Cell ◽  
Mixed Chimerism ◽  
Cell Tolerance ◽  
Donor Cells ◽  
Marrow Cells

Abstract T-cell tolerance is mandatory for major histocompatibility complex (MHC)-mismatched stem-cell transplantation without cytoreduction. Here, we used a cytotoxicity assay based on the infusion of differentially carboxyfluorescein succinimidyl ester (CFSE)-labeled syngeneic and donor splenocytes to determine the survival of donor cells in vivo. In vivo cytotoxicity data showed that treatment with anti-CD40 ligand monoclonal antibody in combination with a low dose of MHC-mismatched bone marrow cells was sufficient to induce T-cell tolerance. However, CFSE-labeled donor cells were still eliminated. A similar elimination pattern was observed in T-cell and natural killer T-cell (NKT-cell)-deficient mice, suggesting the involvement of natural killer (NK) cells. Indeed, in vivo NK-cell depletion resulted in a prolonged survival of CFSE-labeled donor cells, confirming the role of NK cells in this process. Transplantation of a megadose of MHC-mismatched bone marrow cells was required for a complete survival of CFSE-labeled donor cells. This NK-cell tolerance was donor specific and was associated with mixed chimerism. Additional NK-cell depletion significantly enhanced engraftment and allowed long-term chimerism after transplantation of a relatively low dose of donor bone marrow cells. These data demonstrate the importance of NK cells in the rejection of MHC-mismatched hematopoietic cells and may explain the high numbers of bone marrow cells required for transplantation over MHC barriers. (Blood. 2005;106:2215-2220)

scholarly journals Anti-tumor effects of RTX-240: an engineered red blood cell expressing 4-1BB ligand and interleukin-15

2021 ◽  
Author(s):  
Shannon L. McArdel ◽  
Anne-Sophie Dugast ◽  
Maegan E. Hoover ◽  
Arjun Bollampalli ◽  
Enping Hong ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Blood Cell ◽  
Nk Cells ◽  
Red Blood Cell ◽  
Safety Profile ◽  
Nk Cell ◽  
Cell Activity ◽  
In Vivo Studies

AbstractRecombinant agonists that activate co-stimulatory and cytokine receptors have shown limited clinical anticancer utility, potentially due to narrow therapeutic windows, the need for coordinated activation of co-stimulatory and cytokine pathways and the failure of agonistic antibodies to recapitulate signaling by endogenous ligands. RTX-240 is a genetically engineered red blood cell expressing 4-1BBL and IL-15/IL-15Rα fusion (IL-15TP). RTX-240 is designed to potently and simultaneously stimulate the 4-1BB and IL-15 pathways, thereby activating and expanding T cells and NK cells, while potentially offering an improved safety profile through restricted biodistribution. We assessed the ability of RTX-240 to expand and activate T cells and NK cells and evaluated the in vivo efficacy, pharmacodynamics and tolerability using murine models. Treatment of PBMCs with RTX-240 induced T cell and NK cell activation and proliferation. In vivo studies using mRBC-240, a mouse surrogate for RTX-240, revealed biodistribution predominantly to the red pulp of the spleen, leading to CD8 + T cell and NK cell expansion. mRBC-240 was efficacious in a B16-F10 melanoma model and led to increased NK cell infiltration into the lungs. mRBC-240 significantly inhibited CT26 tumor growth, in association with an increase in tumor-infiltrating proliferating and cytotoxic CD8 + T cells. mRBC-240 was tolerated and showed no evidence of hepatic injury at the highest feasible dose, compared with a 4-1BB agonistic antibody. RTX-240 promotes T cell and NK cell activity in preclinical models and shows efficacy and an improved safety profile. Based on these data, RTX-240 is now being evaluated in a clinical trial.

scholarly journals DNAM-1 promotes activation of cytotoxic lymphocytes by nonprofessional antigen-presenting cells and tumors

2008 ◽  
Vol 205 (13) ◽  
pp. 2965-2973 ◽  
Author(s):  
Susan Gilfillan ◽  
Christopher J. Chan ◽  
Marina Cella ◽  
Nicole M. Haynes ◽  
Aaron S. Rapaport ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Adhesion Molecules ◽  
Cd8 T Cells ◽  
Nk Cell ◽  
Cd8 T Cell ◽  
Antigen Presenting

Natural killer (NK) cells and CD8 T cells require adhesion molecules for migration, activation, expansion, differentiation, and effector functions. DNAX accessory molecule 1 (DNAM-1), an adhesion molecule belonging to the immunoglobulin superfamily, promotes many of these functions in vitro. However, because NK cells and CD8 T cells express multiple adhesion molecules, it is unclear whether DNAM-1 has a unique function or is effectively redundant in vivo. To address this question, we generated mice lacking DNAM-1 and evaluated DNAM-1–deficient CD8 T cell and NK cell function in vitro and in vivo. Our results demonstrate that CD8 T cells require DNAM-1 for co-stimulation when recognizing antigen presented by nonprofessional antigen-presenting cells; in contrast, DNAM-1 is dispensable when dendritic cells present the antigen. Similarly, NK cells require DNAM-1 for the elimination of tumor cells that are comparatively resistant to NK cell–mediated cytotoxicity caused by the paucity of other NK cell–activating ligands. We conclude that DNAM-1 serves to extend the range of target cells that can activate CD8 T cell and NK cells and, hence, may be essential for immunosurveillance against tumors and/or viruses that evade recognition by other activating or accessory molecules.

scholarly journals Novel APC-like properties of human NK cells directly regulate T cell activation

2015 ◽  
Author(s):  
Jacob Hanna ◽  
Ofer Mandelboim
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Mhc Class Ii ◽  
T Cell Activation ◽  
Cell Activation ◽  
Nk Cell ◽  
Adaptive Immune Response ◽  
Antigen Uptake

Initiation of the adaptive immune response is dependent on the priming of naive T cells by APCs. Proteomic analysis of unactivated and activated human NK cell membrane-enriched fractions demonstrated that activated NK cells can efficiently stimulate T cells, since they upregulate MHC class II molecules and multiple ligands for TCR costimulatory molecules. Furthermore, by manipulating antigen administration, we show that NK cells possess multiple independent unique pathways for antigen uptake. These results highlight NK cell-mediated cytotoxicity and specific ligand recognition by cell surface-activating receptors on NK cells as unique mechanisms for antigen capturing and presentation. In addition, we analyzed the T cell-activating potential of human NK cells derived from different clinical conditions, such as inflamed tonsils and noninfected and CMV-infected uterine decidual samples, and from transporter-associated processing antigen 2–deficient patients. This in vivo analysis revealed that proinflammatory, but not immune-suppressive, microenvironmental requirements can selectively dictate upregulation of T cell-activating molecules on NK cells. Taken together, these observations offer new and unexpected insights into the direct interactions between NK and T cells and suggest novel APC-like activating functions for human NK cells.

Cytotoxic cells induced during lymphocytic choriomeningitis virus infection of mice: natural killer cell activity in cultured spleen leukocytes concomitant with T-cell-dependent immune interferon production

1980 ◽  
Vol 30 (2) ◽  
pp. 473-483
Author(s):  
R M Welsh ◽  
W F Doe
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Cytotoxic T Cells ◽  
Cell Activity ◽  
Lymphocytic Choriomeningitis ◽  
Type I ◽  
Spleen Cells

The characteristics and specificities of spleen and peritoneal cytotoxic cells generated during lymphocytic choriomeningitis virus (LCMV) infection of C3H/St mice were examined. Activated natural killer (NK) cell activity was identified in fresh leukocyte populations from the 2nd to 8th days postinfection, whereas virus-specific cytotoxic T-cell activity was detected from the 6th to 14th days. When leukocytes were cultured overnight at 37 degrees C before assay, T-cell activity was still observed, but nonspecific activated NK cell-like cytotoxicity was only detected on the 6th and to a lesser degree the 8th day postinfection. Overnight culture of leukocytes taken earlier in the infection eliminated their NK cell activity. Similar activities were seen with spleen cell, plastic-adherent peritoneal cell, and nonadherent peritoneal cell populations. The virus-specific cytotoxicity observed with adherent peritoneal cells was due to contamination with cytotoxic T cells, as shown by H-2-restricted cytotoxicity and sensitivity to anti-theta antibody and complement. The nonspecific cultured day 6 effector cell from either the spleen or peritoneum displayed killing specificities and other physical properties identical to those of activated NK cells, but had sensitivities to anti-theta antibody and complement intermediate between activated day 3 NK cells and cytotoxic T cells. Culture stable NK-like cells were not found in athymic nude mice, suggesting a T-cell-dependent mechanism. Whereas LCMV spleen homogenates contained 10-fold-higher levels of interferon at day 2 than at day 6 postinfection, substantially more (nearly 20-fold) interferon was made in cultures of day 6 cells than day 2 cells. Spleen interferon was predominantly type I, whereas the culture interferon was predominantly type II, as shown by acid lability studies. Significant levels of interferon were produced by nylon-wool-passed day 6 spleen cells, and virtually all interferon production was eliminated by treatment of either day 2 or day 6 cells with antibody to theta antigen and complement, suggesting that T cells produced the interferon in vitro. Furthermore, athymic nude mice had no culture-stable NK cells 6 days postinfection, and spleen cells from them failed to produce significant levels of interferon in vitro. Addition of interferon (type I, fibroblast) to cultured C3H spleen cells affect the already elevated levels of cytotoxicity in day 6 cultures, suggesting that the NK cells in the day 6 culture were already activated. Our results suggest that T cells responding to LCMV infection secrete interferon type II which causes the continued activation of NK cells in culture. The resulting population of activated NK cells therefore appears to be relatively stable in culture and to express more theta antigen because of this T-cell dependence. Although one could mistakenly or allospecific cytotoxic T cells or cytotoxic macrophages, more careful examination shows that they are most likely activated NK cells...

NK Cells Induce Alloreactive Donor T Cell Apoptosis and Decrease Proliferation in GVHD Induction.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2162-2162
Author(s):  
Janelle A. Olson ◽  
Dennis B. Leveson-Gower ◽  
Andreas Beilhack ◽  
Robert S. Negrin
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Lymph Nodes ◽  
Nk Cells ◽  
Nk Cell ◽  
Cell Trafficking ◽  
Peripheral Lymph ◽  
Donor T Cells

Abstract Natural Killer (NK) cells have the ability to suppress graft-versus-host disease (GVHD) while inducing a graft-versus-tumor response (GVT) during allogeneic bone marrow transplantation (BMT). Previous studies in allogeneic BMT models have shown NK cell trafficking to and proliferation in lymphoid organs and GVHD target organs, which are also sites of donor T cell trafficking. This study aims to investigate the impact of NK cells on alloreactive, GVHD-inducing donor T cells. Interleukin-2 activated allogeneic NK cells isolated from C57Bl6 (H–2b) or FVB (H–2q) animals were transplanted along with T cell-depleted bone marrow into lethally irradiated BALB/c (H–2d) mice, followed 2 days later by luciferase-expressing CD4+ and CD8+ conventional T cells from the same donor strain (NK+Tcon group). Control mice received lethal irradiation and T cell-depleted bone marrow on day 0, and luciferase-expressing T cells on day 2 after transplant (Tcon group). Bioluminescence imaging of NK+Tcon mice revealed a significantly lower T cell bioluminescent signal (p=0.03 for FVB into BALB/c on day 6) than from Tcon mice. CFSE proliferation analysis of alloreactive T cells on day 3 after transplant showed no significant change in the percent of donor T cells that have divided in the spleen, and only a slight decrease in the percent of T cells that have divided in the lymph nodes when NK cells are present. However, at this timepoint 82% of the proliferating cells have divided past the third generation, in contrast to 64% in the NK+Tcon mice. Donor T cells in both groups become equally activated in vivo, expressing similar levels of the early-activation marker CD69. T cells re-isolated from NK+Tcon animals at day 5 stained 2 to 10-fold higher for the TUNEL apoptosis marker than those from Tcon mice in the mesenteric and peripheral lymph nodes, respectively (p<0.0001). Additionally, decreased numbers of T cells were re-isolated from the peripheral lymph nodes in the NK+Tcon group as compared to the Tcon group. This increase in TUNEL staining was not seen when the transplanted NK cells were isolated from a perforin-deficient donor. This indicates that NK cells in lymph nodes use a perforin-dependent mechanism to increase apoptosis in proliferating, alloreactive donor T-cells, which are syngeneic to the transplanted NK cells. Donor T cells re-isolated from the lymph nodes of transplanted mice up-regulate the NKG2D ligand Rae1γ as compared to naïve T cells, as shown by FACS. This suggests that NK cells may cause direct lysis of alloreactive donor T cells in vivo during GVHD induction, mediated by the NK cell activating receptor NKG2D. This study provides crucial mechanistic information regarding the function of NK cells in suppressing GVHD.

Targeting CD137 to enhance the antitumor efficacy of cetuximab by stimulation of innate and adaptive immunity.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3015-3015 ◽  
Author(s):  
Holbrook Edwin Kohrt ◽  
Roch Houot ◽  
Kipp Weiskopf ◽  
Matthew Goldstein ◽  
Peder Lund ◽  
...  
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Adaptive Immunity ◽  
Cd8 T Cells ◽  
Nk Cell ◽  
Cell Depletion ◽  
Innate And Adaptive Immunity ◽  
Cetuximab Therapy

3015 Background: Cetuximab therapy results in beneficial, yet limited, clinical improvement for patients with KRAS wildtype (WT) colorectal (CRC) and head and neck (HN) cancer. The efficacy of cetuximab, an IgG1 monoclonal antibody against EGFR, is due in part to antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells. CD137 is a costimulatory molecule expressed following activation on NK and memory, antigen-specific, CD8 T cells. Methods: We investigated the hypothesis that the combination of cetuximab with anti-CD137 mAb will enhance innate and adaptive immunity, thereby improving cetuximab’s anti-tumor efficacy in preclinical models and a prospective trial, NCT01114256. Results: NK cells increased their expression of CD137 by a factor of 30-40 when exposed to cetuximab-coated, EGFR-expressing HN and CRC cell lines. An agonistic anti-CD137 mAb enhanced NK cell degranulation and cytotoxicity 2-fold (~45 to 90% tumor lysis assayed by chromium release). The combination of cetuximab and anti-CD137 mAbs was synergistic in a syngeneic, human-EGFR-transfected murine tumor leading to complete tumor resolution and prolonged survival. NK cell depletion, significantly, and CD8 T cell depletion, partly, abrogated the anti-tumor efficacy of this combination. A series of HN and both KRAS WT and mutant CRC xenotransplant models demonstrated synergy with cetuximab and anti-CD137 mAbs. In our clinical trial, 54 patients with HN cancer receiving cetuximab therapy, circulating and intratumoral NK cells upregulated CD137 with amplitude influenced by duration post-cetuximab and host FcyRIIIa polymorphism. Interestingly, in 10 HLA-A2+ patients, following cetuximab, an increase in EGFR-specific, CD137-expressing, CD8 T cells directly correlated with the percent increase in CD137-expressing NK cells. Conclusions: Our results demonstrate the synergy of combining an agonistic mAb, anti-CD137, augmenting ADCC and T cell memory following a tumor-targeting mAb, cetuximab, in HN and KRAS mutant and WT CRC cancer. These results support a novel, sequential antibody approach by targeting first the tumor and then the host innate and adaptive immune system. Clinical trial information: NCT01114256.

scholarly journals Adenovirus Vector Vaccination Impacts NK Cell Rheostat Function following Lymphocytic Choriomeningitis Virus Infection

2018 ◽  
Vol 92 (11) ◽  
Author(s):  
Eryn Blass ◽  
Malika Aid ◽  
Amanda J. Martinot ◽  
Rafael A. Larocca ◽  
Zi Han Kang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Adenovirus Vector ◽  
T Cell Responses ◽  
Lymphocytic Choriomeningitis ◽  
Cell Depletion ◽  
Cell Responses ◽  
Lcmv Infection

ABSTRACT Natural killer (NK) cells respond rapidly as a first line of defense against infectious pathogens. In addition, NK cells may provide a “rheostat” function and have been shown to reduce the magnitude of antigen-specific T cell responses following infection to avoid immunopathology. However, it remains unknown whether NK cells similarly modulate vaccine-elicited T cell responses following virus challenge. We used the lymphocytic choriomeningitis virus (LCMV) clone 13 infection model to address whether NK cells regulate T cell responses in adenovirus vector-vaccinated mice following challenge. As expected, NK cell depletion in unvaccinated mice resulted in increased virus-specific CD4 + and CD8 + T cell responses and immunopathology following LCMV challenge. In contrast, NK cell depletion had minimal to no impact on antigen-specific T cell responses in mice that were vaccinated with an adenovirus serotype 5 (Ad5)-GP vector prior to LCMV challenge. Moreover, NK cell depletion in vaccinated mice prior to challenge did not result in immunopathology and did not compromise protective efficacy. These data suggest that adenovirus vaccine-elicited T cells may be less sensitive to NK cell rheostat regulation than T cells primed by LCMV infection. IMPORTANCE Recent data have shown that NK cell depletion leads to enhanced virus-elicited T cell responses that can result in severe immunopathology following LCMV infection in mice. In this study, we observed that NK cells exerted minimal to no impact on vaccine-elicited T cells following LCMV challenge, suggesting that adenovirus vaccine-elicited T cells may be less subject to NK cell regulation. These data contribute to our understanding of NK cell regulatory functions and T cell-based vaccines.

Analysis of Factors Influencing Natural Killer (NK) Cell Activity during the Early Phase after Allogeneic Stem Cell Transplantation (SCT).

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2192-2192
Author(s):  
Lars Fischer ◽  
Olaf Penack ◽  
Chiara Gentilini ◽  
Eckhard Thiel ◽  
Uharek Lutz
Keyword(s):  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Absolute Number ◽  
Cell Depletion ◽  
Reduced Intensity Conditioning ◽  
T Cell Depletion ◽  
The Mean ◽  
The Absolute

Abstract Background: After allogeneic SCT, NK cell mediated cytotoxicity is an important defense mechanism against residual tumor cells and viral infections. Using a novel flow cytometric assay, which detects the lytic granule membrane protein CD107a as a marker for NK cell degranulation, we investigated the effect of in vivo T cell depletion and the type of conditioning on NK cell function in the early phase after transplantation. Methods: At day +30 and day +90 after allogeneic SCT with regular (n=14) and dose reduced conditioning (n=8), PBMCs were coincubated at 37°C for 3 h with the NK sensitive cell line HL60. 20μl of PE-Cy5 conjugated anti-CD107a monoclonal antibody (moAb) was added to each tube containing 400μl effector/target cell suspension (2x106 cells, E:T ratio 1:1) prior to incubation. After 1 hour, 10μl of monensin (2mM) was added. After incubation for 3 hours, the cells were stained with conjugated moAb (CD56, CD16, CD3) for flow cytometry. The percentage of CD107a expressing NK cells was assessed and the absolute number of degranulating NK cells /μl was calculated. Results were compared to values from 15 healthy controls. Results: Twenty two patients (pts.) were investigated. Fourteen pts. received a conventional conditioning regimen and eight a reduced intensity conditioning. T cell depletion was applied in 15/22 pts. (ATG n=12, alemtuzumab n=2, 1 OKT-3 n=1). The type of donor included MRD (n=7) and MUD (n=15). At day +30, the proportion of NK cells with cytotoxic activity (indicated by the mean percentage of degranulating CD107a+/CD56+ cells) was significantly reduced as compared to normal donors (2.6% vs. 5.6%, p<0.001). At day +90 the percentage of degranulating NK cells was still decreased compared to normal (3.5%, p=0.007). The predominant proportion of degranulating cells was in the CD56dim/CD16− subpopulation (mean 9.8%). After conventional conditioning, the mean percentage of CD107a+ cells was 1,9% at day +30, compared to 4,0% in patients with reduced intensity conditioning (p=0.21). The absolute number of degranulating NK cells was significantly reduced after conventional conditioning (4.1/μl vs. 19.8/μl, p=0.011). Interestingly, we found no influence of in vivo T cell depletion with ATG on the mean value for CD107a+ cells at day +30 (2.5% vs. 2.9%, p=0.77). Conclusion: Although the proportion of NK cells is increased after allogeneic SCT, our data suggest that the cytotoxic activity of these cells is considerably reduced. The absolute number of NK cells with cytotoxic activity is significantly higher after reduced intensity conditioning which may contribute to the effectiveness of these regimens. Antibody induced in vivo T cell depletion with ATG showed no impact on NK cell activity during the first two months post SCT.

Mature T Cells in the Graft Improve NK Cells Reconstitution after Haploidentical Hematopoietic Stem Cell Transplantation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3120-3120
Author(s):  
Stephanie Nguyen ◽  
Mathieu Kuentz ◽  
Jean-Paul Vernant ◽  
Nathalie Dhedin ◽  
Oualid Bouteraa ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Cell Depletion ◽  
Specific Lysis ◽  
T Cell Depletion ◽  
Donor T Cells ◽  
Nk Cell Differentiation

Abstract We previously demonstrated that natural killer (NK) cells generated after haploidentical stem-cell transplantation (SCT) are blocked at an immature state characterized by phenotypic features and impaired functioning, a blockage that may affect transplantation outcome (Nguyen et al. Blood 2005). Hypothesizing that the absence of mature donor T cells in the graft may affect NK cell differentiation and function, we examined NK cells from 21 patients who received haploidentical SCT from relatives for advanced malignant hematopoietic disease and underwent either partial (pTCD) (CD3+ in the graft >1x105/Kg, mean: 6.9x105/Kg; n=11) or extensive (e-TCD) (CD3+ in the graft<1x105/Kg; mean: 0.35x105/Kg; n=10) T cell depletion and compared them with NK cells from their healthy donors. As previously described, compared with donor cells, recipient NK cells expressed lower levels of inhibitory KIR (in particular KIR2DL1 and KIR2DL2) and higher levels of CD94/NKG2A receptors after transplant (mean expression of CD94/NKG2A on recipient NK cell at 3 months post-transplant: 93.4%±7.2% versus 49.6%±10.9% on donor NK cells, p<0.0001), but these levels did not differ significantly between the pTCD and eTCD groups. However, the frequency of the immunoregulatory CD3−CD56bright NK subset was sharply lower in the pTCD than eTCD groups after transplantation (25.0%±9.6% versus 53.3%±18.0 at 3 months; p<0.001). The level of NKp30 receptors on NK cells was also higher after pTCD than eTCD transplantation (70.3%±7.1% versus 58.0%±6.5%, p=0.013) and that of pTCD patients resembled the donor NK repertoire. NK cytotoxicity against primary haplomismatched AML blasts was significantly more pronounced after pTCD than eTCD transplants (29.0%±8.9% specific lysis versus 6.7%±4.1% at a ratio Effector/Target (E/T):20/1, p=0.002), although still lower than in donor NK cells (mean specific lysis of donor NK cells from both groups against AML blasts: 43.5%±13% at a ratio E/T: 20/1). This more mature phenotypic and functional profile of NK cells after pTCD transplant was clinically associated with a lower rate of relapse and superior survival (1/11 relapse, 3/11 patients alive in complete remission at 11, 10 and 3 years) than in eTCD group (8/10 relapse; no patient alive at 1 year). These results support a model in which mature donor T cells in the graft may play a key role, in vivo, in NK cell differentiation by improving NK cell maturation and cytolytic function against leukemic blasts. They point to the dilemma of haploidentical hematopoietic SCT in leukemic patients: on the one hand, extensive T-cell depletion is associated with a risk of fatal leukemia relapse due to the loss of the GvL effect T cells, which can not be replaced by immature NK cells; on the other hand, partial T-cell depletion might increase the risk of GvHD but also improves the GvL effect mediated by NK cells. New treatments infusing mature haploidentical NK cells in leukemic patients should be used to test the efficiency of NK alloreactivity.

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