The Activating KIR2DS2 Gene Influences NK Alloreactivity and NK Repertoire.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 313-313
Author(s):  
Joseph H. Chewning ◽  
Charlotte N. Gudme ◽  
Glenn Heller ◽  
Bo Dupont
Keyword(s):  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Hla Class I ◽  
Myelogenous Leukemia ◽  
Class I ◽  
Cross Linking ◽  
Cell Transplant ◽  
Activating Receptor

Abstract The hematopoietic stem cell transplant (HCT) donor KIR genotype has been correlated with disease-free survival in patients with acute myelogenous leukemia. The Killer Cell Immunoglobulin-like Receptor (KIR) gene family encodes highly homologous pairs of activating and inhibiting receptors, 2DL1–2DS1; 2DL2/3–2DS2; and 3DL1–3DS1. Inhibitory members are known to regulate NK cell function through interactions with HLA Class I antigens. The role of activating KIRs and their ligand specificity is, however, not well defined. The activating receptor, KIR2DS1, is known to bind the HLA-Cw C2 group antigens and we have recently demonstrated a role for this receptor in NK cell allorecognition. In contrast, KIR2DS2 does not bind HLA-Cw C1 group antigens, and a functional role of this receptor even in NK allorecognition has not been established. We now demonstrate, that presence of the activating KIR2DS2 gene in NK donors homozygous for the HLA-KIR ligand group C2 is associated with significant alloreactivity against C1 homozygous target cells (polyclonal NK cells, p=0.006; NK clones, p=0.001). This alloreactivity is mediated by “missing self” on the target and is dominated by “lack of C2 group on target”. The “missing C2” effect was absent, however, in C2 homozygous donors lacking 2DS2 (p=0.99). Only very rare cytotoxic NK clones expressing GL183 (2DL2/3, 2DS2) and with alloreactivity against C1 targets could be generated in vitro from 2DS2-positive, C2 homozygous donors. A majority of these rare GL183-positive clones did not demonstrate inhibitory function against the HLA class I deficient 721.221 transfected with Cw3 (C1-group), and GL183 cross-linking of the clones resulted in increased cytokine production. Thus, KIR2DS2 is an activating receptor in NK clones from C2 homozygous donors, but does not appear to recognize C1 ligand. We next investigated 2DS2 function in donors heterozygous for the C groups (i.e. C1/C2). Analysis of NK cell function in a 2DS2-positive, C1/C2 donor revealed a “missing HLA-KIR ligand” effect for the C2 group. Cytotoxicity by IL2-propagated, polyclonal NK cells and NK clones revealed allocytotoxicity against targets lacking the C2 group (p<0.001). In addition, a repertoire analysis on 138 NK clones generated from this donor revealed a marked increase in the number of EB6 (KIR2DL1/S1)-expressing NK clones (95%) compared to both the fresh (10%–50%) and the IL-2-expanded polyclonal NK repertoire (12%–60%). Additionally, all EB6-expressing clones from this donor were inhibited by the C2 ligand. Subsequent studies in freshly isolated NK cells following activating receptor cross-linking (NKp46, NKG2C, and CD16) or by alloantigen activation demonstrated that the functioning subset of NK cells in this donor predominantly expressed the EB6 receptor. Other inhibitory receptors (e.g. NKG2A, KIR3DL1, and KIR3DL2) did not contribute significantly to the functional subset of NK cells. Presence of 2DS2 in this donor was therefore associated with a “skewing” of the NK repertoire towards EB6 positivity, and dominated by functional NK cells that were inhibited by the “self” C2 ligand. Collectively, these studies provide the first evidence that activating KIR can influence the NK cell repertoire. Furthermore, our studies would indicate that presence of activating KIRs in HCT donors for recipients homozygous HLA-KIR ligands might induce post-transplantation graft versus host NK alloreactivity.

Killer Immunoglobulin Receptor (KIR) Negative NK Cells Exhibit Potent Alloreactivity Against Primary Leukemia Targets When Interrupting MHC Class I Interactions through NKG2A Blockade.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2862-2862
Author(s):  
Robert Godal ◽  
Michelle Gleason ◽  
Valarie McCullar ◽  
Sarah Cooley ◽  
Michael Verneris ◽  
...  
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Lymphoblastic Leukemia ◽  
Significant Proportion ◽  
Myelogenous Leukemia ◽  
Class I ◽  
Dominant Factor ◽  
Class I Mhc ◽  
Immunomagnetic Bead

Abstract Effective therapeutic options are lacking for patients with primary refractory or relapsed acute myelogenous leukemia (AML). We have shown that adoptive transfer of haploidentical NK cells can result in complete remissions (25%) in patients with refractory disease but this procedure is still limited by a high failure rate. Based on the finding that 29±3% (n=26) of normal CD56dim NK cells are KIR− NKG2A+, we hypothesized that non-KIR class I MHC inhibitory receptors may play a bigger role than previously recognized in the cumulative integration of signals that determine whether leukemia targets are killed by NK cells. We studied the role of NKG2A and KIR inhibitory signals on primary AML and acute lymphoblastic leukemia (ALL) targets collected by therapeutic lymphapheresis. Blast susceptibility to fresh resting polyclonal allogeneic NK cells (enriched by CD3 depletion) and to NK cells activated with low pharmacologic doses of IL-2 for 72 hours was determined using flow cytometry based cytotoxicity assays and a degranulation assay using CD107a. The role of inhibitory signaling through class I MHC-recognizing receptors was tested by blocking interactions between receptor and cognate ligand using 1) a pan-MHC monoclonal antibody (mAb) (clone HP17-F) recognizing HLA-A, B, C and E, 2) an anti-KIR reagent (1-7F9 which blocks inhibitory KIR2DL1/L2/L3) currently in clinical trials (Novonordisk, Copenhagen) and 3) a mAb against NKG2A (clone Z199). Susceptibility to killing was defined as >10% lysis at an E:T ratio of 10:1. Two of 8 leukemias (25%) were lysed by resting allogeneic NK cells. NK cells activated with IL-2 (5U/ml) killed 7 of 8 targets (average increase of 13±2.2% lysis). In 3 AMLs killing was significantly enhanced by pan-MHC mAb blockade, but was less enhanced by anti-KIR blockade. NKG2A blockade alone also increased killing, and when added to anti-KIR blockade AML killing was equal to that obtained with MHC blockade. This suggests that non-KIR class I recognizing interactions were operant. Interestingly, anti-KIR blockade did significantly enhance killing of ALL targets suggesting that higher MHC expression (MFI 3-fold greater) may be a dominant factor to NK cell susceptibility in ALL. These findings support the notion that susceptibility to NK cell lysis is determined by interactions beyond just KIR and KIR-ligands. To explore this further KIR− NK cells were enriched with immunomagnetic bead separation (80% NKG2A+). AML target killing by these IL-2 activated KIR−NKG2A+ NK cells increased significantly after pan-MHC and NKG2A blockade (from an average baseline of 21% lysis to 34% for both), but no increase was seen with KIR blockade. This suggests that a significant proportion of normal NK cells are negatively regulated by KIR-independent mechanisms interacting with HLA-E. In summary, interrupting dominant NK cell receptor interactions with class I MHC ligands may lead to better strategies to treat AML and even ALL. NKG2A blockade may be a good target as it is highly expressed on virtually all NK cells reconstituting in the first 3 months after allogeneic HCT and it identifies NK cells with effector function in normal subjects (Cooley et al, Blood110:5782007). The combination of inhibitory signal blockade with other activators such as low dose IL-2 or mAb capable of ADCC may be needed to best exploit the clinical therapeutic potential of NK cells.

scholarly journals Cross-linking of MHC class I molecules on human NK cells inhibits NK cell function, segregates MHC I from the NK cell synapse, and induces intracellular phosphotyrosines

2004 ◽  
Vol 76 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Gonzalo Rubio ◽  
Xavier Férez ◽  
María Sánchez-Campillo ◽  
Jesús Gálvez ◽  
Salvador Martí ◽  
...  
Keyword(s):  
Nk Cells ◽  
Mhc Class I ◽  
Cell Function ◽  
Nk Cell ◽  
Class I ◽  
Cross Linking ◽  
Mhc I ◽  
Cell Synapse ◽  
Mhc Class I Molecules

scholarly journals Strategies to activate NK cells to prevent relapse and induce remission following hematopoietic stem cell transplantation

Blood ◽  
2018 ◽  
Vol 131 (10) ◽  
pp. 1053-1062 ◽  
Author(s):  
Sarah Cooley ◽  
Peter Parham ◽  
Jeffrey S. Miller
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Checkpoint Inhibitors ◽  
Killer Cell ◽  
Hla Class I ◽  
Class I ◽  
Survival Strategies ◽  
Immune Memory ◽  
Cell Transplant ◽  
Hematopoietic Stem

Abstract Natural killer (NK) cells are lymphocytes of innate immunity that respond to virus infected and tumor cells. After allogeneic transplantation, NK cells are the first reconstituting lymphocytes, but are dysfunctional. Manipulating this first wave of lymphocytes could be instrumental in reducing the 40% relapse rate following transplantation with reduced-intensity conditioning. NK cells express numerous activating and inhibitory receptors. Some recognize classical or nonclassical HLA class I ligands, others recognize class I–like ligands or unrelated ligands. Dominant in the NK-cell transplant literature are killer cell immunoglobulin-like receptors (KIRs), encoded on chromosome 19q. Inhibitory KIR recognition of the cognate HLA class I ligand is responsible for NK-cell education, which makes them tolerant of healthy cells, but responsive to unhealthy cells having reduced expression of HLA class I. KIR A and KIR B are functionally distinctive KIR haplotype groups that differ in KIR gene content. Allogeneic transplant donors having a KIR B haplotype and lacking a recipient HLA-C epitope provide protection against relapse from acute myeloid leukemia. Cytomegalovirus infection stimulates and expands a distinctive NK-cell population that expresses the NKG2C receptor and exhibits enhanced effector functions. These adaptive NK cells display immune memory and methylation signatures like CD8 T cells. As potential therapy, NK cells, including adaptive NK cells, can be adoptively transferred with, or without, agents such as interleukin-15 that promote NK-cell survival. Strategies combining NK-cell infusions with CD16-binding antibodies or immune engagers could make NK cells antigen specific. Together with checkpoint inhibitors, these approaches have considerable potential as anticancer therapies.

Decidual natural-killer-cell interaction with trophoblast: cytolysis or cytokine production?

2000 ◽  
Vol 28 (2) ◽  
pp. 196-198 ◽  
Author(s):  
Y. W. Loke ◽  
A. King
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Cell Function ◽  
Nk Cell ◽  
Close Contact ◽  
Killer Cell ◽  
Hla Class I ◽  
Class I ◽  
Target Cells ◽  
Hla Class I Antigens

At the implantation site, the uterine mucosa (decidua) is infiltrated by large numbers of natural killer (NK) cells. These NK cells are in close contact with the invading fetal trophoblast and we have proposed that they might be the effector cells that control the implantation of the allogeneic placenta. Recent characterization of NK cell receptors and their HLA class I ligands has suggested potential mechanisms by which NK cells might interact with trophoblast. However, what happens as a result of this interaction is not clear. The traditional method for investigating NK cell function in vitro is the protection from lysis of target cells by expression of HLA class I antigens. This might not be an accurate reflection of what happens in vivo. Another function of NK cells is the production of cytokines on contact with target cells. This could be an important outcome of the interaction between decidual NK cells and trophoblast. Decidual NK cells are known to produce a variety of cytokines; trophoblast cells express receptors for many of these cytokines, indicating that they can potentially respond. In this way, decidual NK cells have a significant influence on trophoblast behaviour during implantation.

scholarly journals ERAP1 Controls the Interaction of the Inhibitory Receptor KIR3DL1 With HLA-B51:01 by Affecting Natural Killer Cell Function

2021 ◽  
Vol 12 ◽  
Author(s):  
Silvia D’Amico ◽  
Valerio D’Alicandro ◽  
Mirco Compagnone ◽  
Patrizia Tempora ◽  
Giusy Guida ◽  
...  
Keyword(s):  
Mhc Class I ◽  
Cell Function ◽  
Nk Cell ◽  
Killer Cell ◽  
Cell Subset ◽  
Human Tumor ◽  
Hla Class I ◽  
Class I ◽  
Pharmacological Inhibition ◽  
Mhc Class I Molecules

The endoplasmic reticulum aminopeptidase ERAP1 regulates innate and adaptive immune responses by trimming peptides for presentation by major histocompatibility complex (MHC) class I molecules. Previously, we have shown that genetic or pharmacological inhibition of ERAP1 on murine and human tumor cell lines perturbs the engagement of NK cell inhibitory receptors Ly49C/I and Killer-cell Immunoglobulin-like receptors (KIRs), respectively, by their specific ligands (MHC class I molecules), thus leading to NK cell killing. However, the effect of ERAP1 inhibition in tumor cells was highly variable, suggesting that its efficacy may depend on several factors, including MHC class I typing. To identify MHC class I alleles and KIRs that are more sensitive to ERAP1 depletion, we stably silenced ERAP1 expression in human HLA class I-negative B lymphoblastoid cell line 721.221 (referred to as 221) transfected with a panel of KIR ligands (i.e. HLA-B*51:01, -Cw3, -Cw4 and -Cw7), or HLA-A2 which does not bind any KIR, and tested their ability to induce NK cell degranulation and cytotoxicity. No change in HLA class I surface expression was detected in all 221 transfectant cells after ERAP1 depletion. In contrast, CD107a expression levels were significantly increased on NK cells stimulated with 221-B*51:01 cells lacking ERAP1, particularly in the KIR3DL1-positive NK cell subset. Consistently, genetic or pharmacological inhibition of ERAP1 impaired the recognition of HLA-B*51:01 by the YTS NK cell overexpressing KIR3DL1*001, suggesting that ERAP1 inhibition renders HLA-B*51:01 molecules less eligible for binding to KIR3DL1. Overall, these results identify HLA-B*51:01/KIR3DL1 as one of the most susceptible combinations for ERAP1 inhibition, suggesting that individuals carrying HLA-B*51:01-like antigens may be candidates for immunotherapy based on pharmacological inhibition of ERAP1.

scholarly journals The Ly-49D Receptor Activates Murine Natural Killer Cells

1996 ◽  
Vol 184 (6) ◽  
pp. 2119-2128 ◽  
Author(s):  
L.H. Mason ◽  
S.K. Anderson ◽  
W.M. Yokoyama ◽  
H.R.C. Smith ◽  
R. Winkler-Pickett ◽  
...  
Keyword(s):  
Gene Family ◽  
Nk Cells ◽  
Natural Killer ◽  
Cell Function ◽  
Nk Cell ◽  
Cell Subset ◽  
Class I ◽  
Target Cells ◽  
Color Flow ◽  
Functional Capabilities

Proteins encoded by members of the Ly-49 gene family are predominantly expressed on murine natural killer (NK) cells. Several members of this gene family have been demonstrated to inhibit NK cell lysis upon recognizing their class I ligands on target cells. In this report, we present data supporting that not all Ly-49 proteins inhibit NK cell function. Our laboratory has generated and characterized a monoclonal antibody (mAb) (12A8) that can be used to recognize the Ly-49D subset of murine NK cells. Transfection of Cos-7 cells with known members of the Ly-49 gene family revealed that 12A8 recognizes Ly-49D, but also cross-reacts with the Ly-49A protein on B6 NK cells. In addition, 12A8 demonstrates reactivity by both immunoprecipitation and two-color flow cytometry analysis with an NK cell subset that is distinct from those expressing Ly-49A, C, or G2. An Ly-49D+ subset of NK cells that did not express Ly49A, C, and G2 was isolated and examined for their functional capabilities. Tumor targets and concanovalin A (ConA) lymphoblasts from a variety of H2 haplotypes were examined for their susceptibility to lysis by Ly-49D+ NK cells. None of the major histocompatibility complex class I–bearing targets inhibited lysis of Ly-49D+ NK cells. More importantly, we demonstrate that the addition of mAb 12A8 to Ly-49D+ NK cells can augment lysis of FcγR+ target cells in a reverse antibody-dependent cellular cytotoxicity–type assay and induces apoptosis in Ly49D+ NK cells. Furthermore, the cytoplasmic domain of Ly-49D does not contain the V/IxYxxL immunoreceptor tyrosine-based inhibitory motif found in Ly-49A, C, or G2 that has been characterized in the human p58 killer inhibitory receptors. Therefore, Ly-49D is the first member of the Ly-49 family characterized as transmitting positive signals to NK cells, rather than inhibiting NK cell function.

Molecular analysis of the methylprednisolone-mediated inhibition of NK-cell function: evidence for different susceptibility of IL-2– versus IL-15–activated NK cells

Blood ◽  
2007 ◽  
Vol 109 (9) ◽  
pp. 3767-3775 ◽  
Author(s):  
Laura Chiossone ◽  
Chiara Vitale ◽  
Francesca Cottalasso ◽  
Sara Moretti ◽  
Bruno Azzarone ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Surface Expression ◽  
Steroid Treatment ◽  
Cross Linking ◽  
Target Cells ◽  
Activating Receptors ◽  
And Function ◽  
Nk Cytotoxicity

Abstract Steroids have been shown to inhibit the function of fresh or IL-2–activated natural killer (NK) cells. Since IL-15 plays a key role in NK-cell development and function, we comparatively analyzed the effects of methylprednisolone on IL-2– or IL-15–cultured NK cells. Methylprednisolone inhibited the surface expression of the major activating receptors NKp30 and NKp44 in both conditions, whereas NK-cell proliferation and survival were sharply impaired only in IL-2–cultured NK cells. Accordingly, methylprednisolone inhibited Tyr phosphorylation of STAT1, STAT3, and STAT5 in IL-2–cultured NK cells but only marginally in IL-15–cultured NK cells, whereas JAK3 was inhibited under both conditions. Also, the NK cytotoxicity was similarly impaired in IL-2– or IL-15–cultured NK cells. This effect strictly correlated with the inhibition of ERK1/2 Tyr phosphorylation, perforin release, and cytotoxicity in a redirected killing assay against the FcRγ+ P815 target cells upon cross-linking of NKp46, NKG2D, or 2B4 receptors. In contrast, in the case of CD16, inhibition of ERK1/2 Tyr phosphorylation, perforin release, and cytotoxicity were not impaired. Our study suggests a different ability of IL-15–cultured NK cells to survive to steroid treatment, thus offering interesting clues for a correct NK-cell cytokine conditioning in adoptive immunotherapy.

scholarly journals Specificity of HLA class I antigen recognition by human NK clones: evidence for clonal heterogeneity, protection by self and non-self alleles, and influence of the target cell type.

1993 ◽  
Vol 178 (4) ◽  
pp. 1321-1336 ◽  
Author(s):  
V Litwin ◽  
J Gumperz ◽  
P Parham ◽  
J H Phillips ◽  
L L Lanier
Keyword(s):  
Nk Cells ◽  
Mhc Class I ◽  
Target Cell ◽  
Nk Cell ◽  
Hla Class I ◽  
Class I ◽  
Target Cells ◽  
Clonal Heterogeneity ◽  
Multiple Alleles ◽  
Wide Range

Prior studies using polyclonal populations of natural killer (NK) cells have revealed that expression of certain major histocompatibility complex (MHC) class I molecules on the membrane of normal and transformed hematopoietic target cells can prevent NK cell-mediated cytotoxicity. However, the extent of clonal heterogeneity within the NK cell population and the effect of self versus non-self MHC alleles has not been clearly established. In the present study, we have generated more than 200 independently derived human NK cell clones from four individuals of known human histocompatibility leukocyte antigens (HLA) type. NK clones were analyzed for cytolytic activity against MHC class I-deficient Epstein Barr virus (EBV) transformed B lymphoblastoid cell lines (B-LCL) stably transfected with several HLA-A, -B, or -C genes representing either self or non-self alleles. All NK clones killed the prototypic HLA-negative erythroleukemia K562 and most lysed the MHC class I-deficient C1R and 721.221 B-LCL. Analysis of the panel of HLA-A, -B, and -C transfectants supported the following general conclusions. (a) Whereas recent studies have suggested that HLA-C antigens may be preferentially recognized by NK cells, our findings indicate that 70% or more of all NK clones are able to recognize certain HLA-B alleles and many also recognize HLA-A alleles. Moreover, a single NK clone has the potential to recognize multiple alleles of HLA-A, HLA-B, and HLA-C antigens. Thus, HLA-C is not unique in conferring protection against NK lysis. (b) No simple patterns of HLA specificity emerged. Examination of a large number of NK clones from a single donor revealed overlapping, yet distinct, patterns of reactivity when a sufficiently broad panel of HLA transfectants was examined. (c) Both autologous and allogeneic HLA antigens were recognized by NK clones. There was neither evidence for deletion of NK clones reactive with self alleles nor any indication for an increased frequency of NK clones recognizing self alleles. (d) With only a few exceptions, protection conferred by transfection of HLA alleles into B-LCL was usually not absolute. Rather a continuum from essentially no protection for certain alleles (HLA-A*0201) to very striking protection for other alleles (HLA-B*5801), with a wide range of intermediate effects, was observed. (e) Whereas most NK clones retained a relatively stable HLA specificity, some NK clones demonstrated variable and heterogeneous activity over time. (f) NK cell recognition and specificity cannot be explained entirely by the presence or absence of HLA class I antigens on the target cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Leukemia Activity of Alloreactive NK Cells in Haploidentical HSCT in Pediatric Patients: Re-Defining the Role of Activating and Inhibitory KIR

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3002-3002 ◽  
Author(s):  
Daniela Pende ◽  
Stefania Marcenaro ◽  
Michela Falco ◽  
Stefania Martini ◽  
Maria Ester Bernardo ◽  
...  
Keyword(s):  
T Cell ◽  
Nk Cells ◽  
Nk Cell ◽  
Cell Subset ◽  
Hla Class I ◽  
Class I ◽  
Leukemia Cells ◽  
Hla Alleles ◽  
Time Points ◽  
Selection Of

Abstract T-cell depleted hematopoietic stem cell transplantation from haploidentical donors (haplo-HSCT) has been reported to benefit from the graft-versus-leukemia effect mediated by natural killer (NK) cells when donor displays NK alloreactivity versus the recipient. NK alloreactivity is mediated by NK receptors, namely Killer Ig-like receptors (KIR) which are specific for allotypic determinants that are shared by different HLA-class I alleles (referred to as KIR ligands). It is known that KIR2DL1 recognizes HLA-C alleles characterized by Lys at position 80 (C2 group), KIR2DL2/3 recognize HLA-C alleles characterized by Asn at position 80 (C1 group), KIR3DL1 recognizes HLA-B alleles sharing the Bw4 supertypic specificity (Bw4 group) and KIR3DL2 recognizes HLA-A3 and –A11 alleles. KIR2D/3DL are inhibitory receptors that, upon engagement with the cognate ligand, inhibit lysis. Activating KIRs, highly homologous in the extracellular domain to the inhibitory counterparts, are KIR2DS1, KIR2DS2 and KIR3DS1, but only KIR2DS1 has been shown to specifically recognize C2 group of alleles expressed on B-EBV cells. We analyzed 21 children with leukemia receiving haplo-HSCT from a relative after a myeloablative conditioning regimen; in all pairs, the expression of a given KIR ligand (HLA class I allele) of the donor was missing in the patient (i.e. KIR ligand-mismatched haplo-HSCT). T-cell depletion was performed through positive selection of CD34+ cells; no pharmacological immune suppression was employed after HSCT. KIR genotype of all donors was evaluated to detect the presence of the various inhibitory and activating KIR genes. Phenotypic analyses were performed on NK cells derived from the donor and the patient at different time points after HSCT. Thanks to the availability of new mAbs able to discriminate between the inhibitory and the activating forms of a certain KIR, we could identify the alloreactive NK cell subset at the population level. These alloreactive NK cells express the KIR specific for the KIR ligand-mismatch (permissive inhibitory KIR) and the activating KIR (if present), while they do not express all inhibitory KIR specific for the patient HLA alleles and NKG2A. Thus, in most instances, we could precisely identify the size of the alloreactive NK cell subset in the donor and in the reconstituted repertoire of the recipient. Functional assays were performed to assess alloreactivity, using appropriate B-EBV cell lines and, if available, patient’s leukemia blasts. In some cases, also NK cell clones were extensively studied, for phenotype and receptor involvement in killing activity. We found that, in most transplanted patients, variable proportions of donor-derived alloreactive NK cells displaying anti-leukemia activity were generated and maintained even at late time-points after transplantation. Donor-derived KIR2DL1+ NK cells isolated from the recipient displayed the expected capability of selectively killing C1/C1 target cells, including patient leukemia blasts. Differently, KIR2DL2/3+ NK cells displayed poor alloreactivity against leukemia cells carrying HLA alleles belonging to the C2 specificity. Unexpectedly, this was due to recognition of C2 by KIR2DL2/3, as revealed by receptor blocking experiments and by binding assays of soluble KIR to HLA-C transfectants. Remarkably, however, C2/C2 leukemia blasts were killed by KIR2DL2/3+ (or by NKG2A+) NK cells that co-expressed KIR2DS1. This could be explained by the ability of KIR2DS1 to directly recognize C2 on leukemia cells. A role for the KIR2DS2 activating receptor in leukemia cell lysis could not be established. Taken together, these findings provide new information on NK alloreactivity in haplo-HSCT that may greatly impact on the selection of the optimal donor.

HLA Influence on NK Cell Expansion

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4924-4924
Author(s):  
Jennifer Schellekens ◽  
Anna Stserbakova ◽  
Madis Tõns ◽  
Hele Everaus ◽  
Marcel GJ Tilanus ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Lines ◽  
Cell Expansion ◽  
Nk Cell ◽  
Killer Cell ◽  
Hla Class I ◽  
Class I ◽  
Haematopoietic Stem Cell ◽  
Specific Priming

Abstract Natural Killer (NK) cells are effector cells in the innate immune system. The anti-leukaemic capacities of NK cells in haematopoietic stem cell transplantation make these cells a potential treatment modality to improve clinical outcome. Immunotherapy with NK cells requires transfusion of large quantities, which obviates the need for an in vitro culture system for NK cells. The killer cell immunoglobulin-like receptors (KIR) on NK cells recognise defined groups of HLA class I alleles. To elucidate the influence of these interactions on proliferation, the peripheral blood mononuclear cells (PBMCs) of 29 patients and donors were cultured in CellGro SCGM with IL-2 and OKT3 antibody to expand the NK cell fraction. The killer cell immunoglobulin-like receptor (KIR) and HLA repertoire were determined by sequence specific priming and sequence based typing respectively. The percentage of NK cell expansion from the total PBMC fraction varied between 5.4% and 71.6%. A significantly better NK cell expansion was observed for individuals homozygous for HLA-C epitope group 2 (p&lt;0.05). For evaluation of cytolytic competence of the cultured NK cells, specific killing of an HLA class I expression deficient LCL 721.221 cell line and three 721.221 cell lines transfected with different HLA-C alleles was determined. A significantly better NK cell-induced specific cytotoxicity was observed towards the untransfected 721.221 cells compared to the HLA-C transfected 721.221 cells. No significant differences were observed between killing of the three HLA-C transfected 721.221 cell lines. We have shown that cytolytic capacities of the cultured NK cells are maintained and in vitro expansion of NK cells is dependant on the presence of HLA-C alleles.

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