Accumulating evidence has shown that allogeneic blood transfusions can induce significant immunosuppression in recipients, and thereby increase the risk of postoperative infection and/or tumor relapse. Although it is well known that natural killer (NK) cells are responsible for the immunodepression effects of transfusion, the underlying mechanisms remain obscure. In this study, we investigated the role of NK cells in transfusion-induced immunodepression in β-thalassemia major. The proportion of circulating NK cells and the expression of NK receptors (NKG2A, CD158a, NKP30, NKP46 and NKG2D) as well as CD107a were detected by multicolor flow cytometry. IFN-γ production by circulating NK cells was detected by intracellular cytokine staining. Our results showed that the proportion and cytotoxicity (CD107a expression) of circulating NK cells in transfusion-dependent β-thalassemia major patients were remarkably lower than those of β-thalassemia minor patients or healthy volunteers. Expression of NKG2A inhibitory receptor on circulating NK cells in patients with β-thalassemia major was remarkably up-regulated, but there were no significant differences in the expression levels of NKP30, NKP46, NKG2D, CD158a and IFN-γ. These results indicate NKG2A inhibitory receptor may play a key role in transfusion-induced immunodepression of NK cells in patients with β-thalassemia major.
Adolescent ; Child ; Female ; Flow Cytometry ; Gene Expression Regulation ; Humans ; Immunosuppression ; Killer Cells, Natural ; immunology ; metabolism ; Male ; NK Cell Lectin-Like Receptor Subfamily C ; blood ; immunology ; NK Cell Lectin-Like Receptor Subfamily K ; blood ; immunology ; Natural Cytotoxicity Triggering Receptor 1 ; blood ; immunology ; Natural Cytotoxicity Triggering Receptor 3 ; blood ; immunology ; Receptors, KIR2DL1 ; blood ; immunology ; Transfusion Reaction ; beta-Thalassemia ; blood ; immunology ; pathology

CD94/NKG2A is a kind of inhibitory receptor belonging to C-type lectin superfamily. It specifically expresses on the surface of some lymphocytes such as NK cells and T cells, and mediates inhibitory signal. In this mini-review, the structure of CD94/NKG2A molecule is described and its biological significance is discussed.
Antigens, CD ; immunology ; HLA Antigens ; immunology ; Histocompatibility Antigens Class I ; immunology ; Humans ; Killer Cells, Natural ; immunology ; Lectins, C-Type ; immunology ; NK Cell Lectin-Like Receptor Subfamily C ; NK Cell Lectin-Like Receptor Subfamily D ; Receptors, Immunologic ; immunology ; Receptors, Natural Killer Cell ; T-Lymphocytes ; immunology

NK cell has antigen-non-specific receptors on its surface. Based on the molecular structure, NK cell receptors can be divided into two types, including Ig superfamily and C-type lectin superfamily. Based on function, NK cell receptors can be divided into activation receptors (NKAR) and inhibition receptors (NKIR). NKAR includes CD16 mediating antibody dependent cytotoxicity, NKR-P1 mediating natural cytotoxicity, KAR conjugated with DAP12 and co-stimulatory receptor. They transduce signal through the ITAM motif in their cytoplasmic region. NKIR mainly include KIR and CD94/NKG2. Their ligands are MHC-I molecules. They are closely related to the recognition of auto cells by NK cells. Inhibition of NKAR activation and cytotoxic effect of NK cells by NKIR are carried out through the ITIM motif and require co-aggregation of NKAR and NKIR.
Antigens, CD ; immunology ; Humans ; Immunity, Cellular ; Killer Cells, Natural ; immunology ; Lectins, C-Type ; immunology ; Ligands ; NK Cell Lectin-Like Receptor Subfamily C ; NK Cell Lectin-Like Receptor Subfamily D ; Receptors, IgG ; immunology ; Receptors, Immunologic ; immunology ; Receptors, KIR ; Receptors, Natural Killer Cell

OBJECTIVETo investigate the regulatory effect of IFN-gamma on recognition of target cells by human natural killer (NK) cells.

METHODSThe cytotoxic activity of human NK cell lines (NK92, NKL) was detected by MTT method. Expression of NK cell receptors (NKG2D, NKG2A/B, KIR2DL1 and KIR2DS1) and MICA on target cells (the ligand of NKG2D) was measured by RT-PCR.

RESULTSBoth NK92 and NKL cells exerted higher cytotoxicity to tumor cells with MICA expression, while tumors without MICA expression could resist NK cell lysis. IFN-gamma (> 1000 U/ml) inhibited NK lysis of tumor cells with MICA expression through down-regulating the expression of NKG2D, but up-regulating the expression of NKG2A/B and KIR2DL1.

CONCLUSIONIFN-gamma has a negative effect on activation and cytotoxicity of human NK cells by altering the balance between the expression of activating and inhibitory receptors on NK cells in favor of inhibition. This may serve to limit NK cell over-activation in vivo.

Cell Division ; drug effects ; Cytotoxicity, Immunologic ; drug effects ; Histocompatibility Antigens Class I ; analysis ; physiology ; Humans ; Interferon-gamma ; pharmacology ; Killer Cells, Natural ; immunology ; NK Cell Lectin-Like Receptor Subfamily C ; NK Cell Lectin-Like Receptor Subfamily K ; Receptors, Immunologic ; metabolism ; Receptors, KIR2DL1 ; Receptors, Natural Killer Cell ; Recombinant Proteins ; Tumor Cells, Cultured

This study was aimed to explore the difference of NK cell receptor NKG2D and NKG2A expression on NK cells and CD3(+) T cells and their ligand MHC-I A/B (major histocompatibility complex class I-related chains A/B) and HLA-E expression in leukemia cells, as well as its immunological significance. Flow cytometry was used to detect the killing rate of NK92 cells to 8 leukemia cell lines, and the expression of NKG2D and NKG2A on NK cells and CD3(+) T cells as well as their ligand MHC-I A/B and HLA-E expression on leukemia cells. The results indicated that the NK92 showed different killing activity to different leukemia cell lines. The positive expression rate of NKG2D and NKG2A on NK cells and CD3(+) T cells in ALL patients was no significantly different from that in AML patients (p > 0.05), but positive expression rate of MHC-I A/B and HLA-E in ALL patients was obviously higher than that in AML patients (p < 0.05). It is concluded that there is difference of immune cell function between ALL and AML patients, this difference may be associated with the expression difference of NKG2D and NKG2A ligands on leukemia cells while does not associated with the killing and inhibiting receptors expressed on NK cells and CD3(+) T cells.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; Female ; Histocompatibility Antigens Class I ; genetics ; metabolism ; Humans ; Infant ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Male ; Middle Aged ; NK Cell Lectin-Like Receptor Subfamily C ; genetics ; metabolism ; NK Cell Lectin-Like Receptor Subfamily K ; genetics ; metabolism ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; metabolism ; Young Adult

Antigens, Surface ; analysis ; Antiretroviral Therapy, Highly Active ; CD28 Antigens ; analysis ; CD56 Antigen ; analysis ; HIV Infections ; drug therapy ; immunology ; Humans ; Killer Cells, Natural ; immunology ; Lectins, C-Type ; analysis ; NK Cell Lectin-Like Receptor Subfamily B ; NK Cell Lectin-Like Receptor Subfamily D ; analysis ; Receptors, Immunologic ; analysis ; Receptors, KIR

OBJECTIVETo investigate the expression and possible role of C-type lectin-like natural killer cell receptors, including CD94 and NKG2s, in extranodal NK/T-cell lymphoma, nasal type (EN-NK/T-NT).

METHODSReverse transcriptase polymerase chain reaction (RT-PCR) was used to detect the expression of CD94 and NKG2s in tissue sections of 21 cases of EN-NK/T-NT(confirmed by histology, immunohistochemistry, in-situ hybridization for Epstein-Barr virus(EBV) and PCR for T-cell receptor genes), eight midline B cell lymphomas (BCL), 10 peripheral T cell lymphoma of lymph nodes (PTCL), five spleens, five thymuses and five chronic nasopharyngitis.

RESULTSAll 21 cases of EN-NK/T-NT showed typical histological features, with expression of CD3epsilon, CD56, cytotoxic granules and positivity of EBV in 20 cases. The RT-PCR results showed a high level expression of CD94 (85.7%) and NKG2 members (95.2% totally, with NKG2A/2B in 85.7%, NKG2D in 61.9%, NKG2F in 14.3%, NKG2C/2E in 4.8%, respectively and sequentially) in EN-NK/T-NT. But in the controls, none of the receptors were detected in TCL (0%) and BCL (0%), while only a few cases of lymphoid tissues expressed one or two of these receptors (two spleens and two chronic nasopharyngitis mucosa for CD94, one spleen for NKG2A/2B and one thymus for NKG2D). The differences of CD94 and NKG2 expression between EN-NK/T-NT and BCL or TCL were statistically significant (P<0.01). Co-expression of CD94 and NKG2 was found in 17 out of 21 EN-NK/T-NT cases (81.0%).

CONCLUSIONSThe specific and sequential expression nature of CD94 and NKG2 in EN-NK/T-NT, mimics the developmental expression model in their normal counterparts, and suggests that the tumor cells of most cases are being activated and keeping in a stage as the functional NK cells. Detection of these molecules may provide a useful tool to confirm the diagnosis of NK cell lymphoma.

Adolescent ; Adult ; Aged ; Diagnosis, Differential ; Epstein-Barr Virus Infections ; virology ; Female ; Follow-Up Studies ; Herpesvirus 4, Human ; isolation & purification ; Humans ; Lymphoma, B-Cell ; metabolism ; pathology ; Lymphoma, Extranodal NK-T-Cell ; diagnosis ; metabolism ; pathology ; virology ; Lymphoma, T-Cell, Peripheral ; metabolism ; pathology ; Male ; Middle Aged ; NK Cell Lectin-Like Receptor Subfamily C ; metabolism ; NK Cell Lectin-Like Receptor Subfamily D ; metabolism ; Nose Neoplasms ; diagnosis ; metabolism ; pathology ; virology ; Survival Rate ; Young Adult

OBJECTIVETo observe the effect of Ly49A transfected mouse spleen cells on graft versus host disease (GVHD) and graft versus leukemia (GVL) effect after haploidentical allogeneic bone marrow transplantation in mice.

METHODSLy49A gene was transfected into spleen cells of C57BL/6 mice by retrovirus and the expression rate of Ly49A receptor was evaluated by flow cytometry. The murine model of haploidentical allogeneic acute GVHD was established by using C57BL/6(H - 2b) mouse as donor, and (BALB/c x C57BL/6) F1(H - 2d/b) (CB(6)F(1)) mouse as the recipient which was injected EL9611 cells before transplantation. After irradiation (TBI, (60)Co 10.5 Gy), the recipient received mixed graft of spleen cells and bone marrow cells to establish a GVHD model. The effects of Ly49A transfected spleen cells on GVHD and GVL post haploidentical allogeneic bone marrow transplantation were detected with this model.

RESULTSThe expression rate of Ly49A receptor was (42.20 +/- 4.87)%, (18.67 +/- 2.48)% and (18.73 +/- 3.82)% for pLXSN-Ly49A, pLXSN transfected and untransfected spleen cells respectively. Among haploidentical allo-BMT (C57BL/6(H - 2b)-->CB6F1(H - 2d/b)) groups, the survival time was (7.80 +/- 3.36) days for irradiation group; (21.70 +/- 2.87) days for cyclophosphomide therapy group; (29.40 +/- 6.43) days for mixed bone marrow cells and spleen cells transplantation group; (29.10 +/- 7.39) days for mixed bone marrow cells and pLXSN transfected spleen cells transplantation group and (45.00 +/- 12.38) days for mixed bone marrow cells and Ly49A transfected spleen cells transplantation group, which was much longer than that of any other groups (P = 0.000).

CONCLUSIONThe Ly49A transfected spleen cell transplantation could alleviate GVHD and retain GVL effect in the acute GVHD model post haploidentical allo-BMT.

Animals ; Antigens, Ly ; genetics ; immunology ; Bone Marrow Transplantation ; Cell Transplantation ; adverse effects ; Female ; Graft vs Host Disease ; etiology ; immunology ; mortality ; Graft vs Leukemia Effect ; immunology ; Lectins, C-Type ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; NK Cell Lectin-Like Receptor Subfamily A ; Receptors, NK Cell Lectin-Like ; Spleen ; cytology ; metabolism ; Survival Rate ; Time Factors ; Transfection

BACKGROUNDNatural killer (NK) cells play critical roles in host immune defense, while the quantities and subset distributions may vary among different races. To address the difference, we compared these variables among Chinese Han, the Caucasians and the Blacks. The study may provide critical background information for both basic research and clinical investigation.

METHODSBlood samples collected from populations of different races were tested within 12 hours after collection and subsets of NK cells were characterized using flow cytometry.

RESULTSThe absolute NK count in the Chinese Han was significantly higher than that in the Caucasian. The Han and Caucasian groups showed higher percentages of cytotoxic subset compared to that of the Black group. The percentage of cytokine-producing subset of Chinese Han group was lower than that of Caucasian and Black groups. Black group had a higher percentage of function-unknown NK subset than that of the Han and Caucasian groups.

CONCLUSIONOur data indicated that NK cell count and the distribution of different subsets varied among different races, which should be taken into consideration in related investigations.

Adult ; African Continental Ancestry Group ; Asian Continental Ancestry Group ; European Continental Ancestry Group ; Female ; Humans ; Killer Cells, Natural ; cytology ; metabolism ; Male ; NK Cell Lectin-Like Receptor Subfamily C ; metabolism

OBJECTIVETo observe the effects on antitumor activity of mouse NK cells and the mixed lymphocyte reaction with blocking the interaction between the inhibitory Ly49 receptor on mouse NK cell and MHC-I molecules on target cells with monoclonal antibody.

METHODSNK cells were isolated from splenocytes of C57BL/6J mouse with immunomagnetic method. YAC-1 and M1 cells were used as target cells, the cytotoxicity of NK cells was examined with mixed lymphocyte reaction before and after treatment of anti-Ly49 monoclonal antibody.

RESULTThe cytotoxicity of NK cells to M1 cell was significantly augmented (10.7% +/- 0.5% compared with 84.4 % +/- 2.9%), and the clone-forming capacity of M1 cell was inhibited remarkably (8.2 % +/- 2.2% compared with 94.0% +/- 3.3%) with the increase of concentration of the antibody (0 approximate, equals 60 microg/ml) (P <0.05). The difference of cytotoxicity to YAC-1 cells was only found between 0 microg/ml and 60 microg/ml groups (P <0.05). In mixed lymphocyte reaction, after pretreated with antibody, the proliferation of splenocytes of BALB/C mouse was inhibited (0.398 +/-0.025 compared with 0.128 +/- 0.014), and statistical difference was observed only between antibody groups of 0 microg/ml and 60 microg/ml (P<0.05).

CONCLUSIONBlocking the inhibitory Ly49 receptor on NK cells with monoclonal antibody augments the cytotoxicity to target cells.

Animals ; Antibodies, Monoclonal ; immunology ; pharmacology ; Cell Proliferation ; Cells, Cultured ; Female ; Genes, MHC Class I ; Killer Cells, Natural ; immunology ; Lymphocyte Culture Test, Mixed ; Lymphoma ; immunology ; pathology ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; NK Cell Lectin-Like Receptor Subfamily A ; immunology ; Spleen ; cytology ; immunology