microRNA对自然杀伤细胞发育及功能调控的研究进展

自然杀伤(natural killer,NK)细胞作为重要的固有免疫细胞,在抗病毒和抗肿瘤机制中发挥重要作用。NK细胞的发育和激活受多种细胞因子和表面受体的调控。目前对NK细胞发育、成熟及功能的研究从转录水平逐渐进展到转录后水平。微小RNA(micro RNA,mi RNA)作为一种非编码小RNA在转录后调控机制中发挥作用。近些年研究表明,mi RNA可在转录后水平调控NK细胞发育、成熟及功能,并在不同疾病中发挥不同的调控作用。本文对目前mi RNA在NK细胞发育过程及功能调控中的作用进行综述。     

Interaction of C-type lectin-like receptors NKp65 and KACL facilitates dedicated immune recognition of human keratinocytes

Many well-known immune-related C-type lectin-like receptors (CTLRs) such as NKG2D, CD69, and the Ly49 receptors are encoded in the natural killer gene complex (NKC). Recently, we characterized the orphan NKC gene CLEC2A encoding for KACL, a further member of the human CLEC2 family of CTLRs. In contrast to the other CLEC2 family members AICL, CD69, and LLT1, KACL expression is mostly restricted to skin. Here we show that KACL is a non–disulfide-linked homodimeric surface receptor and stimulates cytotoxicity by human NK92MI cells. We identified the corresponding activating receptor on NK92MI cells that is encoded adjacently to the CLEC2A locus and binds KACL with high affinity. This CTLR, termed NKp65, stimulates NK cytotoxicity and release of proinflammatory cytokines upon engagement of cell-bound KACL. NKp65, a distant relative of the human activating NK receptor NKp80, possesses an amino-terminal hemITAM that is required for NKp65-mediated cytotoxicity. Finally, we show that KACL expression is mainly restricted to keratinocytes. Freshly isolated keratinocytes express KACL and are capable of stimulating NKp65-expressing cells in a KACL-dependent manner. Thus, we report a unique NKC-encoded receptor-ligand system that may fulfill a dedicated function in the immunobiology of human skin.     

Association of natural killer cell immune recovery with a graft-versus-leukemia effect independent of graft-versus-host disease following allogeneic bone marrow transplantation

 There is good evidence that T lymphocytes play an important role in the graft-versus-leukemia (GVL) effect following allogeneic bone marrow transplantation (BMT) for hematologic malignancies. However, the role of natural killer (NK) cells in GVL is less clear. To further investigate a possible association of NK cells with GVL we studied 15 patients undergoing BMT for chronic myeloid leukemia (CML), correlating T-cell (CD4+ and CD8+) and NK-cell (CD16+56+) recovery with relapse and graft-versus-host disease (GVHD). Patients were studied on three occasions up to 9 months after BMT, for lymphocyte surface phenotype and for spontaneous and IL-2-stimulated (LAK cell) cytotoxic function. Circulating CD8+ and NK but not CD4+ cell numbers were significantly lower in five patients who relapsed compared with those remaining in remission after BMT (mean 0.03 vs 0.32×10⁹/l, p=0.002 for CD8+ cells; mean 0.03 vs 0.11×10⁹/l, p=0.002 for NK cells). There was no correlation of CD4+, CD8+, or NK cell numbers and development of grade-II or more acute GVHD. Spontaneous NK cytotoxic function rose to within the normal range in the first month after BMT. LAK function remained low during the study period. These results link NK cell recovery more closely with a GVL than with a GVH effect. Received: 1 May 1996/Accepted: 19 September 1996     

Lack of association between childhood common acute lymphoblastic leukaemia and an HLA-C locus dimorphism influencing the specificity of natural killer cells

Previous serological studies documenting an association between acute lymphoblastic leukaemia (ALL) and HLA-Cw antigens suggested that the HLA-C locus might influence susceptibility to ALL. However, associations with more than one Cw antigen suggest that polymorphic variants shared by more than Cw allele could be involved. Recent studies have shown that the HLA-C locus encodes two ligands (NK1 and NK2) recognized by receptors on natural killer (NK) cells. HLA-Cw alleles encoding these ligands are dimorphic, dependent on whether they encode one or other NK ligand. To determine whether susceptibility to the common (CD10⁺) form of childhood ALL (c-ALL) is associated with NK1 or NK2, we carried out a molecular analysis of 94 childhood c-ALL patients and 136 infant controls. We found no difference in the frequency of NK1 and NK2 alleles, phenotypes or genotypes between the patients and controls, suggesting that this does not explain the role of the HLA-C locus in susceptibility to childhood c-ALL.