Clonal nature of mast-cell clusters formed in W/Wv mice after bone marrow transplantation.

We have recently found that the number of mast cells in the skin of adult W/Wv mice is less than 1% of that observed in congeneic +/+ mice, and that no mast cells are detected in other tissues of W/Wv mice. After the transplantation of bone marrow cells from congeneic +/+ mice, the number of mast cells in the skin, stomach, caecum and mesentery of the W/Wv mice increased to levels similar to those of the +/+ mice. Study of the mast-cell number in the W/Wv mice at various times after transplantation suggested to use that mast cells might develop in groups, particularly in the skin and mesentery. In this report, we have attempted to elucidate the possible clonal origin of such mast-cell clusters from a single precursor cell, using giant granules of beige (C57BL/6-bgJ/bgJ, Chediak-Higashi syndrome) mice as a marker to identify the origin of the mast cells (Fig. 1). We found that when WB-W/+xC57BL/6-Wv (WBB6F1)-W/Wv mice were injected with a mixture of bone marrow cells from beige C57BL/6 mice and normal C57BL/6 mice, more than 95% of mast-cell clusters consisted of either beige-type cells alone or normal-type cells alone. We conclude, therefore, that the cluster of mast cells originated from a single precursor cell.     

A cloned cell with NK function resembles basophils by ultrastructure and expresses IgE receptors

Natural killer (NK) cells are defined by their ability to lyse certain tumour cells in vitro without previous exposure to them, and have been postulated as effectors of immune surveillance against spontaneous neoplasms. Because they kill some non-neoplastic lymphoid cells, they may also have a role in immunoregulation. NK cell activity resides in a small proportion of normal mouse spleen cells (less than 5%) that have been difficult to characterize completely. They may represent a heterogeneous group of effector cells whose precise relationship to other myelopoietic or immunological cells has remained obscure. We have previously described a cloned mouse cell line (Cl. Ly 1-2-NK-1+/11) with the functional characteristics of natural killer cells activated by interferon or other factors. We now find that this cloned line, like basophils and mast cells, expresses high-affinity plasma membrane receptors (Fc epsilon R) specific for IgE antibody. In addition, the clone contains cytoplasmic granules similar by ultrastructure to those of basophils of the mouse and other species. Our findings indicate that cells sharing morphological and biochemical features of basophilic granulocytes can mediate NK lysis.     

Induction and kinetics of natural killer cells in humans following interferon therapy

Natural killer (NK) cells are non-B, non-T lymphocytes that effect spontaneous cytolysis of both virus-infected and neoplastically transformed target cells. These NK lymphocytes have been detected in several species including man. Interferon is a primary regulator of natural killer activity. Because NK cells have been implicated in the regulation of tumour cell expression and can be induced by interferon in murine models, we have studied patients receiving large doses of interferon to determine (1) whether interferon could induce NK lymphocytes in the peripheral blood of man, and (2) whether there are characteristic kinetics for the appearance, disappearance and reactivation of NK lymphocytes following interferon therapy. We report here the activation of human NK cells by the systemic inoculation of human subjects with interferon. Five patients received interferon as therapy for non-Hodgkin's lymphoma. All showed a marked increase in NK cell activity 12--24 h after inoculation. Peak NK activity occurred 18 h after introducing interferon, and thereafter declined rapidly but remained above pre-interferon levels. Induced NK activity occurred with reintroduction of interferon but at lower levels of activity and with different kinetics.     

A human natural killer cell subset provides an innate source of IL-22 for mucosal immunity

Natural killer (NK) cells are classically viewed as lymphocytes that provide innate surveillance against virally infected cells and tumour cells through the release of cytolytic mediators and interferon (IFN)-gamma. In humans, blood CD56(dim) NK cells specialize in the lysis of cell targets. In the lymph nodes, CD56(bright) NK cells secrete IFN-gamma cooperating with dendritic cells and T cells in the generation of adaptive responses. Here we report the characterization of a human NK cell subset located in mucosa-associated lymphoid tissues, such as tonsils and Peyer's patches, which is hard-wired to secrete interleukin (IL)-22, IL-26 and leukaemia inhibitory factor. These NK cells, which we refer to as NK-22 cells, are triggered by acute exposure to IL-23. In vitro, NK-22-secreted cytokines stimulate epithelial cells to secrete IL-10, proliferate and express a variety of mitogenic and anti-apoptotic molecules. NK-22 cells are also found in mouse mucosa-associated lymphoid tissues and appear in the small intestine lamina propria during bacterial infection, suggesting that NK-22 cells provide an innate source of IL-22 that may help constrain inflammation and protect mucosal sites.     

Rae1 and H60 ligands of the NKG2D receptor stimulate tumour immunity

Natural killer (NK) cells attack many tumour cell lines, and are thought to have a critical role in anti-tumour immunity; however, the interaction between NK cells and tumour targets is poorly understood. The stimulatory lectin-like NKG2D receptor is expressed by NK cells, activated CD8+ T cells and by activated macrophages in mice. Several distinct cell-surface ligands that are related to class I major histocompatibility complex molecules have been identified, some of which are expressed at high levels by tumour cells but not by normal cells in adults. However, no direct evidence links the expression of these 'induced self' ligands with tumour cell rejection. Here we demonstrate that ectopic expression of the murine NKG2D ligands Rae1beta or H60 in several tumour cell lines results in potent rejection of the tumour cells by syngeneic mice. Rejection is mediated by NK cells and/or CD8+ T cells. The ligand-expressing tumour cells induce potent priming of cytotoxic T cells and sensitization of NK cells in vivo. Mice that are exposed to live or irradiated tumour cells expressing Rae1 or H60 are specifically immune to subsequent challenge with tumour cells that lack NKG2D ligands, suggesting application of the ligands in the design of tumour vaccines.     

Spleen colony-forming cell as common precursor for tissue mast cells and granulocytes

The haematopoietic stem cells which produce colonies in the spleen of irradiated mice (CFU-S) can differentiate into erythrocytes, granulocytes, megakaryocytes and B lymphocytes. Although mast cell precursors are known to be present in the bone marrow, spleen, fetal liver and peripheral blood of mice, the relationship between the mast cell precursor and CFU-S has remained unclear. We have now made use of mice of two mutant genotypes to determine whether or not the tissue mast cell is a progeny of CFU-S. Giant granules of beige (C57BL/6-bg/bg, Chediak-Higashi syndrome) mice can be used for identification of the origin of both tissue mast cells and granulocytes, and WBB6F1-W/Wv mice are useful recipients because they lack tissue mast cells owing to a defect in mast cell precursors. We injected the cells from a single spleen colony into each WBB6F1-W/Wv mouse and demonstrated directly that the tissue mast cell is a progeny of CFU-S.     

Oxygen intermediates are triggered early in the cytolytic pathway of human NK cells

The mechanism of tumour cell destruction by natural killer (NK) cells or other lymphocytes is not understood. NK cells appear to represent a primitive anti-tumour surveillance system more analogous to macrophages than lymphocytes. Free oxygen radicals (O-2, OH) and H2O2 are thought to be involved in cell destruction by macrophages and therefore we looked for similar cytocidal intermediates of oxygen in NK cells. These highly reactive molecular species can easily be detected in the presence of luminol by the emission of light. We show here that highly enriched human NK cells respond to NK-sensitive but not NK-insensitive tumour cells with a rapid burst of oxygen metabolites as detected both by chemiluminescence and cytochrome c reduction. Agents which can prevent chemiluminescence and cytochrome c reduction, such as superoxide dismutase (SOD), reduced NK-mediated cytolysis and agents which increased chemiluminescence, such as interferon, also increased NK-mediated cytolysis. These results suggest that the production of oxygen species may be the earliest event to occur in the NK cell following tumour cell contact, and these products are involved in NK-mediated cytolysis.     

Precursor and effector phenotypes of activated human T lymphocytes

In mice, thymus-derived lymphocytes are differentiated into functional subclasses by their cell surface antigens. The Ly 1 determinants are present on T cells with a helper function, whereas Ly 2 and Ly 3 antigens are expressed on the surface of lymphocytes with suppressor or cytotoxic functions. In man also, T-cell subsets have been identified using allo- and heteroimmune sera and, more recently, using monoclonal antibodies, which seem to identify helper and suppressor or cytotoxic subpopulations. The major histocompatibility system (MHS)-encoded Ia antigens belong to several polymorphic families of membrane associated glycoproteins originally found on B lymphocytes; however, they have also been shown to be markers for suppressor T cells in mice. Recent studies have shown that in both mouse and man, T cells activated by a mixed lymphocyte reaction or by mitogens become Ia+. Furthermore, some human T lymphoid cells, either freshly isolated from peripheral blood or after in vitro activation by lectins or alloantigens, possess suppressor properties. We report here the phenotype of a T suppressor-cell subpopulation which was induced in long-term culture of lymphoid cells after activation with phytohaemagglutinin (PHA). Our results suggest that a subset of T cells was progressively expanded over a period of 8 days in culture and that, with the expression on the surface of these cells of 'Ia-like' antigens, they acquired the capacity to suppress the proliferative response of syngeneic or allogeneic lymphocytes to alloantigens or mitogens.     

CD3-negative natural killer cells express zeta TCR as part of a novel molecular complex

Natural killer (NK) cells are large granular lymphocytes capable of killing tumour cells in a non-MHC restricted manner. NK cells do not express cell-surface CD3, or any known target recognition structure analogous to the T cell antigen receptor (TCR) heterodimers (alpha beta or gamma delta). Consistent with their lack of expression of a CD3-TCR complex, NK cells do not require prior sensitization or antigen presentation by accessory cells to specifically recognize their tumour targets. Although NK cells do not express CD3-TCR, they do express CD2, the target of an alternative activation pathway which is functional in both T cells and NK cells. In T cells, this alternative activation pathway utilizes some component of the CD3-TCR complex as a transducer molecule that is required for mitogenesis. The fact that NK cells are activated by this alternative pathway suggested that they might express a related subunit of the CD3-TCR complex capable of transducing the CD2-mediated signal. Here we show that human NK cells express the zeta-chain of the TCR complex in association with additional structures not included in CD3-TCR.     

T-cell-mediated enhancement of host-versus-graft reactivity in mice fed a diet enriched in vitamin A acetate

Retinol (vitamin A) and some of its derivatives have an important role in: (1) regulating growth, proliferation and differentiation of various tissues and (2) maintaining reproduction and visual function in man and higher animals. Vitamin A and retinoids are also known as potent immunoregulatory and antineoplastic agents. Their ability to increase reactivity to histoincompatible tissues is well documented but the mechanism of this action is unclear. Here we report that mice fed on an otherwise conventional diet supplemented with vitamin A acetate (VAA) respond to 10(5) semiallogeneic cells (a suboptimal dose) in a host-versus-graft (HvG) reaction, whereas mice on a conventional diet do not. It is possible to transfer this enhanced immune reactivity by injecting lymphoid cells from VAA-fed animals into those syngeneic mice maintained on the conventional diet. Using a positive selection technique, we demonstrate that the phenotype of the cell probably responsible for this phenomenon is Lyt 1+ 2-.     

氯化镧和氯化钆对小鼠免疫细胞作用的体外实验

通过MTT法研究了LaCl3和GdCl3对小鼠免疫细胞的作用.结果表明,GdCl3在0.001～10μmol/L浓度内均能促进小鼠脾细胞的增殖,0.001～0.1μmol/L的LaCl3促进小鼠脾细胞的增殖,其他浓度没有影响;除0.1μmol/L浓度外,其他测试浓度下的LaCl3均促进小鼠T淋巴细胞的增殖;0.001μmol/L的GdCl3抑制小鼠T淋巴细胞的增殖,0.01～1μmol/L时对小鼠T淋巴细胞的增殖没有影响,10μmol/L时转而促进小鼠T淋巴细胞的增殖.浓度为0.1μmol/L的LaCl3和GdCl3对小鼠B淋巴细胞的增殖有抑制作用,其他测试浓度下均促进小鼠B淋巴细胞的增殖.作用时间为4 h时,0.001μmol/L的LaCl3对NK细胞的活性没有影响,其他浓度下的LaCl3均能提高NK细胞的活性,0.001～10μmol/L的GdCl3均能提高NK细胞的活性;作用时间为8 h时,0.001和0.01μmol/L的LaCl3显著降低NK细胞的活性,0.1和1μmol/L的LaCl3提高NK细胞的活性,当浓度为10μmol/L时对NK细胞的活性没有影响,1μmol/L的GdCl3降低NK细胞的活性,其他测试浓度均能提高NK细胞的活性.这提示LaCl3和GdCl3对小鼠免疫细胞的影响模式与其作用浓度、作用时间以及稀土元素的种类都是密切相关的.     

Lymphocytes bearing antigen-specific gamma delta T-cell receptors accumulate in human infectious disease lesions

The majority of T cells bear the T-cell receptor (TCR) alpha beta complex which recognizes foreign antigen peptides only in the context of self major histocompatibility complex (MHC) molecules. Such T cells function in a variety of effector roles and secrete cytokines that mediate the activation and differentiation of other cells in the immune system. Recently, a small subpopulation T cells was found to bear a distinct TCR composed of gamma and delta subunits. In man, TCR gamma delta+ cells are distributed as approximately 5 per cent of the CD3+ cells in all organized lymphoid organs as well as in the skin- and gut-associated lymphoid tissues. Although a limited number of germ-line genes encode the TCR gamma and delta subunits, extensive junctional variation particularly in the delta gene, results in unprecedented diversity for this receptor. The nature of the specificity and immunological functions of these T cells remains enigmatic. We report here that in contrast to the normal low frequency of gamma delta-bearing cells in lymphoid tissues, peripheral blood, or normal skin, the frequency is increased five to eightfold in particular granulomatous reactions of leprosy. TCR gamma delta+ lymphocyte lines from these leprosy skin lesions proliferate in vitro specifically to mycobacterial antigens. This reactivity to foreign antigens appears to require presentation in the context of self-molecules. Moreover, culture supernatants from activated gamma delta T lymphocytes induce adhesion and aggregation of bone-marrow monocytes in the presence of granulocyte monocyte-colony stimulating factor (CSF), suggesting that products of gamma delta-bearing T cells may play a role in the immune response, possibly by stimulating granuloma formation.     

GM-CSF and TNF-alpha cooperate in the generation of dendritic Langerhans cells.

Dendritic cells comprise a system of highly efficient antigen-presenting cells which initiate immune responses such as the sensitization of T cells restricted by major histocompatibility complex molecules, the rejection of organ transplants and the formation of T-cell-dependent antibodies. Dendritic cells are found in many non-lymphoid tissues, such as skin (Langerhans cells) and mucosa, and they migrate after antigen capture through the afferent lymph or the bloodstream to lymphoid organs, where they efficiently present antigen to T cells. Dendritic cells are difficult to isolate and, although they originate from bone marrow their site of maturation and the conditions that direct their growth and differentiation are still poorly characterized. Granulocyte macrophage-colony stimulating factor (GM-CSF) favours the outgrowth of dendritic cells from mouse peripheral blood. Here we extend this finding to man and demonstrate that cooperation between GM-CSF and tumour necrosis factor-alpha (TNF-alpha) is crucial for the generation of human dendritic/Langerhans cells from CD34+ haematopoietic progenitors. The availability of large numbers of these cells should now facilitate the understanding of their role in immunological regulation and disorder.     

Gene rearrangement in cells with natural killer activity and expression of the beta-chain of the T-cell antigen receptor

The mammalian host defence system can be divided broadly into adaptive and non-adaptive immunity. Adaptive immunity is acquired and is mediated by B and T lymphocytes. Non-adaptive immunity is mediated in part by a small subclass of heterogeneous peripheral blood mononuclear cells. This population, termed null cells, consists of haematopoietic precursors and cells mediating natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC). NK cells are a class of non-adherent, non-phagocytic, rapidly cytotoxic lymphocytes which can efficiently lyse a wide variety of tumour cells, virally infected cells and immature cell types of normal origin. Despite the broad range of targets, only a limited number of specificities are thought to be involved in target-cell recognition. Morphologically, NK cells are large granular lymphocytes, but they have been shown to exhibit cell-surface markers characteristic of both T cells and monocytes, raising doubt over their lineage. The recent cloning of the beta-chain of the T-cell antigen receptor has now allowed us to investigate whether some NK cells are T-cell-related. We have examined rearrangement and expression of the beta-chain of the T-cell receptor in cloned murine NK cell lines and fresh murine NK cell populations, and our results support the hypothesis that a subpopulation of NK cells is related to T cells and provide basis for examining whether some NK activity is mediated by a small number of T-cell receptors.     

Thy-1 functions as a signal transduction molecule in T lymphocytes and transfected B lymphocytes

Thy-1, a glycoprotein of relative molecular mass 25,000 (25K), is a major constituent of the cell surface of mouse thymocytes, peripheral T cells and neurones. In man, Thy-1 is present on neurones and on a small percentage of thymocytes, but is absent from peripheral T cells. The amino-acid and complementary DNA sequences of Thy-1 indicate that it has a structure similar to an isolated V (variable region) domain of immunoglobulin. Although the function of Thy-1 is unknown, the ability of different anti-Thy-1 monoclonal antibodies to activate murine T cells or induce functional changes in neuronal cells in vitro suggests that Thy-1 is involved in transmembrane signalling. We now show that crosslinking of murine Thy-1 triggers a rapid rise in the cytoplasmic free calcium concentration ([Ca2+]i), not only in murine T cells and Thy-1.2-transfected human T cells, but also in murine B-lymphoma cells transfected with the murine thy-1.2 gene. These results indicate that the generation and transduction of the signal leading to the rise in [Ca2+]i is independent of the T-cell receptor and other T-cell-specific molecules. The preservation of the [Ca2+]i-modulating function of Thy-1 in various lymphoid cells of two species further suggests that the necessary signal either originates in the Thy-1 molecule itself or is generated in concert with a highly conserved molecules(s) associated with Thy-1.     

Abrogation of resistance to bone marrow transplantation by induction of specific tolerance in natural killer cells?

Hybrid resistance describes the capacity of first generation (F1) hybrids between certain mouse strains to inhibit the growth of tumour or haematopoietic cells of parental origin. The cells that appear to mediate this phenomenon differ from classical T and B lymphocytes in several respects. For example, they are unusually radioresistant, show no immunological memory, are present in thymectomized or congenitally athymic mice, are not functional until about 3 weeks after birth. These characteristics suggest that the effectors are natural killer (NK) cells. Although most of the evidence implicating NK cells in hybrid resistance is circumstantial, the experiments of Warner and Dennert are more direct in that they show that resistance can be restored to mice with a congenital or induced defect in NK activity by the infusion of cells belonging to an NK clone. Conversely, treatment of mice with an antibody to NK cells abrogated hybrid resistance to parental bone marrow grafts. Both NK cells and the effectors of hybrid resistance are generally considered to be nonspecific. We have now investigated this assumption by attempting to prevent hybrid resistance by neonatal tolerance induction with parental strain antigens. Our data indicate that hybrid resistance can be abrogated by this means and that the tolerance is specific and transferable with Thy-1+ spleen cells.