A recombinant antibody with the antigen-specific, major histocompatibility complex-restricted specificity of T cells.

Specific recognition of peptide/major histocompatibility complex (MHC) molecule complexes by the T-cell receptor is a key reaction in the specific immune response. Antibodies against peptide/MHC complexes would therefore be valuable tools in studying MHC function and T-cell recognition and might lead to novel approaches in immunotherapy. However, it has proven difficult to generate antibodies with the specificity of T cells by conventional hybridoma techniques. Here we report that the phage display technology is a feasible alternative to generate antibodies recognizing specific, predetermined peptide/MHC complexes.     

B-lymphoma cells process and present their endogenous immunoglobulin to major histocompatibility complex-restricted T cells

Antigen-presenting B-lymphoma cells were transfected with the gene encoding the immunoglobulin lambda 2 light chain of MOPC315 cells (lambda 2(315). The lambda 2 chain is expressed on the cell surface of the transfectants together with the endogenous heavy chain. The transfectants present an idiotope of the lambda 2(315) light chain to class II-restricted T-cell clones. Recognition by the T cells requires processing of the lambda 2(315) light chain. From these data we conclude that B-lymphoma cells constitutively process and present their immunoglobulins. Secretion and reuptake of the light chain was not necessary for the presentation. Thus, B cells bear two types of idiotypes on their membrane, a native form as surface immunoglobulin and a processed form in the context of products of the major histocompatibility complex.     

Differential expression of non-major histocompatibility complex-restricted cytotoxicity in patients with granular lymphocyte-proliferative disorders associated with or unassociated with severe anemia.

Of 27 patients with granular lymphocyte-proliferative disorders (GLPD), 18 patients had CD3+ T-cell-lineage GLPD (T-GLPD), and 9 patients had CD3-CD16+ natural killer (NK) cell-lineage GLPD (NK-GLPD). In 9 of the 18 patients with T-GLPD, severe anemia of less than or equal to 7.5 g/dl hemoglobin (mean 5.4 g/dl) and erythroid hypoplasia in the bone marrow developed, while the remaining 9 patients with T-GLPD and 9 patients with NK-GLPD exhibited hemoglobin levels of greater than or equal to 10.0 g/dl, and erythroid hypoplasia was not found. The number of leukocytes, neutrophils, lymphocytes or granular lymphocytes in the peripheral blood, or the percentage of lymphocytes in the bone marrow did not differ significantly between the patients with T-GLPD associated with severe anemia and those with T-GLPD not associated with severe anemia, and the immunophenotypes of peripheral blood mononuclear cells (PBMC) were not significantly different either. However, when non-major histocompatibility complex (MHC)-restricted cytotoxicity was assayed with PBMC, T-GLPD patients with severe anemia and NK-GLPD patients exhibited significantly higher levels of non-MHC-restricted cytotoxicity than T-GLPD patients without severe anemia. Because PBMC obtained from T-GLPD patients with severe anemia were shown not to lyse erythroblasts directly, the possibility that patient PBMC lyse erythroblasts in the bone marrow and thus cause anemia seems unlikely. The pathogenesis of anemia in GLPD was discussed.     

Positive selection of major histocompatibility complex-restricted suppressor T cells bearing the predominant idiotype in the immune response to lysozyme.

The lysozyme system provides an excellent model for studying the role of multiple major histocompatibility complex (MHC) genes in the induction and regulation of Ir-gene controlled immune responses. Immunization of H-2b mice leads to concomitant activation of helper and suppressor activities by different epitopes on hen egg-white lysozyme (HEL) and thus phenotype unresponsiveness to native HEL. HEL-specific suppressor T cells in C57BL/10 nonresponder mice show MHC restriction, because their enrichment on antigen-pulsed macrophage monolayers requires syngeneic macrophages as well as HEL. The expression of the selected suppressor function requires interaction between the restricted suppressor precursor cell and an HEL-triggered, suppressor-inducer T cell. The MHC-restricted suppressor precursors bear the predominant idiotype found on anti-HEL antibodies, whereas MHC-restricted helpers do not.     

Positive selection of invariant V alpha 14+ T cells by non-major histocompatibility complex-encoded class I-like molecules expressed on bone marrow-derived cells.

V alpha 14+ T cells are a unique subset expressing an invariant T-cell antigen receptor alpha chain encoded by V alpha 14 and J alpha 281 gene fragments with a 1-nt N region. Most invariant V alpha 14+ T cells develop in extrathymic organs, independent of thymus, and expand at a high frequency in various mouse strains regardless of major histocompatibility complex (MHC) haplotype. In this paper, we show that the positive selection of invariant V alpha 14+ T cells requires a beta 2-microglobulin-associated MHC class I-like molecule not linked to the MHC on chromosome 17. This was determined by linkage analysis on DNA from recombinant mice generated by crossing a C57BL/6 mouse with a wild mouse, Mus musculus molossinus, that is negative for invariant V alpha 14 TCR expression. However, the peptide transporter TAP1 is not necessary for positive selection of invariant V alpha 14+ T cells, indicating the direct recognition of the MHC class I-like molecule without peptide by the invariant V alpha 14 TCR. Further, experiments with bone marrow-chimeric mice show that invariant V alpha 14+ T cells in the periphery are selected by bone marrow cells, suggesting a unique lineage of V alpha 14+ T cells differentiated through a selection process distinct from that of conventional alpha beta TCR+ T cells.     

Thymic depletion and peripheral activation of class I major histocompatibility complex-restricted T cells by soluble peptide in T-cell receptor transgenic mice.

Injection of mice transgenic for a class I major histocompatibility complex-restricted T-cell receptor with a soluble peptide antigen from influenza virus nucleoprotein results in clonal depletion of double-positive immature thymocytes in the thymus and activation of mature T cells in the periphery, accompanied by a transient up-regulation of the T-cell receptor and CD3 and CD8 coreceptor molecules.     

Pathogenic helper T cells

Intractable chronic inflammatory diseases, including autoimmune diseases, autoinflammatory diseases and allergic diseases, are caused by disruption or failure of the immune system. Pathogenic immune cells are presumed to be closely related to the pathogenesis of intractable diseases, but the precise cellular and molecular mechanisms underlying the pathogenesis of these diseases remain unclear. The balance between the T helper type 1 (Th1) and Th2 cell fractions has been believed to be responsible for the differences among inflammatory diseases. However, an analysis of the cells infiltrating inflammatory lesions in mice and humans revealed the generation of pathogenic Th cells with different characteristics at the memory T-cell stage in the peripheral tissues in various inflammatory diseases. In this review, we will summarize and discuss recent progress regarding the characteristics of pathogenic Th cells, their mode of action, and the molecular mechanisms that regulate the pathology of intractable chronic inflammatory diseases, particularly those with tissue fibrosis. We hope this article will help clarify the pathogenesis of these diseases and propose a future direction for research.     

Allo-major histocompatibility complex-restricted cytotoxic T lymphocytes engraft in bone marrow transplant recipients without causing graft-versus-host disease.

Previous experiments in humans and mice have shown that allogeneic donors can serve as a source of cytotoxic T lymphocytes (CTL) specific for proteins, such as cyclin-D1 and mdm-2, expressed at elevated levels in tumor cells. In vitro, allo-major histocompatibility complex (MHC)-restricted CTL against these proteins selectively killed allogeneic tumor cells, including lymphoma, but not normal control cells. This suggested that these CTL may be useful for adoptive tumor immunotherapy, provided that they (1) survive in MHC-disparate hosts, (2) maintain their killing specificity, and (3) do not attack normal host tissues. Here, we used cloned allo-restricted CTL isolated from BALB/c mice (H-2(d)) that killed H-2(b)-derived tumor cells expressing elevated levels of the mdm-2 target protein. When these CTL were injected into bone marrow transplanted (BMT) C57BL/6 (H-2(b)) recipients, they consistently engrafted and were detectable in lymphoid tissues and in the bone marrow (BM). Long-term survival was most efficient in spleen and lymph nodes, where CTL were found up to 14 weeks after injection. The administration of CTL did not cause graft-versus-host disease (GVHD) normally associated with injection of allogeneic T cells. These data show that allo-restricted CTL clones are promising reagents for antigen-specific immunotherapy in BMT hosts, because they engraft and retain their specific killing activity without causing GVHD.     

Neonatal tolerance to alloantigens alters major histocompatibility complex-restricted response patterns.

Male-specific transplantation antigen (H-Y)-immune cytotoxic T cells of some individual CBA/H mice exhibit lytic activity on male and female allogeneic targets (e.g., H-2b). Neonatal tolerance to H-2b abrogates the ability of CBA mice to generate secondary H-Y-immune cytotoxic T cells, but such cell activity to third-party alloantigens and to Bebaru and influenza virus is not impaired. The results are discussed in relationship to dominant major histocompatibility complex-coded immune response gene effects on cytotoxic T-cell responses.     

CD4+ T cells appear capable of initiating graft-versus-host disease across non-major histocompatibility complex (MHC) barriers in man

Twelve patients with haematological malignancy received cyclophosphamide 120 mg/kg, fractionated total body irradiation 12 Gy, oral cyclosporin and an HLA-identical sibling marrow transplant depleted of T cells by incubation with monoclonal antibodies directed against the CD2 and CD8 antigens and rabbit complement. The phenotype of the residual T cells in the donor marrow inocula was CD3+, CD4+, CD8-. To exclude the possibility that this represented modulation or blocking of the CD8 antigen, T-depleted and non-depleted marrow aliquots from these donors were bulk-cultured for 10 days with phytohaemagglutinin and interleukin-2. Even after this attempted expansion, only a small proportion of cultured T cells from the depleted aliquots (in contrast to the non-depleted aliquots) expressed the CD8 antigen. Since all patients receiving CD3+, CD4+, CD8- marrow developed mild or moderate acute graft-versus-host disease (GVHD), we conclude that CD4+ T cells are capable of initiating acute GVHD across non-MHC barriers in man.     

Th1/Th2细胞失衡在不稳定型心绞痛发病机制中的作用

目的:通过与超敏C反应蛋白(hsCRP)检测对比,探讨Th1相关的白细胞介素(IL)-12、IL-18和Th2相关的IL-10与不稳定型心绞痛的关系。方法:临床及冠状动脉造影确诊的50例不稳定型心绞痛患者作为病例组(男40例,女10例),30例非冠心病者作为对照组(男23例,女7例)。采用ELISA法检测血清中IL-10,IL-12及IL-18水平,乳胶增强免疫比浊法检测血清hsCRP水平。结果:病例组中,IL-12,IL-18水平增高,IL-10水平降低,均差异有统计学意义。对照组中上述指标没有显著改变。病例组中,hsCRP水平与IL-12,IL-18水平呈正相关,而与IL-10水平呈负相关。IL-12与IL-18水平呈正相关而两者均与IL-10水平呈负相关。结论:在不稳定型心绞痛患者的炎性反应中,Th2细胞活性降低,Th1细胞活性升高,导致了Th1/Th2的失衡。     

Differentiation-dependent sensitivity of human B-cell-derived lines to major histocompatibility complex-restricted T-cell cytotoxicity.

Sets of Burkitt lymphoma lines and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) derived from the same individuals were compared for sensitivity to cytotoxic T-lymphocyte (CTL) clones. Major histocompatibility complex class I antigen-restricted CTL clones were generated by stimulating the lymphocytes of an EBV-seropositive individual with the autologous LCL. One clone (BK-20) lysed the autologous and allogeneic HLA-A11-expressing LCLs but not mitogen-induced B lymphoblasts. Thus the clone was selectively cytotoxic for LCLs. Allospecific CTL clones directed against the HLA-A11 antigen were generated from an EBV-seronegative individual. One clone (WP-36) was selectively cytotoxic for the appropriate allospecific LCL, whereas another clone (WP-21) lysed also T and B lymphoblasts. None of the four Burkitt lymphoma lines established in parallel with the CTL-sensitive LCLs were lysed. Two of the Burkitt lymphoma lines were EBV-negative, and EBV-positive sublines were derived from these by in vitro infection. One but not the other of the two convertants became sensitive to all three types of CTL clones. The CTL-sensitive converted line had also acquired some LCL characteristics: increased cell size, aggregation, and a shift in several of the B-cell-specific surface markers. The CTL-resistant convertant expressed EBV antigens but showed no phenotypic change. These findings suggest that the cellular phenotype plays a decisive role in the sensitivity of B-cell-derived lines to the lytic effect of LCL-selective autologous and allogeneic CTLs.     

Molecular dynamics in the membranes of helper T cells.

We provide evidence that redistributions and interactions of integral proteins in the fluid membranes of helper T (Th) cells may play important roles in Th-cell activation. A particular monoclonal antibody, 3D3, directed to a clonotypic determinant on the T-cell receptor (TCR) of the cloned Th-cell line D10, had previously been shown to be distinctively capable of directly activating D10 cells at low concentrations. We demonstrate here by immunofluorescence experiments that it is also distinctively able itself to produce a clustering (capping) of the TCRs on the D10 cell surface. Simultaneously, by means of double-immunofluorescence experiments, we find that the 3D3-induced clustering of the TCRs distinctively produces a co-clustering of the accessory molecule CD4 with the TCR clusters, although the CD4 and TCR molecules are normally independent of one another in the D10 cell membrane. These results, and related ones previously obtained from studies of the interactions of D10 Th cells with antigen-presenting cells, are analyzed to suggest that the membrane clustering of TCRs and the induced TCR-CD4 interactions are critical to the signaling events in Th-cell activation.     

Class I major histocompatibility complex-restricted cytolytic T lymphocytes recognize a limited number of sites on the influenza hemagglutinin

Two distinct regions of the influenza A/JAP/305/57 hemagglutinin molecule are identifiable as sites recognized by murine class I major histocompatibility complex (MHC) (H-2d)-restricted cytolytic T lymphocytes (CTL) generated in response to immunization with infectious type A influenza virus. Each of these sites can be mimicked by a synthetic oligopeptide of approximately 20 amino acids. Data presented herein indicate that these two sites define the dominant immunogenic epitopes on the hemagglutinin recognized by H-2Kd-restricted CTL. These same sites are not efficiently recognized by hemagglutinin-specific class I MHC-restricted CTL of several unrelated MHC haplotypes. These observations show that even for a large complex glycoprotein molecule like the influenza hemagglutinin, only a limited number of class I CTL recognition sites are generated in the infected cell and that the subset of immunogenic epitopes is dependent on the MHC haplotype of the responding individual. These parameters need to be considered in the design of synthetic and recombinant vaccines.     

The specific direct interaction of helper T cells and antigen-presenting B cells.

Cell couples have been formed by mixing an antigen- and Ia-specific cloned helper T-cell line with a B-cell hybridoma presenting the antigen. By immunofluorescence observations, we have shown that the microtubule-organizing center (MTOC) inside the helper T cell, but not in the bound antigen-presenting cell, becomes oriented to face the area of specific cell-cell contact. This MTOC orientation is antigen- and Ia-specific, and thus provides direct evidence for the specific interaction of a helper T cell with a B cell. It is presumed that the function served by this MTOC orientation, which is accompanied by the coordinate reorientation of the Golgi apparatus, is to target Golgi apparatus-derived secretory vesicles, containing putative lymphokines and/or growth factors, from the helper T cell directly to the antigen-presenting cell.     

滤泡辅助T淋巴细胞与HIV感染

滤泡辅助T淋巴细胞(T follicular helper cells,Tfh)是宿主正常体液免疫应答中的重要组成部分,为抗原特异性B细胞提供了关键的辅助作用。近年的研究发现,HIV感染可导致Tfh细胞的数量和功能异常,并可能与慢性HIV感染中体液免疫的异常、中和性抗体的产生及疫苗的免疫效果相关。本文对近年来有关Tfh细胞的研究进展进行综述,以期更好地理解HIV感染的致病机制。     

Clustering of non-major histocompatibility complex susceptibility candidate loci in human autoimmune diseases

Human autoimmune diseases are thought to develop through a complex combination of genetic and environmental factors. Genome-wide linkage searches of autoimmune and inflammatory/immune disorders have identified a large number of non-major histocompatibility complex loci that collectively contribute to disease susceptibility. A comparison was made of the linkage results from 23 published autoimmune or immune-mediated disease genome-wide scans. Human diseases included multiple sclerosis, Crohn’s disease, familial psoriasis, asthma, and type-I diabetes (IDDM). Experimental animal disease studies included murine experimental autoimmune encephalomyelitis, rat inflammatory arthritis, rat and murine IDDM, histamine sensitization, immunity to exogenous antigens, and murine lupus (systemic lupus erythematosus; SLE). A majority (≈65%) of the human positive linkages map nonrandomly into 18 distinct clusters. Overlapping of susceptibility loci occurs between different human immune diseases and by comparing conserved regions with experimental autoimmune/immune disease models. This nonrandom clustering supports a hypothesis that, in some cases, clinically distinct autoimmune diseases may be controlled by a common set of susceptibility genes.     

Autocrine growth inhibition of a cloned line of helper T cells.

The growth of T lymphocytes is dependent on the T-cell growth factor interleukin 2 (IL-2), which causes T cells bearing high-affinity receptors for IL-2 to proliferate. Most cloned helper-T-cell lines can be shown to both produce and respond to IL-2; thus, growth of such cells is by an autocrine mechanism. We report that the failure of the cloned murine T-cell line D10.G4.1 to respond to its own IL-2 results from the secretion, by the same cells, of a potent inhibitor of the IL-2-driven T-cell proliferative response. This inhibition can be overcome by increasing the number of IL-2 receptors expressed by the target cell. In the cloned T-cell line producing the inhibitory substance, this increase in IL-2 receptors is driven by the monokine interleukin-1. We propose that this inhibitor of IL-2 responses may play a role in preventing "bystander" activation of T cells by IL-2 released in vivo and could be a potent pharmacologic agent.