An experimental model for canine visceral leishmaniasis

Seven mixed-breed dogs were challenged with either promastigotes or amastigotes of Leishmania donovani infantum strains recently isolated from naturally infected dogs. Different routes and numbers of parasites were utilized and each dog was monitored for at least 1 year post-infection. Anti-parasite specific antibody levels were measured by enzyme-linked immunosorbence, immunofluorescence, crossed-immune electrophoresis and Western blotting on crude antigen. Western blotting on two pure parasite proteins, dp72 and gp70-2, was also done. Mitogenic and antigen-specific stimulation of peripheral blood lymphocytes was monitored; and the haematological, clinical and parasitological parameters measured. Dogs challenged with amastigotes exhibited a more pronounced humoral response to leishmanial antigens. Only in one case was strong antigen-specific proliferation detected. Clinical signs of disease, including hypergammaglobulinaemia, enlarged lymph nodes and the presence of parasites, were also more apparent in the dogs challenged with amastigotes. None of the seven dogs died. Serum antibodies to leishmanial antigens were apparent between 1.5 to 3 months following challenge and correlated with the appearance of enlarged lymph nodes, hypergammaglobulinaemia and the presence of parasites in tissue biopsies. Serum antibodies remained chronically high in these dogs throughout the period of the study. Only one dog (1/3) challenged intravenously with promastigotes and the dog challenged intradermally with amastigotes produced transient antibody responses to leishmanial antigen.     

小儿白血病瘤细胞P—糖蛋白测定方法及应用

本文介绍免疫组化法检测小儿白血病瘤细胞（Ｐ－ｇｐ）。检测３０例小儿白血病细胞膜Ｐ－ｇｐ，观察其原发耐药性。３０例中有８例ｐ－ｇｐ阳性，总阳性率２６．６７％，其中ＡＮＬＬ单项阳性率３３．３３％，ＡＬＬ为２０％。本组病例耐约性最高的是ＣＭＬ，其次是ＡＮＬＬ，ＡＬＬ组最低。同时发现ＭＤＲ阳性者复发率高，ＭＤＲ阴性者复发率低，多因素分析表明ＭＤＥＲ对初诊白血病患者预后及抗癌药物选择有重要意义。目的临床评价ＭＤＲ采用检测ｍｄｒ１ｍＲＮＡ或Ｆ－ｇｐ，本文认为采用简便、快速的免疫组化法检测Ｐ－ｇｐ在临床上具有较大的实用价值。     

Inhibition of HIV-1 by modification of a host membrane protease

While it is clear that CD4 Is the receptor for the gp120 envelopeprotein of HIV-1, substantial evidence suggests that other hostcell proteins are required for successful membrane fusion. Studieswere initiated to examine the potential for a protein receptorwhich has an elastase-like character to participate in fusionof HIV-1 with permissive host cells. A synthetic elastase inhibitorwas shown to significantly reduce HIV-1 infectivity when presentduring, but not after, the initial contact between virus andcells. A human T cell elastase-like membrane component was purifiedand shown to be lipid-associated. By competitive Inhibition,the purified protein was shown to bind gp160 within the HIV-1fusion domain. The binding parameters of whole T cell membraneextract, with a hydrophobic pentapeptide representative of thefusion domain, suggested an elastase-like protein is the single,secondary T cell receptor for HIV-1 (K = 1x10³ M^–1). Thepentapeptide interacted with porcine and human (epithelial andpolymorphonuclear leukocyte), but not murine, elastase isoforms,suggesting its participation In the permissiveness of host cellsto infection.     

ATL and HTLV-I:In vivo cell growth of ATL cells

The mechanism of leukemogenesis or neoplastic cell growth in adult T cell leukemia (ATL) still remains unclear, although Tax of human T cell leukemia/lymphoma virus type I (HTLV-I), the etiologic virus, has been reported to affect the expression of various cellular genes which encode molecules involved in cell growth or cell death. We have studied the cell growth of HTLV-I-infected human T cells in severe combined immunodeficiency (SCID) mice and found that fresh leukemic cells or cell lines derived from leukemic cell clones but not HTLV-I-infected cell lines of nonleukemic cell origin showed tumorigenicity, and neither HTLV-I nor IL-2 expression was needed for cell growthin vivo, indicating that accumulating changes in addition to the initial events induced by HTLV-I infection were required for the development of ATL. The interaction between ATL cells and vascular endothelial cells appears to be one of the important factors which determine the pattern of organ infiltration by leukemic cells. E-selectin and its ligand are one of the major cell adhesion pathways between ATL cells and human umbilical vein endothelial cells (HUVEC). Another pathway that had not been identified was studied using newly developed monoclonal antibodies capable of blocking cell adhesion. The molecules which directly mediate adhesion between ATL cells and HUVEC were determined to be OX40 and gp34, a member of the tumor necrosis factor receptor (TNF-R) family and TNF family, respectively. The OX40/gp34 system may play a key role in the trafficking and homing of not only ATL cells but also activated normal T cells.     

Identification of a novel gp100/pMel17 peptide presented by HLA-A*6801 and recognized on human melanoma by cytolytic T cell clones

Melanoma-associated peptides recognized by cytolytic T lymphocytes (CTL) in the context of several histocompatibility leukocyte antigens (HLA) are required for the development of specific immunotherapies. Using a transient transfection assay into COS-7 cells, we identified the gp100/pMel17 melanosomal protein as the shared antigen recognized by three independent CD8+ CTL clones in HLA-A*6801-restricted fashion. This finding was confirmed by the correlation between lack of gp100/pMel17 protein in a number of HLA-A*6801-positive melanomas and their resistance to lysis/cytokine production by the specific effectors. The gp100/pMel17 antigenic epitope was identified based on recognition of subfragments and on a computer-based prediction algorithm. Among a panel of gp100/pMel17-derived synthetic peptides only the 10-mer HTMEVTVYHR (gp100/pMel17182-191) induced tumor necrosis factor (TNF) release by CTL clones when pulsed on suitable target cells whereas both the 10-mer and the shorter 9-mer gp100/pMel17183-191 sensitized the same antigen-pulsed cells to lysis. In conclusion, the identification of the HTMEVTVYHR peptide will extend to HLA-A*6801 melanoma patients the possibility to exploit gp100/pMel17 melanosomal protein for experimental and clinical studies.     

gp49B1 suppresses stem cell factor-induced mast cell activation-secretion and attendant inflammation in vivo

We report that gp49B1, a mast cell membrane receptor with two immunoreceptor tyrosine-based inhibitory motifs (ITIM), constitutively inhibits mast cell activation-secretion induced by stem cell factor (SCF), a tissue-derived cytokine that also regulates mast cell development. The intradermal injection of SCF into the ears of gp49B1 null (gp49B(-/-)) mice elicited approximately 4- and 2.5-fold more degranulating mast cells and tissue swelling caused by edema, respectively, than in gp49B(+/+) mice. SCF did not induce tissue swelling in mast cell-deficient mice, and the responsiveness of gp49B(-/-) mice to mast cell-associated amine and lipid mediators was unaltered. When gp49B(+/+) and gp49B(-/-) mice were pretreated with antagonists of the amines, SCF-induced tissue swelling was reduced by >90% and 60%, respectively, and it was reduced by >90% in both genotypes when a cysteinyl leukotriene receptor antagonist was also provided. Hence, the dominant contribution of secretory granule amines to SCF-induced tissue swelling is the result of gp49B1-mediated inhibition of the production of cysteinyl leukotrienes by mast cells. Our findings also provide the first example of an ITIM-bearing receptor that constitutively suppresses inflammation generated in vivo independently of the adaptive immune response by a receptor that signals through intrinsic tyrosine kinase activity rather than immunoreceptor tyrosine-based activation motifs.     

Requirement of the T cell receptor for antigen presentation by T lymphocytes. Effect of envelope glycoproteins of HIV-1 on antigen presentation by T cells.

We have developed CD4+, tetanus antigen-specific T cell clones that proliferate in the presence of tetanus antigen and autologous irradiated peripheral blood leucocytes (PBL) as antigen-presenting cells (APC). There have been several reports that T cells can present antigen themselves. We have used tetanus antigen-specific T cell clones to examine the effects of envelope glycoproteins of HIV-1 on processing and presentation of antigen to T cells. Cloned T cells were pre-incubated with soluble crude preparation of tetanus antigen for 4 h at 37 degrees C, irradiated, and used as APC (T-APC). These cells could present antigen, as assessed by the ability of the autologous cloned T cells to proliferate. Resting T cells and phytohaemagglutinin-activated T cell blasts from autologous PBL could not present tetanus antigen to the responder cloned T cells. Antigen presentation by T-APC was abrogated by treating cells with anti-HLA-DR but not by anti-HLA-DQ monoclonal antibodies; treatment of tetanus antigen-pulsed T-APC with anti-tetanus antibody also blocked the ability of these cells to induce proliferation in responder T cells. Antigen presentation by cloned T cells was by a chloroquine-resistant pathway. Pretreatment of T-APC with envelope glycoprotein of HIV-1, gp120, did not affect the proliferative responses of the responder T cells. These data suggest that gp120 does not inhibit the antigen-presenting function while suppressing antigen-specific responses.     

中国92例HIV/AIDS患者HIV-1 gp41 2F5和4E10中和抗体表位变异研究

目的 探讨92例HIV/AIDS患者HIV-1病毒近膜端(membrane proximal external re-gion,MPER)中和抗体2F5和4E10保守表位ELDKWA、NWFDIT氨基酸变异特点,为中国HIV/AIDS患者免疫治疗以及疫苗设计提供数据.方法 Nest-PCR扩增HIV-1 env区gp41段基因,核酸序列测定,翻译为氨基酸与HIV-1 Sequence Database HXB Ⅱ参考株中和抗体表位数据比对,分析2F5、4E10中和表位氨基酸变异情况.结果 92例HIV/AIDS患者HIV-1外膜蛋白env gp41段中和抗体2F5、4E10保守表位氨基酸均存在突变;2F5中和抗体表位主要有E662A(14.1%)、K665S(17.4%)、A667K(16.3%)突变;4E10中和抗体表位主要有N671S(13.0%)、D674S(3.3%)、T676S(16.3%)突变;CRF_B'C亚型与B'亚型的2F5和4E10表位氨基酸突变差异具有统计学意义(P<0-05);CRF_B'C与CRF01_AE亚型2F5表位突变差异具有统计学意义(P<0.05);B'亚型缓慢进展者、HIV感染者和AIDS患者的4E10表位氨基酸突变差异具有统计学意义(P<0.05).结论 92例HIV/AIDS患者HIV.1包膜蛋白env gp41段中和抗体2F5、4E10中和表位氨基酸存在突变,且变异多样化;不同亚型中和抗体保守表位氨基酸位点变异有差异;B'亚型4E10中和抗体表位变异可能与疾病进展有一定联系.     

gp130胞外区近膜端缺失的突变体介导IL-6信号的研究

目的研究ｇｐ１３０胞外区远膜端和近膜端在ＩＬ－６信号转导中的作用。方法用分子克隆手段构建全长的膜结合型ｇｐ１３０分子和胞外区第３０１～５８２位氨基酸残基缺失的突变体分子，并通过阻滞电泳方法比较突变体与野生型分子在传导信号方面的差异。结果通过酶切鉴定、序列分析和表达检测，证明野生型和突变体ｃＤＮＡ表达载体构建正确，并有效表达；阻滞电泳结果表明，在ＳＫＯ－００７细胞和Ｍｏｌｔ－４细胞中，突变体分子与野生型ｇｐ１３０都能介导ＩＬ－６信号。结论ｇｐ１３０分子胞外区远膜端在ＩＬ－６信号转导中发挥重要作用；而近膜端并非ＩＬ－６信号转导所必需。     

Priming B cell-mediated anti-HIV envelope responses by vaccination allows for the long-term control of infection in macaques exposed to a R5-tropic SHIV

The potential of vaccine-elicited anti-HIV envelope antibodies to control HIV-infection was evaluated by immunizing macaques with the HIV envelope protein and transiently depleting them of their CD8+ cells before intravenous challenge with the pathogenic CCR5-tropic SIV/HIV chimeric virus, SHIV(SF162P4). Although sterilizing immunity was not achieved, all vaccinated animals effectively controlled infection and remained free of disease for the duration of observation (over 3 years). In contrast, during the same period, the control animals progressed to disease. Both the vaccinees and the controls developed robust cell-mediated antiviral and neutralizing antibody responses following infection. A comparative analysis of these responses suggests that the more effective long-term control of infection by the vaccinated animals is due to the more rapid development of anti-HIV envelope antibodies. These studies suggest that priming by vaccination of B cell anti-HIV envelope responses maybe crucial for the long-term control of HIV infection.