The relative contribution of antibody production and CD8+ T cell function to immune control of Trypanosoma cruzi

The life cycle of the protozoan parasite Trypanosoma cruzi in mammalian hosts includes both non-dividing trypomastigote forms which circulate in the blood and replicating intracellular amastigotes which reside within the cytoplasm of a variety of host cells. In this study we have used mice with induced mutations in genes responsible for either antibody production or cytolytic T lymphocyte (CTL) function to examine the relative contributions of these effector mechanisms to control of T. cruzi. Mice deficient in the production of antibodies exhibited a delay in the rise in acute phase parasitaemia and an extended time to death relative to mice lacking CD8⁺ T cells. Nevertheless, B cell deficient mice eventually succumbed to the infection. Prior infection with an avirulent strain of T. cruzi failed to protect either CD8⁺ T cell-deficient mice or B cell deficient mice from challenge infection with virulent parasites. In contrast, mice with disruptions in the genes controlling perforin- or granzyme B-mediated cytolytic pathways had parasitaemia and mortality rates similar to wild-type mice and were protected from secondary infection by prior exposure to avirulent parasites. These results 1) confirm that antibody production, although secondary in importance to cellular responses, is nevertheless absolutely required and 2) perforin- or granzyme B-mediated lytic pathways are not required for control of T. cruzi infection.     

慢性活动性乙型肝炎CD_4/CD_8比值与体液免疫关系的探讨

采用IFA法检测了32例慢性活动性乙型肝炎外周血T细胞亚群CD_4/CD_8比值和免疫球蛋白IgG、IgA。结果表明,CD_4明显降低,CD_8明显升高,CD_4/CD_8比值显著下降;IgG、IgA明显升高;并发现CD_4/CD_8比值与IgG(γ=-0.485,P<0.01)及IgA(γ=-0.308,P<0.05)呈直线负相关;对其中6例患者进行了动态观察,结果提示,慢性活动性乙型肝炎的细胞免疫功能紊乱导致体液免疫功能异常亢进。     

Signaling of programmed cell death induction in WEHI-231 B lymphoma cells

The murine WEHI-231 B lymphoma is highly sensitive to membrane immunoglobulin ligation which leads to programmed cell death (PCD) in this cell line. To study the molecular pathways involved in PCD induction in these cells, we derived two variants of WEHI-231 resistant to anti-Ig treatment. The level of bcl-2 mRNA was identical in the wild type and the variants, either untreated or anti-Ig treated, suggesting that PCD is not under the control of bcl-2 in WEHI-231 cells. In contrast, c-myc gene expression was markedly different in the wild type and the variants, both in the unstimulated and anti-Ig-stimulated state. Our findings are interpreted in the context of the dual capacity of c-myc to promote cell growth or cell death, in conjunction with other growth regulatory signals.     

Memory T Cells in Transplantation: Generation, Function, and Potential Role in Rejection

The adaptive immune system is endowed with long‐lived memory to recall previous antigen encounters and respond more effectively to them. Memory immune responses are mediated by antigen‐specific memory T lymphocytes that exhibit enhanced function compared with naïve T cells that have never encountered antigen. While the generation of memory T cells specific for pathogens is beneficial in providing protective immunity, memory T cells specific for alloantigens can be deleterious to the recipient of a transplanted organ. In graft rejection, memory T cells mediate accelerated, ‘second‐set’ rejection and their presence has been associated with increased propensity for early rejection. Recent findings have demonstrated that alloreactive memory T cells can be generated via exposure to alloantigens, as well as stimuli that are cross‐reactive with alloantigens, and are therefore likely present in ‘naïve’ individuals. This review focuses on the characteristics of memory T cells which make them of special interest to the transplant community, including differential activation requirements, broad homing properties, and resistance to tolerance induction. The multiple ways in which memory T cells can contribute to early and late graft rejection are discussed, as well as potential targets for combating alloreactive memory to be considered in the future design of tolerance induction strategies.     

多表位组合肽诱导HLA-A2+人PBMC产生抗原特异性CD8+ T细胞应答的研究

目的 探讨基于HBV抗原优势表位的治疗性多肽抗原组分、结构与体外诱导CD8^ T细胞应答之间的关系。方法 用计算机辅助分子设计技术，设计基于HBV抗原免疫优势性CTL表位、B细胞表位和破伤风类毒素通用Th细胞表位的3种治疗性多肽候选疫苗分子，经Merrifield固相多肽合成技术合成，并经HPLC纯化、鉴定。以HLA-A2^ 健康人和慢性乙型肝炎患者的PBMC为实验对象，进行体外诱导CD8^ T细胞应答的免疫学功能研究。结果所设计治疗性多肽分子可在体外诱导较强的抗原特异性CD8^ CTL应答；“-AAA-”铰链区设计和“Th B”细胞表位的引入可增强CTL表位肽的免疫原性。结论 提示在治疗性表位多肽疫苗的分子设计中，短而高柔性的“铰链区”设计和“Th B”细胞表位的引入可显著提高小分子表位肽的免疫原性。     

HLA-G与移植免疫

非经典HLA Ⅰ类分子(HLA-Ⅰb)HLA-G参与抗原递呈,通过相应受体调节NK细胞及T淋巴细胞功能,是一个 重要的免疫调节分子。HLA-G分子的免疫调节作用已从母胎免疫耐受扩展到肿瘤免疫、抗感染免疫和器官移植免疫等领域, 近年来在移植免疫方面取得了重要进展。     

重组hCTLA4Ig对小鼠脾淋巴细胞活化的抑制作用

目的 探讨基因重组hCTLA4Ig对小鼠脾淋巴细胞增殖反应的影响。方法 于不同时相点在Con A刺激的小鼠脾淋巴细胞及BALB/c与昆明种小鼠混合淋巴细胞培养中加入不同剂量hCTLA4Ig，应用^3H-TdR掺入法测定淋巴细胞增殖情况。结果 重组hCTLA4Ig能显著抑制ConA刺激的脾淋巴细胞及混合淋巴细胞反应中的细胞增殖。结论 重组hCTLA4Ig能抑制鼠淋巴细胞的活化。     

Selective Depletion of the Allo-Antigen Specific T Cells by Fas/FasL Pathway by Cytokine IFN-γ and IL-2

Severegraft versus hostdisease (GVHD)isthemajorcauseoffailureofallogeneichematopoieticstemcelltransplantation (allo HSCT) .Thedonormatu rateTlymphocytesareactivatedwhentheyrecognizeallo histocompatibilityantigenofrecipients ,anddi rectlyswitchongraft versus hostreactionandcausetargettissueinjury[1] .DepletionofTcellsingraftorinhibitionoftheirfunctioncoulddeceleratetheoccur renceanddevelopmentofGVHD[2 ] .However ,Tcellsareabletoresistinfection ,killtumorcellsandsecretecytokinessuchasIL 3…     

Distribution of the cytogenetic abnormality +i(3)(q10) in persistent polyclonal B-cell lymphocytosis: a FICTION study in three cases

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare entity characterized by a moderate but sustained lymphocytosis where some binucleated or bilobulated circulating forms constitute, even if they are not entirely specific, the cytological hallmark of the disease. An additional chromosome long arm i(3)(q10) has recently been reported as a recurrent cytogenetic aberration, contrasting with a usual polyclonal immunoglobulin expression. To determine more precisely the distribution of the chromosomal abnormality within the peripheral lymphocyte population and study the relationship between the +i(3)(q10) and the bilobulated character, we investigated three new cases of PPBL displaying the cytogenetic abnormality on the karyotype, using a technique of simultaneous fluorescence immunophenotyping and interphase cytogenetics (FICTION). We demonstrated that the +i(3)(q10) was restricted to the B lymphocytes, independently of the κ or λ light chain isotype and was present in both bilobulated and non-bilobulated cells. Therefore it is likely that the cytogenetic abnormality occurs at an early stage of lymphocyte differentiation in a precursor cell already committed to the B-cell lineage, before any rearrangement of immunoglobulin genes has taken place.     

胃癌手术前后活化CD69、HLA-DR的变化与临床意义

目的了解胃癌患者围手术期的免疫功能变化,探讨其临床意义.方法应用流式细胞仪检测42例胃癌患者手术前后外周血中T细胞2种表面抗原CD69、HLA-DR,并与良性病变患者进行对照.结果发现胃癌患者术前CD69细胞百分率低于对照组(P＜0.01),HLA-DR细胞百分率与对照组相近(P＞0.05).术后胃癌患者的CD69、HLA-DR细胞百分率较术前均明显增高(P＜0.01).结论胃癌患者术前免疫功能低下,术后活化T细胞明显增多,表明切除肿瘤有利于提高患者的免疫功能,增强机体的抗癌能力,故应尽量争取根治性切除肿瘤.