The T cell antigen receptor complex expressed on normal peripheral blood CD4-, CD8- T lymphocytes. A CD3-associated disulfide-linked gamma chain heterodimer

IL-2-dependent cell lines were established from normal peripheral blood T lymphocytes that express neither CD4 nor CD8 differentiation antigens. CD3+,4-,8- cell lines from 15 different donors failed to react with WT31, an mAb directed against the T cell antigen receptor alpha/beta heterodimer. Anti-Leu-4 mAb was used to isolate the CD3/T cell antigen receptor complex from 125I-labeled CD3+,4-,8- (WT31-) T cells. Using detergent conditions that preserved the CD3/T cell antigen receptor complex, an approximately 90 kD disulfide-linked heterodimer, composed of approximately 45- and approximately 40- (or approximately 37-) kD subunits, was coimmunoprecipitated with the invariant 20-29-kD CD3 complex. Analysis of these components by nonequilibrium pH gradient electrophoresis indicated that the approximately 40-kD and approximately 37-kD subunits were similar, and quite distinct from the more basic approximately 45-kD subunit. None of these three subunits reacted with an antibody directed against a beta chain framework epitope. Heteroantiserum against a T cell receptor gamma chain peptide specifically reacted with both the approximately 37- and approximately 40-kD CD3-associated proteins, but not with the approximately 45-kD subunit. CD3+,4-,8- cells failed to transcribe substantial amounts of functional 1.3-kb beta or 1.6-kb alpha mRNA, but produced abundant 1.6-kb gamma mRNA. Southern blot analysis revealed that these CD3+,4-,8- cell lines rearranged both gamma and beta genes, and indicated that the populations were polyclonal. The expression of a CD3-associated disulfide-linked heterodimer on CD3+,4-,8- T cell lines established from normal, adult peripheral blood contrasts with prior reports describing a CD3-associated non-disulfide-linked heterodimer on CD3+/WT31- cell lines established from thymus and peripheral blood obtained from patients with immunodeficiency diseases. We propose that this discrepancy may be explained by preferential usage of the two C gamma genes in T lymphocytes.     

Functional properties of a unique subset of cytotoxic CD3+ T lymphocytes that express Fc receptors for IgG (CD16/Leu-11 antigen)

A subset of peripheral blood T lymphocytes coexpressing CD3 and IgG Fc receptors (FcR) (CD16/Leu-11 antigen) have been identified, isolated, and functionally characterized. The CD3+, CD16+ cells were established in short-term culture using growth medium containing interleukin 2 (IL- 2). Both the freshly isolated cells and the cultured cell line stably expressed the CD3+, CD16+ phenotype. Furthermore, a majority of these T cells lacked either CD4 or CD8 expression. Like in vitro-activated cytotoxic T lymphocytes and natural killer (NK) cells, the CD3+, CD16+ cells showed numerous azurophilic granules. Although these cells failed to mediate significant levels of NK cell-mediated cytotoxicity even after stimulation with IL-2, they efficiently functioned as effectors of antibody-dependent cellular cytotoxicity (ADCC). The Ig isotype specificity of the ADCC was analyzed using an isotype switch-variant family of a murine anti-HLA monoclonal antibody (mAb). Similar to the CD3-, CD16+ NK cell population, the CD3+, CD16+ T cells preferentially used the IgG2a antibody to mediate ADCC. The CD3+, CD16+ cells demonstrated a proliferative response when cocultured with either a NK- sensitive tumor cell line, K562, or a NK-insensitive B lymphoblastoid cell line, CCRF-SB. The response against CCRF-SB was significantly inhibited by anti-IL-2 receptor antibody, whereas the response against K562 was only partially diminished. Cytotoxicity was also induced in the CD3+, CD16+ population by the presence of anti-CD3 mAb, indicating that cytotoxicity can be triggered by stimulation via the CD3-T cell antigen receptor complex. By isolating these CD3+, CD16+ cells from the peripheral blood of a normal, healthy individual, it has been possible to extensively study the morphology, antigenic phenotype, and functional behavior of this unique subset of T lymphocytes expressing IgG FcR.     

多发性硬化患者外周血CD8+CD28-调节性T细胞的变化

目的 探讨多发性硬化(MS)患者外周血CD8+CD28-T细胞数量的变化及临床意义.方法 采用前瞻性病例对照研究,收集自2005年10月至2008年8月间在温州医学院附属第一医院神经专科病门诊或病房治疗的处于急性活动期的复发缓解型MS患者51例,均符合2005年修改的Mc-Donald诊断标准[2].所有住院患者均给予甲基强的松龙1.0 g/d,连续使用5 d后改为强的松60mg/d,12 d后减量,总疗程不超过6周,对14例MS患者进行治疗前后的动态观察.以20例健康体检者为对照组(NC组),MS组和NC组在年龄、性别构成上差异无统计学意义.采用流式细胞技术检测外周血CD8+CD28-,CD8+CD28+,CD8+及CD4+CD8-T细胞的百分比.两组间均数比较采用独立样本t检验,治疗前后比较采用配对样本t检验,相关性分析采用Pearson相关检验.结果 急性活动期MS组CD8+CD28-T细胞的百分比为(18.48±9.89)%,低于NC组的(24.48±4.86)%(P<0.01),但CD8+CD28+T细胞百分比为(12.23±4.31)%,高于NC组的(8.55±3.49)%(P<0.01),CD8+T细胞的百分比两组比较差异无统计学意义(P>0.05);MS组CD8+CD28-与CD4+CD8-T细胞的百分比呈负相关性(r=0.488,P<0.01);MS患者激素治疗后CD8+CD28-和CD8+CD28+T细胞卣分比与治疗前相比差异无统计学意义(均P>0.05),且治疗后CD8+CD28-T细胞百分比(16.22±4.25)%低于NC组(P<0.01),CD++CD28+T细胞百分比(13.04±4.23)%高于NC组(P<0.01).结论 CD8+CD28-T细胞数日的减少参与了MS的病理过程,并可能通过调节CD4+T细胞起作用;MS急性期激素治疗并不能恢复CD8+CD28-T细胞的数目,激素可能是通过其他途径发生作用.     

粒系集落刺激因子对外周血T淋巴细胞亚群的影响及与CD34+细胞动员效果的相关性

本研究观察粒系集落刺激因子(G—CSF)作为造血干细胞动员剂对外周血T淋巴细胞亚群的影响及与CD34^ 细胞动员效果的关系。对26例行自体造血干细胞移植患在G—CSF动员前后收集外周血标本，用流式细胞术检测动员前后CD3^ 、CD3^ CD4^ 、CD3^ CD8^ 、CD3^ CD4^ CD8^ 及CD3^ CD4^-CD8细胞绝对数量的变化并与外周血CD34^ 细胞的动员效果进行相关性分析。结果表明：GCSF动员后外周血CD3^ 、CD3^ CD4^ 、CD3^ CD4^ CD8^ 及CD3^ CD4^-CD8细胞的绝对数量分别增加2.23，2．62，2.99及10．96倍，而CD3^ CD4^ CD8^ 细胞的变化无统计学意义(P=0．243)。各亚群细胞的变化与CD34^ 细胞动员效果比较，仅CD3^ CD4 CD8细胞的变化与CD34^ 细胞动员效果间具有良好的相关性，r=0．796，P=0.000。结论：G—CSF将造血干细胞由骨髓动员到外周血的同时，使外周血中T细胞亚群的绝对数量发生不同程度的变化。在各T淋巴细胞亚群中CD3^ CD8^-细胞的增加与CD34^ 细胞的动员效果间具有统计学意义的相关性。     

Dendritic cells stimulate primary human cytolytic lymphocyte responses in the absence of CD4+ helper T cells

Cytotoxic lymphocytes are typically generated from unfractionated suspensions of human lymphocytes by stimulating with heterogeneous APCs and exogeneous growth factors. We have found that human blood dendritic cells can directly stimulate allogeneic human CD8+ T cells to proliferate and express antigen-specific cytotoxic activity. These primary responses, which are accompanied by the release of T cell growth factor(s), are induced in the absence of CD4+ helper T cells and are not inhibited by anti-CD4 mAb. Both antigen-specific CTL as well as nonspecific NK cells can be elicited by dendritic cells. The NK cell response can be depleted at the precursor level by panning with an anti-CD11b mAb, which removes a CD11b+/CD28-, CD16+ subset from the starting CD4- responders. Allogeneic blood monocytes are neither stimulatory nor inhibitory of these primary CD4- MLRs, even though monocytes present alloantigen in such a way as to be recognized as specific targets for CTL that have been sensitized by dendritic cells. The number of CD8+ cells that are blast transformed and express an activated phenotype (i.e., HLA DR/DQ+, CD25/IL-2R+, CD45R-) reaches 30-40% of the culture at day 4-5, the peak of the helper-independent response. We conclude that antigen-presentation by dendritic cells is sufficient in itself to prime cytolytic precursors. We speculate that using dendritic cell stimulators and CD4- responders in MLRs may be more efficient than standard tissue typing approaches for the detection of subtle, but important class I MHC-restricted histoincompatibilities in human transplantation.     

Characterization of CD3+, CD4-, CD8- clones expressing the putative T cell receptor gamma gene product. Analysis of the activation pathways leading to interleukin 2 production and triggering of the lytic machinery

Four clones were derived from human peripheral blood T lymphocytes from which CD4+ and CD8+ cells had been removed by treatment with specific mAbs and complement. All expressed the CD2+, 3+, 4-, 8-, T44- phenotype, and did not react with the WT31 mAb, which is specific for a framework determinant of the CD3-associated alpha/beta heterodimer which serves as receptor for antigen on most human T lymphocytes. Surface iodination followed by crosslinking with dithiobis-succinimidyl propionate (DSP) and immunoprecipitation with anti-CD3 mAbs indicated that, in all four clones, the CD3-associated molecules consisted of a major 45 kD band and a minor band of 43 kD. Northern blot analysis showed that mRNA for the gamma chain was expressed at high levels, whereas mRNA for the alpha chain was missing; beta chain mRNA was present in a defective form (1 kb instead of 1.3 kb). These data support the concept that these clones may express, in association with CD3, the molecular product of the T cell receptor gamma genes instead of the typical alpha/beta heterodimer. CD3+, WT31- clones lysed the NK-sensitive K562 target cells and produced IL-2 upon stimulation with PHA. In addition, they released IL-2 after triggering with soluble anti-CD3 mAbs or with an appropriate combination of anti-CD2 mAbs (in the presence of adherent cells). When CD3+, WT31- clones were incubated with an anti-CD3 producing hybridoma as triggering target, the latter was efficiently lysed. Target cell lysis also occurred when a suitable combination of anti-CD2 mAbs-producing hybridomas was used. Therefore, CD3+, WT31- cells appear to use two pathways of cell activation that function also in conventional CD3+, WT31+ T cells, but they lack a third putative pathway initiated by T44 surface molecules.     

Increase of atypical lymphocytes expressing CD4+/CD45RO+ in an infectious mononucleosis-like syndrome associated with hepatitis A virus infection

Subpopulations of regular and atypical lymphocytes in the peripheral blood of a 24-year-old man with an infectious mononucleosis (IM)-like syndrome associated with hepatitis A virus (HAV) infection were analyzed. The ratio of CD4+ to CD8+ cells was in the normal range (1.19 and 1.23 in the regular and atypical lymphocytes, respectively), with no increase in CD8+ cells. The percentage of CD8+/CD11b- cells was not increased in the atypical lymphocytes. However, CD45RO+ was expressed on 86.3% of CD4+ atypical lymphocytes. The present data suggest that atypical lymphocytes expressing CD4+/CD45RO+ may play the role of helper T cells in the immune system in the development of IM-like syndrome associated with HAV infection.     

协同刺激分子CD28/CTLA-4:B7在胃癌患者中的表达及临床意义

目的研究胃癌患者外周血共刺激分子CD28和细胞毒性T淋巴细胞相关抗原-4（CTLA-4，CD152）及B7分子的表达水平，以探讨胃癌患者共刺激通路是否异常以及在胃癌发病机制中的作用。方法用流式细胞仪检测56例胃癌患者外周血淋巴细胞表面的CD28、CD152、CD3、CD4、CD8及B7分子的表达，并与健康对照组及胃良性肿瘤组作比较。结果胃癌患者外周血中CD3^＋、CD4^＋、CD3^＋CD28^＋、B7-1（CD80）、B7～2（CD86）的表达水平及CD4^＋／CD8^＋低于健康对照组及良性肿瘤组，CD3^＋、CD152^＋和CD8^＋水平显著增高。结论胃癌患者外周血淋巴细胞低表达CD28和B7分子，高表达CTLA-4分子，导致了胃癌患者B7：CD28／CTLA-4共刺激通路异常，影响了T细胞彻底清除肿瘤细胞，从而使肿瘤逃避机体的免疫监视、免疫抑制，发生转移。     

Identification of pre-T cells in human peripheral blood. Extrathymic differentiation of CD7+CD3- cells into CD3+ gamma/delta+ or alpha/beta+ T cells

CD7+CD3- cells purified (greater than 99.99%) by FACS from the peripheral blood of healthy adults include precursors for mature T cells that have the capacity to differentiate into TCR-1+ or TCR-2+ CD3+ cells. Extrathymic differentiation was demonstrable from all eight healthy donors in the presence of a high concentration of IL-2, mitogenic levels of PHA, and irradiated blood mononuclear feeder cells, after a lag of approximately 40 d in vitro. The extrathymic T (ET) cells were predominantly TCR-1+, although TCR-2+ cells were also derived. ET TCR-1+ cells were CD4-CD8-, CD4-CD8DIM+, and CD4+CD8-, and were distinguished from natural T TCR-2+ cells by a variety of cell surface markers. The ET cells had phenotypes generally displayed by normal mature T cells, although the CD5DIM+ on ET cells was more typical of thymocytes. Acquisition of CD3 on purified CD7+CD3- cells was not due to antigenic modulation or growth of contaminants, and ET cells could be demonstrated at the clonal level. Studies in athymic mice and bone marrow recipients support the view that extrathymic maturation does occur in vivo. Whether the CD7+CD3- cell population was unexposed to the thymus, or exposed but not processed, is unknown. In any case, unusual or "forbidden" autoreactive specificities are predicted since ET cells differentiate without thymic selection of the TCR.     

健康供者特征对rhG-CSF预激的骨髓采集物CD34+细胞和T细胞亚群的影响

目的 探讨健康供者特征对rhG-CSF预激的骨髓(G-BM)采集物造血和免疫细胞成分的影响.方法 150名健康供者体内应用rhG-CSF 5 μ·kg-1·d-1连续4～5 d,第4,5天采集骨髓和外周血,用流式细胞术测定G-BM采集物中的CD3+、CD3+CD4+、CD3+CD8+、CD14+、CD34+细胞以及CD3+CD4-CD8-调节性T细胞的数量,并分析供者性别、年龄、体重、是否妊娠等特征对G-BM成分的影响.结果 150名健康供者G-BM所含有核细胞,淋巴细胞,CD3+、CD3+CD4+、CD3+CD8+、CD14+、CD34+细胞以及CD3+CD4-CD8-调节性T细胞的中位值分别为31 050(12 200～58 100)、2122(506～6618)、1344(307～4791)、692(145～3038)、616(112～2575)、986(265～2958)、63(11～505)和83(9～390)/μl.年龄≤38岁的供者G-BM中的有核细胞、CD34+细胞以及CD3+ CD4-CD8-调节性T细胞的数量分别为33800(18600～57100)、76(22～505)和97(11～380)/μl,显著高于年龄＞38岁的供者[分别为28 000(12 200～58 100)、49(11～220)和65(9～389)/μl],P值分别为＜0.05,＜0.001和0.001.外周血单核细胞计数＞0.37×109 /L的供者G-BM中有核细胞的数量[33550(12 200～57 100)/μl]显著高于≤0.37×109 /L的供者[27 150(13 800～58 100)/μl](P=0.005).多因素分析显示年龄和外周血单核细胞是G-BM中有核细胞采集量的影响因素[HR值分别为0.41和2.87;P值分别为0.01和0.003];年龄是G-BM中CD34+细胞采集量的唯一影响因素(HR=0.26;P值=0.001);年龄还是G-BM中CD3+ CD4-CD8-调节性T细胞数量的影响凶素[HR值为0.31;P=0.001].结论 年龄是影响G-BM中有核细胞、CD34+细胞和CD3+ CD4-CD8-调节性T细胞采集数量的因素,年龄≤38岁的供者更易采集满足临床需要的有核细胞和CD34+细胞;外周血单核细胞＞0.37×109 /L的供者采集的G-BM含有较多数量的有核细胞.     

Neuraminidase-treated macrophages stimulate allogenic CD8+ T cells in the presence of exogenous interleukin 2

Prior work has shown that purified, resident, and inflammatory peritoneal macrophages are weak stimulators of the allogeneic MLR. We have identified conditions whereby thioglycollate-elicited macrophages become stimulatory, but primarily for the CD8+ T cell subset. The conditions were to treat the macrophages with neuraminidase and to supplement the MLR with rIL-2. These treatments together led to proliferative and cytotoxic responses by isolated CD8+ but not CD4+ T cells. Likewise when MHC-congenic strains were evaluated, an MLR was observed across isolated class I but not class II MHC barriers. Pretreatment of the macrophages with IFN-gamma further enhanced expression of class I MHC products and stimulatory activity, but did not seem essential. While these treatments did not render macrophages stimulatory for an MLR in purified CD4+ cells, blastogenesis of CD4+ cells was observed when the MLR involved bulk T cells. Small allogeneic B lymphocytes behaved similarly to macrophages, in the pretreatment with neuraminidase and supplementation with rIL-2 rendered B cells stimulatory for allogeneic, enriched, CD8+, but not CD4+, T cells. Spleen adherent cells, which are mixtures of macrophages and dendritic cells, stimulated both CD4+ and CD8+ T cells, and neither neuraminidase nor exogenous IL-2 was required. We think that these data suggest that most macrophages and small B cells lack three important functions of dendritic cells: a T cell-binding function that can be remedied by neuraminidase treatment, a T cell growth factor-inducing function that can be bypassed with exogenous IL-2, and an IL-2 responsiveness function that is required by CD4+ lymphocytes.     

T lymphocyte differentiation in vitro from adult human prethymic CD34+ bone marrow cells

Pluripotent lymphohematopoietic stem cells are probably confined to bone marrow cells expressing CD34 surface molecules. To investigate the capacity of adult human CD34+ bone marrow cells to differentiate along the T lymphoid lineage, we plated purified CD34+ cells from healthy adults in liquid culture on adherent thymic stromal cells prepared from HLA- or blood group-mismatched postnatal thymic tissue. We show that purified CD34+CD3-CD4-CD8- bone marrow cells contained progenitors with the ability to differentiate into CD4+ and CD8+ T lymphocytes expressing surface (s)CD3 and T cell receptor alpha/beta in vitro. These progenitors were found in the CD34+CD2+sCD3-CD4-CD8-, CD34+CD7+sCD3-CD4-CD8-, and CD34+CD2+CD7+sCD3-CD4-CD8-, as well as in the CD34+CD2-sCD3-CD4-CD8-, CD34+CD7-sCD3-CD4-CD8-, and CD34+CD2-CD7- sCD3-CD4-CD8- subsets, indicating that T lymphocyte progenitors sensitive to signals mediated by thymic stroma in vitro are not restricted to CD34+ cells already coexpressing early T lymphocyte- associated markers. Finally, we show that T lymphopoiesis was enhanced by c-kit ligand.     

免疫磁珠正负筛选在分离外周血CD8+和 CD4+T细胞亚群中的应用

为了探讨免疫磁珠分离技术及其正、负筛选策略在人外周血T淋巴细胞亚群分离提纯中的应用,应用补 体细胞毒法和正负筛选策略相结合的免疫磁珠法分离健康人外周血中CD4 T细胞、CD8 T细胞;用流式细胞术法 比较两种分离方法分离的靶细胞纯度;台盼蓝染色染色法和细胞培养后平板计数法检测免疫磁珠法分离的CD4 T 细胞、CD8 T细胞的活力和生长情况。结果表明:补体细胞毒法分离后CD4 T细胞纯度、CD8 T细胞纯度分别为 (76.0±2.8)％和(77.0±3.0)％,明显高于分离前的(34.6±3.7)％和(32.0±3.7)％(P<0.05);免疫磁殊法 分离后CD4 T细胞和CD8 T细胞纯度为(94.2±1.4)％和(93.8±3.0)％,显著高于补体细胞毒法(P<0.05)。 磁珠分离法获得的CD4 T细胞、CD8 T细胞细胞活力分别为(96.0±2.4)％和(95.0±3.6)％;细胞计数法表明 磁珠分离法获得的CD4 T细胞、CD8 T细胞对植物血凝素(PHA)的刺激保持了良好的增殖能力。结论:免疫磁珠 法较补体细胞毒法分离效率高,不影响细胞的活力和增殖能力;正负筛选策略相结合的免疫磁珠法在同时获取高 纯度的CD4 T细胞、CD8 T细胞时可获得满意效果,尤其适应于只有较少量血标本的情况,为进一步研究CD4 T 细胞、CD8 T细胞的生物学特性创造了条件。     

SARS患者白细胞及T细胞亚群的变化

[目的]探讨严重急性呼吸综合征(SARS)患者外周血白细胞和T淋巴细胞亚群的变化及其临床意义。[方法]用全自动血细胞分析仪检测44例SARS患者外周血白细胞计数及分类．用流式细胞仪检测SARS患者外周血T淋巴细胞亚群;并与正常对照组比较。[结果]与对照组比较．SARS组患者白细胞总故显著下降,淋巴细胞百分数和绝对数显著下降．粒细胞绝对数显著下降,粒细胞百分数显著增如：CD、CD2^-和CD8^-细胞绝对数显著下降,CD3^-、CD4^-、CD8^-细胞百分数和CD4^-／CD8^-比值与对照组比较无显著性差异。1年后,恢复期SARS患者的上述各项指标均恢复正常。[结论]SARS冠状病毒感染损伤患者中性粒细胞和细胞免疫功能,但这种损伤是可逆的。     

肾移植急性排斥反应时B7-2/CD28信号通路的表达

背景:以往动物研究表明,在器官移植急性排斥反应时共刺激分子的表达与急性排斥反应密切相关.目的:观察急性排斥反应时患者移植肾脏组织和外周血中B7-2/CD28信号通路的表达.方法:对53例同种异体肾移植患者于移植前1 d、移植后1,3,7,14,21,28 d分别取外周血以及在临床诊断急性排斥反应当天和抗排斥治疗1周后额外采血,用流式细胞仪检测共刺激分子B7-2/CD28在外周血淋巴细胞中的表达;同时,行经皮肾穿刺活检供肾修整结束时、移植后7 d、1个月、6个月、1年或以上获取活检肾脏组织,用免疫组织化学方法检测活检组织中B7-2/CD28的表达情况.结果与结论:移植后1,3 d内所有患者外周血中CD28+,CD4+/CD28+,CD8+/CD28+细胞比率均有显著下降(P < 0.05),一二周后恢复到术前水平;移植后7 d未发生急性排斥反应的患者肾脏组织B7-2阳性表达率显著上升(P < 0.05),1个月后下降至移植前水平(P > 0.05).移植后发生急性排斥反应的患者外周血CD28+,CD4+/CD28+,CD8+/CD28+细胞比率及肾脏组织B7-2阳性表达率明显上升(P < 0.05),经抗排斥治疗1周后均好转.结果证实,在肾移植后出现急性排斥反应时,肾脏组织以及外周血中共刺激分子B7-2/CD28的表达上调与急性排斥反应的发生密切相关.     

CD4+CD25+ suppressor lymphocytes in the circulation of patients immunized against melanoma antigens

Murine studies have suggested that a population of CD4+ T cells expressing the alpha chain of the interleukin (IL)-2 receptor (CD25+) are phenotypically anergic in response to T cell receptor stimulation and can suppress the function of CD4+ and CD8+ T cells. Recent studies of peripheral lymphocytes from healthy human volunteers have identified a similar population, although little is known about the presence and activity of these cells in patients with cancer and their possible impact on anticancer immunization strategies. Thus, the authors have undertaken these studies in patients with metastatic melanoma undergoing immunizations with known melanoma antigens. CD4+ CD25+, CD4+ CD25-, and a 1:1 ratio of these isolated T cells were stimulated with soluble anti-CD3 antibody in the presence of irradiated T cell-depleted PBMCs, and proliferation was assessed by measuring [3H]thymidine incorporation. In 13 patients, isolated CD4+CD25+ T cells proliferated 68% (+/- 5.8%) less than separately cultured CD4+ CD25- T cells. Moreover, CD4+ CD25+ T cells suppressed the proliferation of an equal number of cocultured CD4+ CD25+ T cells in 11 of 13 patients by an average of 60% (+/- 4.9%). Suppression was not seen at day three of culture and became apparent at days five through nine. The degree of suppression was proportional to the numbers of CD4+ CD25+ T cells. Addition of high-dose IL-2 reversed the hypoproliferative phenotype of the CD4+ CD25+ T cells and abrogated their suppressive function. These studies demonstrate that anergic and functionally suppressive CD4+ CD25+ T cells exist in patients with melanoma undergoing tumor antigen immunization and thus may play a role in modifying the magnitude of the T cell response to immunization.     

Phenotypic and functional characterization of human cytolytic T cells lacking expression of CD5.

Although the CD5 (T1) antigen was initially described as a pan-T cell membrane glycoprotein, we report that 14 of 40 normal individuals were found to have 5% or greater of their blood mononuclear cells characterized as CD3 (T3)+ but CD5- by dual immunofluorescence flow cytometry. These cells expressed normal quantities of surface CD3 and CD2 but low levels of CD7, were CD8+ and CD4-, and CD16-. In order to determine whether cells of this phenotype were functional, six CD5- cytolytic T lymphocyte (CTL) clones isolated from normal individuals were studied. The CD5- CTL clones all demonstrated normal cytolytic activity against appropriate target cells. Monoclonal antibodies (MAbs) directed against CD3, CD8, CD2, and lymphocyte function-associated antigen 3, but not against CD5, inhibited cytolytic activity. Changes in intracellular calcium [( Ca2+]i) in response to anti-CD5 and anti-CD3 MAbs were measured. Stimulation by anti-CD5 MAb alone did not give rise to a change in [Ca2+]i. However, under conditions of limiting concentrations of anti-CD3 MAb, preincubation of normal CD5+, but not CD5-, clones with anti-CD5 MAb led to a dramatic enhancement in the ability of anti-CD3 MAb to elicit a rise in [Ca2+]i. We conclude that CD5- T lymphocytes represent a normal lymphoid phenotype. Although CD5 may be involved in T cell activation when present, these CD5- CTL clones appear to express normal cytolytic activity.     

Characterization of mononuclear cells remaining in the leukoreduction system chambers of apheresis instruments after routine platelet collection: a new source of viable human blood cells

BACKGROUND: The yield of white blood cells (WBCs) extracted from whole-blood leukoreduction filters can be affected by the storage conditions and delay before filtration. Platelets (PLTs) collected with apheresis instruments (Trima Accel, Gambro BCT) are leukoreduced during the procedure on a fluidized particle bed in a leukoreduction chamber (LRS chamber). In this report, the residual cell content of these LRS chambers was characterized to determine whether it would be a valuable source of viable human blood cells. STUDY DESIGN AND METHODS: The content of LRS chambers was eluted by gravity, and peripheral blood mononuclear cells (PBMNCs) were purified on a Ficoll-Paque gradient. Analyses were performed before and after freezing. Proportions of CD3+, CD14+, CD16+, CD19+, CD34+, and CD45+ cells were determined by flow cytometry. The frequency of T cells expressing CD4, CD8, and CD27 and of B cells expressing immunoglobulin G (IgG), IgM, and CD27 was also determined. RESULTS: LRS chambers held approximately 10(9) CD45+ cells representing the normal proportions of CD3+, CD14+, CD16+, and CD19+ cell populations of PBMNCs. A small fraction of these CD45+ cells were CD34+CD38+ cells (0.3 +/- 0.2%). The viability of these cells, measured before and after freezing, was more than 95 percent. CONCLUSION: The residual cell content of Trima Accel LRS chambers recovered after PLT collection is a good source of viable monocytes and lymphocytes. These PBMNCs, containing CD3+, CD14+, CD16+, CD19+, and CD34+ cells can be frozen to prepare cell banks, which opens new avenues for utilization in several physiologic studies or even in cellular therapy applications.     

Functional consequences of interleukin 2 receptor expression on resting human lymphocytes. Identification of a novel natural killer cell subset with high affinity receptors

In this study, we have used radiolabeled IL-2 binding assays, Northern blot analysis, immunofluorescent flow cytometry and cell sorting, as well as proliferation and cytotoxicity assays to perform an extensive phenotypic and functional characterization of the IL-2 receptor in normal resting human peripheral blood lymphocytes. Our results indicate that almost all T cells (greater than 98%) express neither the high affinity IL-2 receptor nor the functional intermediate affinity p75 chain of the IL-2 receptor without prior activation. In contrast, most NK cells constitutively express the isolated intermediate affinity p75 IL-2 receptor. In addition, a subpopulation of NK cells, distinguished by high density expression of the NKH1 antigen, constitutively express the high affinity IL-2 receptor, in addition to an excess of the isolated intermediate affinity p75 IL-2 receptor. These NKH1bright+ cells exhibit a brisk proliferative response to IL-2, similar to that seen with antigen-activated T cells, yet do so in the absence of any known antigenic stimuli. No other resting peripheral blood lymphocyte population, including CD4+, CD8+, and CD20 cells, exhibits this property. The intermediate affinity p75 IL-2 receptor, as it exists in its isolated form on resting NK cells, does not transduce a growth signal equivalent to that seen in NK cells expressing the high affinity IL-2 receptor, despite doses of IL-2 that are known to fully saturate the isolated p75 chain. This strongly suggests that additional structural or functional components are involved in generating the proliferative response following the binding of IL-2 to the high affinity heterodimeric form of the IL-2 receptor. The constitutive expression of this functional high affinity IL-2 receptor on a small population of resting NK cells provides further evidence in support of a role for these cells in the host's early defense against viral infection or malignant transformation, before the more delayed but specific T cell response.