Dual expression of CD45RA and CD45RO isoforms on myelin basic protein-specific CD4+ T-cell lines in multiple sclerosis

Myelin basic protein (MBP)-specific T-cell lines from patients with multiple sclerosis (MS) and healthy controls were analyzed for the expression of CD45 isoforms and adhesion molecules. In the multiple sclerosis group, 22 of 24 MBP-specific T-cell lines were CD4+. Two distinct patterns were observed with regard to CD45 isoform expression. Pattern I showed dual expression of CD45 isoforms (CD4+CD45RA+CD45RO+CD29+) and Pattern II included cells with a single CD45 isoform (CD4+CD45RA–CD45RO+CD29+). All 10 cell lines from healthy controls were CD4+ and displayed Pattern II (CD4+CD45RA–CD45RO+CD29+). The dual expression of CD45 isoform in T-cell lines from MS was stable, did not represent a transition stage from CD45RA to CD45RO, and was cell-cycle independent. All cell lines from MS and controls expressed increased levels of LFA-1 (CD11a), LFA-2 (CD2), LFA-3 (CD58), ICAM-1 (CD54), and VLA-4 (CDw49d). These data show the presence of unique MBP-specific T cells (CD4+CD45RA+CD45RO+CD29+) that might play a role in the pathogenesis of MS.     

Distribution of CD45RA and CD45RO T-lymphocyte subsets in rheumatoid arthritis synovial tissue

We have characterized the lymphocytes in the synovium of patients with rheumatoid arthritis (RA) by immunohistochemistry using monoclonal antibodies directed against B lymphocytes, T lymphocytes, and antibodies directed against CD45RA and CD45RO, which define T-cell subsets. Both CD45RA+ and CD45RO+ T lymphocytes were detected in the perivascular regions. CD45RA+ lymphocytes were present primarily in perivascular areas of moderate to large lymphocytic infiltration. Some synovial perivascular lymphocytic aggregates were organized into focal areas of CD45RA+ B lymphocytes surrounded by CD45RO+ T lymphocytes. In areas of diffuse lymphocytic infiltration, the T lymphocytes were CD45RO+. These data suggest that both CD45RO+ and CD45RA+ T lymphocytes enter the RA synovial tissue via the synovial vasculature and that, once in the tissue, the CD45RA+ T lymphocytes may undergo activation/maturation and acquire the CD45RO phenotype.     

CD8+ T-cell subsets defined by expression of CD45 isoforms differ in their capacity to produce IL-2, IFN-gamma and TNF-beta.

Expression of different isoforms of CD45, the leucocyte common antigen (LCA), on T-cell subsets has permitted distinctions between the functional activities of subpopulations within the major CD4+ T-cell subset. With respect to cytokine production, the expression on CD4+ cells of CD45RA, a high molecular weight isoform, defines a population which produces only interleukin-2 (IL-2) and tumour necrosis factor-beta (TNF-beta) in quantity, with peak production of IL-2 occurring after 24-48 hr stimulation, while the CD4+ population bearing high levels of CD45RO, a low molecular weight isoform, can produce a wide range of cytokines within 24 hr of activation. The literature is conflicting on the capacities for cytokine production of CD8+ subsets divided on the basis of either CD45RA or CD45RO expression. The aim of this study was to attempt to clarify this area by determining the amount and kinetics of production of IL-2, interferon-gamma (IFN-gamma) and TNF-beta in CD8+ cells separated on the basis of both CD45RA and CD45RO isoform expression. The results showed that CD8+ CD45RA- and CD8+ CD45RO+ T lymphocytes produce significantly more of all three cytokines than do CD8+ CD45RA+ or CD8+ CD45RO- T cells. The kinetics for IFN-gamma and TNF-beta production were similar for both subsets, while IL-2 production was delayed by approximately 3 hr in the CD8+ CD45RO- population as compared to the CD8+ CD45RO+ subset. It is suggested that some of the confusion over cytokine production by these CD8+ subsets may be attributable to different conditions for isolation causing pre-activation of positively selected populations. It is also suggested that while CD8+ CD45RA+ cells are shown to acquire CD45RO upon activation, as do CD4+ CD45RA+ cells, the results of the present study argue for a different relationship between CD8+ subsets separated on the basis of CD45 isoform expression than between the corresponding CD4+ subsets.     

蕈样肉芽肿患者外周血单一核细胞CD45RA及CD45RO表达的研究

目的探讨蕈样肉芽肿（Mycosis fungoides,MF）患者外周血单个核细胞CD45RA及CD45RO的表达及其与MF发病的关系。方法应用双荧光抗体标记、流式细胞仪检测15例MF患者外周血单个核细胞CD45RA及CD45RO的表达。结果（1）MF患者外周血CD3^＋、CD3^＋CD8^＋细胞与正常对照比较差异不显著（P〉0.05）。（2）MF患者外周血CD4^＋细胞低于正常对照,差异非常显著（P〈0.001）。（3）MF患者外周血T细胞CD3^＋CD4^＋/CD3^＋CD8^＋比值低于正常对照,差异显著（P〈0.001）。（4）MF患者外周血CD45RA^＋细胞低于正常对照,差异非常显著（P〈0.001）,CD45RO^＋细胞高于正常对照,差异非常显著（P〈0.001）。（5）MF患者外周血CD45RO^＋/CD45RA^＋比值高于正常对照,差异非常显著（P〈0.001）。（6）MF患者外周血CD4^＋CD45RA^＋细胞低于正常对照,差异非常显著（P〈0.001）。（7）MF患者外周血CD4^＋CD45RO^＋细胞及CD8^＋CD45RO^＋细胞均高于正常对照,差异非常显著（均P〈0.001）。（8）MF患者外周血CD4^＋CD45RO^＋/CD4^＋CD45RA^＋比值及CD8^＋CD45RO^＋/CD8^＋CD45RA^＋比值均高于正常对照,差异非常显著（P〈0.01及P〈0.001）。结论MF患者外周血中,不仅存在CD4^＋亚群失调和CD4^＋/CD8^＋比值降低,而且在CD4^＋和CD8^＋亚群中也存在CD45RA^＋、CD45RO^＋亚群失调和CD45RO^＋/CD45RA^＋比值升高,从而导致的机体免疫功能紊乱,可能与MF的发病或病情加剧有关。     

Loss of CD45RA and gain of CD45RO after in vitro activation of lymphocytes from HIV-infected patients.

T-lymphocyte activation is accompanied by a loss of CD45RA determinant and gain of CD45RO marker. Previous work suggests that the CD45RO population could represent the T-cell memory pool since it contains most of the cells that can respond to recall soluble antigens. A selective loss of memory T cells was recently found in early stages of human immunodeficiency virus (HIV) infection, which could contribute to the qualitative defects observed in HIV-infected patients. In order to investigate whether HIV infection could induce an alteration in the process of differentiation from naive cells to cells with a memory phenotype, we studied the expression of CD45RA and CD45RO in CD4+ and CD8+ lymphocytes, by flow cytometric analysis, after mitogenic stimulation of mononuclear cells from patients with HIV infection. These preliminary results suggest that after in vitro activation the CD4+ and CD8+ populations from HIV-infected patients lose the CD45RA marker and concomitantly acquire the CD45RO determinant in the same way as shown for the healthy control population studied simultaneously. Thus, it appears that an alteration in the process of conversion of CD45RA into CD45RO does not contribute to the defects observed in the memory T-cell population in HIV infection.     

Loss of activation-induced CD45RO with maintenance of CD45RA expression during prolonged culture of T cells and NK cells.

The results of the present study show that activation-induced changes in CD45RA and CD45RO expression on T cells and natural killer (NK) cells are not unidirectional for all cells during a 5-week culture period. T cells and NK cells were generated from a resting subpopulation of peripheral blood mononuclear cells (PBMC) defined by sedimentation at Percoll high buoyant densities (p greater than 1.0640 g/ml) and unresponsiveness to IL-2. T cells were activated by a combination of PHA, sheep erythrocytes and IL-2-conditioned medium (IL-2-CM), and NK cells were activated by co-culture with gamma-irradiated malignant melanoma (MM-170) cells and IL-2-CM. Both T-cell and NK-cell cultures were maintained by subculture in IL-2-CM. NK cells and the CD45R(Abright)RO(dim/neg) subpopulation of T cells gained CD45RO following activation and this was accompanied by a two-fold decrease in CD45RA expression. In different cultures, CD45RO expression was not stable on 28-80% of T cells and 10-55% of NK cells. Cells with decreased CD45RO expression showed increased expression of CD45RA. Instability of CD45RO expression on cultured T cells and NK cells occurred at a time following the period of rapid cell growth when the cells were entering a quiescent phase. Both the CD4+ and CD8+ T-cell subpopulation showed similar changes in CD45 isoform expression. In contrast to the results obtained with the CD45R(Abright)RO(dim/neg) resting T cells, the CD45RO(bright)RA(dim/neg) subpopulation of resting T cells when activated and cultured under identical conditions retained CD45RO expression and remained CD45RAdim/neg. Thus a significant proportion of resting CD45R(Abright)RO(dim/neg) T cells is not related in a differentiation sequence to resting CD45RObrightRAdim/neg T cells, and therefore resting CD45RAbrightROdim/neg T cells and resting NK cells may be heterogeneous with respect to their activation history.     

Phenotypic switch from CD45RA+ to CD45RA- by normal blood T cells is associated with increased HLA-ABC expression for CD4+ and CD8+ populations but not for the NK-associated CD4-CD8dim+ or CD4-CD8- fractions.

Using the combined techniques of immunomagnetic depletion and multiple colour flow cytometry, the expression of HLA-ABC (W6/32) by normal T-cell subpopulations, defined by 2H4 (CD45RA) expression, was examined. It is thought that a CD45RA+CD45RO- phenotype defines the 'virgin' T-cell fraction, whereas a CD45RA-CD45RO+ phenotype defines the 'primed' or memory T-cell population. In addition, an intermediate phenotype (CD45RA+CD45RO+) appears to correspond to a transitional stage of development. In this study, these three phenotypic stages were represented by distinct levels of 2H4 staining defined as 2H4+, 2H4int and 2H4-, respectively. The results of this current investigation are of importance in two main areas. Firstly, when compared to the 2H4+ component, the HLA-ABC expression of 2H4- cells was significantly higher. This was true for both CD4+CD8- and CD4-CD8+ lymphocytes, but was not the case for CD4-CD8dim+, CD3+CD4-CD8- and CD3-CD4-CD8- fractions. Additionally, when HLA-ABC expression was examined as a function of 2H4 staining intensity, it was found that, for the CD4+ fraction, the greatest increase in HLA-ABC expression occurred between the 2H4int and 2H4- stages. In contrast, the increase in HLA-ABC expression by CD8+ lymphocytes was associated with transition from 2H4+ to 2H4int status, which suggests that increased HLA-ABC expression occurs at an earlier stage in the acquisition of CD45RO in CD8+ cells than for CD4+ cells. Secondly, for each individual blood examined, a close and highly significant correlation (P = 0.002) for membrane HLA-ABC expression was found between (i) CD4+2H4+ and CD8+2H4+ and (ii) CD4+2H4- and CD8+2H4- subpopulations. This suggests that modulation of HLA-ABC expression in CD4+ and CD8+ cells is subject to common control mechanisms and remains proportionate for these lymphocyte fractions in any given individual.     

Phenotypical and Functional Differentiation of CD4+ CD45RA+ Human T Cells Following Polyclonal Activation

Human CD4+ T cells differ in their expression of the leucocyte common antigen. Antibodies detecting certain forms (CD45RA and CD45RO) of this antigen have been used to identify and isolate subpopulations of the CD4+ T cells. These isolated subsets have been shown to have different abilities concerning lymphokine production and provision of help to B cells for Ig production. When these T-cell subsets were activated in vitro with polyclonal activators, the production. When these T-cell subsets were activated in vitro with polyclonal activators, the CD45RA+ cells lost this marker and gained the expression of CD45RO. This was true for all mitogens used in this report, i.e. accessory cell-dependent stimulation with SEA and accessory cell-independent activation with PMA or PHA. A correlation between proliferation and differentiation was observed, but this was probably not causative as stimulation with PMA in the absence of DNA synthesis resulted in the acquisition of CD45RO and loss of the CD45RA antigen. Moreover, cells proliferating vigorously for long periods of time expressed both markers at significant levels, which suggests that proliferation did not automatically result in complete loss of the CD45RA marker. The phenotypical differentiation was associated with a functional differentiation which induced the stimulated cells' ability to act as helper cells for Ig production and to produce gamma interferon (IFN-gamma). The results obtained in this study support the contention that the CD45RA+ cells are precursors of the CD45RO+ cells and that the two subsets represent different maturational stages of the same lineage.     

CD45 isoform expression during T cell development in the thymus.

Various isoforms of leukocyte common antigen, or CD45, are expressed differentially on T cells at different stages of development and activation. We report studies on CD45 isoform expression on various subsets of human T cells using two- and three-color flow cytometry and cell depletion. Bone marrow cells that were depleted of CD3+ and HLA-DR+ cells were CD45RA-RO-. The earliest CD3-CD4-CD8-CD19- thymocytes were CD45RO- with 20%-30% CD45RA+ cells. The most prominent population of CD4+CD8+ double-positive thymocytes were CD45RA-RO+. Even the CD4+CD8+ blasts were greater than 90% CD45RO+. About 80% of single-positive thymocytes (CD4+CD8- or CD4-CD8+) were also CD45RO+. Only 4.3% of CD4+ and 18% of CD8+ single-positive thymocytes were CD45RA+. In contrast, cord blood T cells which represent the stage that immediately follows single-positive thymocytes, contained 90% CD45RA+ cells. Thus, in terms of CD45 isoform expression, single-positive thymocytes are more like double-positive cells than cord blood T cells. These results suggest the following sequence of CD45 isoform switching during T cell development: CD45RA-RO- or RA+RO- (double-negative thymocytes)----RA-RO+ (double-positive and most single-positive thymocytes)----RA+RO- (cord blood T cells), the last switch from CD45RO to CD45RA occurring as a final step of maturation in the thymus.     

CD45 isoform phenotypes of human T cells: CD4(+)CD45RA(-)RO(+) memory T cells re-acquire CD45RA without losing CD45RO

We have studied the alterations in CD45R phenotypes of CD4(+)CD45RA(-)RO(+) T cells in recipients of T cell-depleted bone marrow grafts. These patients are convenient models because early after transplantation, their T cell compartment is repopulated through expansion of mature T cells and contains only cells with a memory phenotype. In addition, re-expression of CD45RA by former CD4(+)CD45RA(-) T cells can be accurately monitored in the pool of recipient T cells that, in the absence of recipient stem cells, can not be replenished with CD45RA(+) T cells through the thymic pathway. We found that CD4(+)CD45RA(-)RO(+) recipient T cells could re-express CD45RA but never reverted to a genuine CD4(+)CD45RA(+)RO(-) naive phenotype. Even 5 years after transplantation, they still co-expressed CD45RO. In addition, the level of CD45RA and CD45RC expression was lower ( approximately 35 %) than that of naive cells. In contrast, the level of CD45RB expression was comparable to that of naive cells. We conclude that CD4(+)CD45RA(-)RO(+) T cells may re-express CD45(high) isoforms but remain distinguishable from naive cells by their lower expression of CD45RA / RC and co-expression of CD45RO. Therefore, it is likely that the long-lived memory T cell will be found in the population expressing both low and high molecular CD45 isoforms.     

Evaluation of thymopoiesis using T cell receptor excision circles (TRECs): differential correlation between adult and pediatric TRECs and naïve phenotypes

To determine whether the thymus is still functional despite age-related involution, we measured a biomarker for thymopoiesis known as the T cell receptor excision circle (TREC) from peripheral blood mononuclear cells (PBMCs) of 148 healthy children and from PBMCs, CD4(+), and CD8(+) cells of 32, 30, and 50 healthy adults, respectively. We demonstrate that during the first 5 years of life, thymic output is decreased (P 0.002) but not dramatically (r = -0. 282). Among adults aged 23-58, thymic output was inversely correlated with age, as measured from PBMCs (r = -0.628, P < 0.0005), CD4(+) (r = -0.530, P 0.003), and CD8(+) fractions (r = -0.385, P 0. 006). A strong correlation existed between pediatric PBMC TRECs and the expression of three na?ve phenotypic markers (CD45RA(+)CD45RO(-), CD45RA(+)CD62L(+), and CD45RO(-)CD27(+)CD95(low)). Adult PBMC TRECs correlated only with the expression of CD45RA(+)CD45RO(-) (r = 0.459, P 0.012). Our data suggest that in adults CD45RA(+)CD45RO(-) may be enriched for TRECs and add to a growing body of evidence illustrating intact thymic function in adulthood.     

Assessment of thymic output in common variable immunodeficiency patients by evaluation of T cell receptor excision circles

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by repeated infections and hypogammaglobulinaemia. Additionally, T-cell abnormalities including lymphopenia, decreased proliferation to mitogens and antigens, and the reduced production and expression of cytokines, have also been observed. In this study we have investigated the expression of naive, memory and activation markers in T-cell subpopulations in 17 CVID patients in comparison to age-matched normal controls. The numbers of CD4+ T cells, including CD45RA+CD62L+ and, to a lesser extent, CD45RA-CD62L+/RA+CD62L- were significantly reduced in patients, whereas CD8+ T cells were within normal range. In contrast, HLA-DR+ cells were increased both in CD4+ and CD8+ T cells. To assess the thymic output, we analysed the presence of T-cell receptor excision circles (TRECs) in CD4+ and CD8+ T cells by quantitative PCR. TRECs were decreased significantly in patients and the rate of TREC loss was higher with increasing age. TRECs correlated with naive CD4+ T cells, whereas there was an inverse relationship between TRECs and CD8+HLA-DR+ and CD8+CD45RA-CD62L+/RA+CD62L- T cells. Our results suggest the presence of a defect in the naive T cell compartment with origin at the thymic level in CVID, and indicate that TREC may be a useful marker to monitor thymic function in this primary immunodeficiency.     

Differential expression of the cytokine receptors for human interleukin (IL)-12 and IL-18 on lymphocytes of both CD45RA and CD45RO phenotype from tonsils, cord and adult peripheral blood

The objective of this study was to demonstrate the variable expression of cytokine receptors on naive versus memory human CD4+ T cell subpopulations in tonsillar tissue, cord blood and adult blood. We prove that the receptors for both interleukin (IL)-12 and IL-18 are expressed exclusively on memory T cells. This observation was seen not only on the CD45RO+ memory T cells but also on a significant percentage of the CD45RA+, CD62L-, CD27- and CCR7- populations. Furthermore, CD45RA+ CD62L+, CD27+ or CCR7+ CD4+ T cells that expressed IL-12Rbeta1 and IL-18Ralpha did not express CD31, a marker for recent thymic emigrants. We reveal that cord blood lymphocytes do not express IL-12Rbeta1 whereas IL-18Ralpha expression was detected at low levels. Importantly, the IL-12Rbeta2 signalling chain, which is absent in all resting T cells, was up-regulated in both CD45RA+ and CD45RO+ T cells as a result of stimulation with anti-CD3 and anti-CD28 in vitro. This observed up-regulation was, however, restricted to 80% of the total CD4+ population. Finally, a very small proportion of the CD4+ CD45RO+ tonsillar T cells expressed the IL-12 and IL-18 receptors, thereby establishing the differential expression of these receptors between peripheral and tonsillar memory T cell subpopulations.     

CD31 (PECAM-1) is a differentiation antigen lost during human CD4 T-cell maturation into Th1 or Th2 effector cells.

The CD31 antigen (PECAM-1) has been reported to be a stable marker for a human CD4 T-cell subpopulation unable to produce interleukin-4 (IL-4). We show here that CD31 expression is not stable inasmuch as CD4 T-cell lines and clones derived from cell-sorted neonatal CD31+ cells lose CD31 upon repetitive cycles of stimulation and IL-2 expansion. Moreover, various cytokines (IL-1 alpha, IL-4, IL-6, transforming growth factor-beta) fail to reinduce CD31 on CD31- clones. Whereas all CD31+ CD4 T cells rapidly express high levels of the CD45RO antigen and down-regulate the L-selectin antigen after priming, CD31 disappears more slowly because only part of the cells lose CD31 expression upon each cycle of stimulation. Loss of CD31 reflects a functional maturation of CD45RO+ cells since, in a system which favours the development of Th2 effectors, IL-4 is produced by CD31- but not CD31+ effector T cells, whereas interferon-gamma is produced by both types of cells. However, CD31 is not a Th1 marker since it is not expressed on several Th1 antigen-specific clones. We conclude that CD31 is a maturation marker expressed on the great majority of naive CD45RO- CD4 T cells and on a subset of CD45RO+ CD4 T cells that are at an intermediate stage of maturation.     

Intraepithelial TcR alpha/beta+ lymphocytes express CD45RO more often than the TcR gamma/delta+ counterparts in coeliac disease.

Expression of CD45RO on intraepithelial lymphocytes (IEL) bearing the T-cell receptor (TcR) alpha/beta or gamma/delta was studied in situ by three-colour immunofluorescence on jejunal tissue sections from 21 patients with coeliac disease and eight controls. CD45RA-TcR alpha/beta+ IEL expressed CD45RO significantly more often (75%) than the preferentially expanded TcR gamma/delta+ counterpart (59%). Triple staining for CD3, CD4/8 and CD45RA or CD45RB revealed that all CD3 + 4 - 8 - IEL (taken to be TcR gamma/delta+) expressed CD45RB and none were CD45RA. CD45RO positivity was of the same magnitude (66%) on the predominating monoclonal antibody delta TCS1-reactive fraction of TcR gamma/delta+ cells as on the remainder of the TcR gamma/delta+ subset. These results suggest that gluten exposition in patients with coeliac disease leads to accumulation of CD45RA-, putative antigen-primed memory cells of both TcR phenotypes. The less marked CD45RO expression within the preferentially expanded TcR gamma/delta+ subset of IEL may be of particular biological interest.     

Rapid conversion of naive to effector T cell function counteracts diminished primary human newborn T cell responses.

The reduced incidence of graft versus host disease following the use of human cord blood as a source of stem cells for bone marrow reconstitution challenges our understanding of the immunocompetence of newborn T cells. Newborn CD4+ T cells express mainly the CD45RA phenotype and have been considered to respond comparably to adult CD4+ T cells exhibiting the CD45RA phenotype. We compared the in vitro kinetics of phenotypic conversion of newborn and adult CD4+CD45RA+ T cells to CD4+CD45RO+ T cells. The cytokine profile and B cell helper activity of the converted CD4+CD45RO+ T cell population were also determined. Newborn CD4+CD45RA+ T cells were converted to CD4+CD45RO+ with significantly faster time kinetics than adult CD4+CD45RA+ T cells, following either phytohaemagglutinin (PHA) or anti-CD2 activation. Freshly purified newborn naive T cells did not produce IL-2, IL-4 or interferon-gamma (IFN-gamma) following stimulation, whereas adult naive T cells secreted IL-2 and adult-derived CD4+CD45RO+ T cells secreted all three cytokines under the same stimulatory conditions. However, newborn and adult CD4+CD45RA+ T cells, following primary stimulation and maturation in vitro, acquired the ability to secrete a Th1-type cytokine profile of IL-2 and IFN-gamma after secondary stimulation. Newborn CD4+ naive T cells that acquired the CD45RO phenotype in vitro also gained B cell helper activity equivalent to that of adult in vitro matured CD4+ naive T cells. These findings suggest that newborn and adult CD4+CD45RA+ T cell subsets are differentially responsive to various stimuli. They show that newborn CD4+CD45RA+ naive T cells can transform more quickly than their adult counterparts into functionally equivalent CD4+CD45RO+ T cells, a process that may be important to counteract the immature immune environment which exists in the newborn.     

结直肠癌患者与健康受试者外周血CD45RA+/CD45RO+淋巴细胞表型分析

目的 分析结直肠癌患者与健康受试者外周血CD45RA+/CD45RO+系列T淋巴细胞表达的差异.方法 运用流式细胞术(FCM)检测2010年1月至2013年12月解放军总医院收治的109例结直肠癌患者(试验组)与64例健康受试者(对照组)外周血CD45RA+、CD45RO+、CD4+ CD45RA+、CD4+ CD45RO+T淋巴细胞亚群表达情况,统计分析试验组和对照组性别和年龄的分布是否存在差异,然后进一步分析CD45 RA等T淋巴细胞亚群与结直肠癌临床分期的关系.结果Ⅰ+Ⅱ期、Ⅲ期和Ⅳ期结直肠癌患者外周血CD45 RA+细胞百分率[三者分别为(56.23±7.75)％、(58.86±7.66)％和(59.02±9.71)％]明显高于对照组[(48.94±12.66)％],差异具有统计学意义(F=11.128,P＜0.001);Ⅲ期和Ⅳ期患者的CD45RO+细胞百分率[分别为(47.19±8.30)％和(45.41±10.45)％]则明显低于对照组[(53.43±11.75)％],差异具有统计学意义(F=5.817,P=0.00083);Ⅲ期和Ⅳ期患者CD45RA+/CD45RO+的比值(分别为1.32 ±0.46和1.43±0.63)明显高于对照组(1.00±0.47),差异具有统计学意义(F=6.986,P=0.000185);Ⅰ+Ⅱ期患者CD4+ CD45 RO+细胞百分率[(31.37±6.39)％]明显高于对照组[(27.49±7.19)％],差异具有统计学意义(F=2.368,P=0.009);Ⅳ期患者CD4+ CD45RA+/CD4+ CD45RO+的比值(0.66±0.39)明显高于Ⅰ+Ⅱ期的患者(0.49±0.23),差异具有统计学意义(F=1.812,P=0.029);各组之间CD4+ CD45RA+细胞百分率无明显统计学差异(F=0.637,P=0.592).结论 随着临床分期的增加,结直肠癌患者外周血CD45RA+细胞逐渐增加而CD45RO+细胞逐渐减少,反映出结直肠癌患者随着肿瘤的进展其免疫功能逐渐抑制、逐渐降低的动态过程;CD4+ CD45RA+细胞和CD4+ CD45RO+细胞在反映结直肠癌患者机体免疫功能方面不如CD45RA+细胞和CD45RO+细胞敏感.     

Immune memory in CD4+ CD45RA+ T cells.

This study addresses the question of whether human peripheral CD4+ CD45RA+ T cells possess antigen-specific immune memory. CD4+ CD45RA+ T cells were isolated by a combination of positive and negative selection. Putative CD4+ CD45RA+ cells expressed CD45RA (98.9%) and contained < 0.1% CD4+ CD45RO+ and < 0.5% CD4+ CD45RA+ CD45RO+ cells. Putative CD45RO+ cells expressed CD45RO (90%) and contained 9% CD45RA+ CD45RO+ and < 0.1% CD4+ CD45RA+ cells. The responder frequency of Dermatophagoides pteronyssinus-stimulated CD4+ CD45RA+ and CD4+ CD45RO+ T cells was determined in two atopic donors and found to be 1:11,314 and 1:8031 for CD4+ CD45RA+ and 1:1463 and 1:1408 for CD4+ CD45RO+ T cells. The responder frequencies of CD4+ CD45RA+ and CD4+ CD45RO+ T cells from two non-atopic, but exposed, donors were 1:78031 and 1:176,903 for CD4+ CD45RA+ and 1:9136 and 1:13,136 for CD4+ CD45RO+ T cells. T cells specific for D. pteronyssinus were cloned at limiting dilution following 10 days of bulk culture with D. pteronyssinus antigen. Sixty-eight clones were obtained from CD4+ CD45RO+ and 24 from CD4+ CD45RA+ T cells. All clones were CD3+ CD4+ CD45RO+ and proliferated in response to D. pteronyssinus antigens. Of 40 clones tested, none responded to Tubercule bacillus purified protein derivative (PPD). No difference was seen in the pattern of interleukin-4 (IL-4) or interferon-gamma (IFN-gamma) producing clones derived from CD4+ CD45RA+ and CD4+ CD45RO+ precursors, although freshly isolated and polyclonally activated CD4+ CD45RA+ T cells produced 20-30-fold lower levels of IL-4 and IFN-gamma than their CD4+ CD45RO+ counterparts. Sixty per cent of the clones used the same pool of V beta genes. These data support the hypothesis that immune memory resides in CD4+ CD45RA+ as well as CD4+ CD45RO+ T cells during the chronic immune response to inhaled antigen.     

The role of cell maturation in the generation of phenotypic heterogeneity in B-cell chronic lymphocytic leukaemia.

B-chronic lymphocytic leukaemia (B-CLL) patients can be ranked along a progression of phenotypes characterized by a decreasing surface expression of CD20, CD21, CD22 and membrane immunoglobulin and a gradual replacement of the high molecular weight (MW) glycoproteins of the leucocyte-common antigen (LC) CD45RA by the lower MW components, including the CD45RO determinant. As CD20, CD21, CD22 and membrane immunoglobulin change during or after B-cell activation, and the CD45RA/CD45RO inversion is implicated in T-cell maturation, the possibility that the phenotypic differences are generated by a maturational diversity of the CLL clones has been investigated by testing the effects of TPA treatment of the leukaemic cells. TPA reduces the level of expression of CD20, CD21, mIg and CD45RA and increases CD45RO binding, thereby minimizing the phenotypic heterogeneity of the CLL clones and causing them to converge towards one end of the natural range. We propose that the phenotypic diversity in CLL is, at least in part, a consequence of maturational diversity where lymphocyte development is disrupted at different stages in different patients.