CD45RA在肝炎和肝癌患者中的表达变化及其意义

本研究旨在探讨CD45RA在肝炎和肝癌患者中的表达变化及其在发病机制中的意义。     

The role of CD45RO in antithymocyte globulin's stimulation of primitive haemopoietic cells

Summary. We have found that antithymocyte globulin (ATG), an equine antibody with proven efficacy in aplastic anaemia (AA), has a direct stimulatory effect on primitive haemopoietic cells from normal donors. This growth stimulation may be mediated via anti-CD45RO activity present in the ATG preparation. Addition of unabsorbed ATG enhanced colony growth at 21 d in the blast colony forming cell (Bl-CFC) assay. Prior absorption of ATG by incubation with the CD45RO⁺ MOLT-4 cell line resulted in the loss of enhancement. Absorption by MOLT-4 cells preincubated with anti-CD45RO mAb, UCHL-1, restored ATG's stimulatory effect. The Bl-CFC could also be stimulated to grow by the addition of UCHL-1 directly. Incubation of the primitive haemopoietic cells for 4 h with ATG was associated with a decline in the antigenic density of CD45RO, a tyrosine phosphatase. This down-regulation may upset the balance between growth factor-induced tyrosine kinase activation and tyrosine phosphate dephosphorylation resulting in increased growth of primitive cells. a possible factor in the sustained recovery of haemopoiesis seen in AA patients after ATG treatment.     

Hyposialated 185 kDa CD45RA+ molecules attain a high concentration in B lymphoma cells and in activated human B cells

Alternate splicing of exons of the CD45 molecule generates multiple isoforms differing in their molecular weights (MWs). In B-lymphocytes the CD45RA isoform was previously shown to be expressed on glycoproteins with MWs of 220 and 205 kDa, while the CD45RO isoform was expressed on glycoproteins with MW of 180 kDa. The present study demonstrated that B cell lymphomas and activated B-cells contain CD45 molecules with a MW of 185 kDa that express the CD45RA and CD45RC specificities but neither the CD45RB nor the CD45RO specificities. 185 kDa CD45RA+ molecules were detected in B cell lymphoma B lines, in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines, and in tonsillar B cells, but not in normal, unstimulated peripheral blood B cells. These molecules were not detected in neoplastic and normal T cells. CD45RA+ 185 kDa molecules were present in B cells from three non-Hodgkin's patients in leukemic phase were not detected in B lymphocytes of seven of nine CLL patients tested. Trypsin treatment eliminated only 220 kDa CD45RA+ molecules but not 185 kDa CD45RA+ molecules, indicating that the 185 kDa CD45RA+ molecules are not expressed on the cell surface. Pulse-chase experiments, and studies on the effects of tunicamycin, neuraminidase and O-glycosidase, indicated that the 185 kDa molecules are partially glycosylated CD45RABC molecules that constitute precursors of the 220 kDa molecules. The high concentration of 185 kDa CD45RA+ molecules in B lymphoma cells and in activated B cells seems to reflect a high turnover of CD45RA+ molecules characteristic for these cells.     

CD45RA expression by CD4 T lymphocytes in tumors invaded by B-cell non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD).

Little is known about the role of tumor infiltrating T lymphocytes (TIL-T) in the pathogenesis of malignant diseases and collaboration between normal and malignant cells has not yet been proved. In the present work, we have investigated whether immune T lymphocytes exist in tumors invaded by B-cell non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD). Therefore, we have studied the reactivity of the CD45RA monoclonal antibody, which discriminates between naive and memory CD4 T lymphocytes. Our results showed far lower percentages of CD4+ CD45RA+ in malignant lymphoma (30.3 +/- 15.0% in B-cell NHL, and 37.4 +/- 18.6% in HD) than in reactive hyperplasia (54.7 +/- 13.2%), leading to the conclusion of an accumulation of immune cells in tumor microenvironment. A further heterogeneity in the relative proportion of naive and memory TIL-T was also observed within lymphoma (range: 11 to 68% in B-cell NHL, 5 to 69% in HD). In B-cell NHL, it was related to histological features, as documented by the Kiel classification (P = .028), and to a stronger extent to cytological characteristics analysed with the Grenoble classification (P less than .0001): class 1 NHL, which are essentially indolent NHL displayed lower naive cells (22.2 +/- 7.4%) than class 3 NHL, which are more aggressive (40.1 +/- 16.1%). Among the monoclonal antibodies (mAb) defining the B-cell clone phenotype or activation state (CD19, CD20, CD21, CD22, CD23, CD24, CD5, CD10, CD11a, and Ki67), only CD23 (P = .0003) and Ki67 (P = .0007) revealed statistical association with the percentage of naive CD4 lymphocytes. No correlation could be demonstrated with the proportion of whole TIL-T, activated CD3 DR TIL-T, or CD4 subset.     

Clinical significance of CD45RO expression on peripheral blood mononuclear cells in HTLV-I-infected individuals

The phenotype of peripheral blood mononuclear cells (PBMC) was examined in 13 healthy volunteers, 26 HTLV-I carriers, and 58 ATL patients (22 smouldering, five chronic, 24 acute, and seven lymphoma type). The percentage of CD4⁺, CD25⁺, CD28⁺ and CD45RO⁺ cells in the PBMC of the chronic and acute type patients was significantly higher than that of the volunteers, whereas the percentage of CD8⁺ and CD45RA⁺ cells in these patients was significantly low. The histogram for CD45RO fluorescence intensity (FI) revealed two patterns: pattern A consisted of CD45RO⁺ cells with high FI (CD45RO^high) and intermediate FI (CD45RO^int). Pattern B consisted exclusively of CD45RO^high. Pattern A was evident in all volunteers. The percentage of subjects showing pattern B was increased in an order that reflected disease progression. In the patients with pattern A, the CD45RO^int cells were CD4⁺ and CD8⁻, and the FI of CD2, CD3, and Fas within the CD45RO^int cells appeared to be lower than that within the CD45RO^high cells. The acute type patients with pattern A had a significantly longer survival curve than that of these patients with pattern B. These results suggest that the presence of CD45RO^int cells may be related to protection against disease progression in HTLV-I-infected individuals.     

Galectin-1 supports the survival of CD45RA(-) primary myeloma cells in vitro

The survival and proliferation of human myeloma cells are considered to be heavily dependent on the microenvironment of bone marrow (BM). This study confirmed that galectin-1 (Gal-1) and SDF-1α were produced by bone marrow mononuclear cells of myeloma patients. The addition of Gal-1 and SDF-1α to a serum-free synthetic medium, maintained the viability of primary myeloma cells for 2 weeks similar to that before culture. While Gal-1 reduced the viable cell number in CD45RA(+) B cell lines, it maintained the viability of CD45(−) U266 and CD45RA(−)RO(+) ILKM3 myeloma cell lines in the synthetic medium. This was confirmed with the transfection of the PTPRC (CD45) RA, -RB, or -RO gene into CD45(−) U266 cells. The combination of Gal-1 and SDF-1α significantly induced phosphorylation of Akt and IkB, while the phosphorylation of ERK1/2 was significantly reduced in CD45RA(+) U266 and Raji cells but not CD45(−) or CD45RA(−) U266 cells. Furthermore, we confirmed that Gal-1 bound to CD45RA in CD45RA(+) Raji cells, and also physically interacted with β1-integrin by immunoprecipitation followed by Western blotting and confocal microscopy. The results suggest that Gal-1 has two different actions depending on its binding partner, and supports the survival of CD45RA(−) myeloma cells.     

Expression of CD45RA (naive) and CD45RO (memory) antigens in T-acute lymphoblastic leukaemia

Summary. We have determined the distribution of CD45RO (memory) and CD45RA (naive) antigens in the bone marrow blasts from 25 patients with T-acute lymphoblastic leukaemia (T-ALL). Four groups of patients were identified on the basis of reactivity with specific antibodies by flow cytometric analysis: (a) CD45KA-/CD45K0+ (16 patients): four CD4 - /CD8 +, seven CD4 +/CD8 + and five CD4 - /CU8 -: (b) CD45KA +/CD45RO- (three patients): three CD4-/ CD8-; (c) five CD45RA-/C1>45RO-: one CD4 +/CD8-: one CD4-/CU8 +: three CD4 +/CD8 +: (d) CD45RA +/ CD45K0+ (one case): CD4+/CD8 -. There was no correlation between the expression of the naive and the memory phenotypes and the presence of CD4, CD8 or any other antigen except the CD10 antigen which was expressed by all CD45RA-/CD45RO- patients. The predominance of the CD45KA-/CD45RO+ phenotype (65%) and the low incidence of the hybrid phenotype CD45KA +/CD45KO+ (5%) in T-ALL. differs from the results reported by others for chronic or prolymphocytic T-cell leukaemias, in which the simultaneous expression of these maturational antigens was detected in approximately half of the cases.     

Expression of the leucocyte common antigen (LCA,CD45) isoforms RA and RO in acute haematological malignancies: possible relevance in the definition of new overlap points between normal and leukaemic haemopoiesis

Summary. The membrane expression of CD45RA and CD45RO on fresh leukaemic cells taken from 529 cases of acute haemopoietic malignancies, including 117 B-origin acute lymphoblastic leukaemia (B-origin ALL), 3 7 T-origin acute lymphoblastic leukaemia (T-origin ALL), 297 de novo acute myeloid leukaemia (AML), 42 refractory anaemia with excess of blasts in transformation (RAEB-T) and 36 myeloid blastic phase of chronic myelogenous leukaemia (CML-BP-my), was analysed. B-origin ALLs were characterized by the lack of the RO isoform along with the consistent presence of RA. Conversely, a differential expression of the two isoforms was detected in different subsets of T-origin ALL, in that T-stem cell leukaemias (T-SCL: CD7⁺, CD4^?, CD8^?, CD1^?) preferentially expressed CD45RA whereas conventional T-acute lymphoblastic leukaemias (T-ALL: CD7⁺, CD4⁺ and/or CD8⁺ and/or CD1+) were consistently marked by CD45RO. Within myeloid malignancies, most of AMLs displayed CD45RA, while a substantial group of CML-BP-my preferentially exhibited CD45RO. As a general rule, a reciprocal exclusion of the two isoforms was observed in AML as well as in ALL. Nevertheless, a frequent coexpression of CD45RA and CD45RO was observed in CD14⁺ AML. In vitro treatment with all-trans retinoic acid (ATRA) was able to promote a switch from CD45RA to CD45RO expression in 2 7 de novo AML, independently from morphological subtyping. To our knowledge, this is the first report on CD45 isoform expression in a large series of patients with acute leukaemia. The knowledge of the differential expression of CD45RA and CD45RO can ameliorate our classificative approach to haematological malignancies, as well as disclose new multiple overlap points between normal and leukaemic cell differentiation.     

Relationship between CD45 antigen expression and putative stages of differentiation in B-cell malignancies.

The cell-surface antigen CD45 is a complex family of high-molecular-weight glycoproteins expressed on all lymphohematopoietic cells, but not in the same molecular isoform. This antigen complex is known to exhibit protein tyrosine phosphatase (PTPase) activity and appears to have a role in regulation of cell differentiation. In that CD45 expression parallels stages of differentiation in normal bone marrow B cells, it was of interest to evaluate this process in malignant B cells. Monoclonal antibodies (MoAbs) were used to investigate the quantitative expression of CD45 and CD45RA on the B cells of lymphoid leukemias. Employing standardized flow cytometric methods, it was found that the fluorescence intensity (FI) of immunostained malignant B cells, as a reflection of the antigen content, demonstrated correlations with the putative stage of cell differentiation for malignancies at the earlier stages, but at the later stages, a progressive loss of CD45 was observed. Since this antigen family has been found to display PTPase activity, further investigation of CD45 alterations in malignancies may provide insight into potential regulatory disturbances.     

B-lymphocytes in CLL and NHL differ in the mRNA splicing pattern of the CD45 molecule

In the present study the cell surface expression of CD45 isoforms on normal and neoplastic human B cells was correlated with splice products of the CD45 mRNA, using RT-PCR technology. In non-Hodgkin's lymphoma cells in the leukemic phase (NHL) the majority of the cells expressed a high level of CD45RA, while in CLL most of the cells expressed a low level. In the Raji and Daudi Burkitt B-cell lymphoma lines the main CD45 mRNA product was the largest, unspliced, full-length isoform (456) and the 56 splice product. Similar results were obtained with B-cell lymphoma cells isolated from the peripheral blood of patients with NHL in the leukemic phase. In EBV-transformed B-cell lines, the 456 and the 56 isoform of CD45 mRNA were predominant, but in addition a low level of the 5- and 0-exon splice products was detected. A strikingly different pattern was obtained with B-CLL cells. In CLL the level of the 456 and the 56 isoforms was low, while that of the 5- and 0-exon splice products was increased. Thus, in contrast to the heterogeneity in the expression of CD45RO in B-CLL, the majority of the cells contained the CD45 mRNA splice product coding for CD45RO. Analysis of splice products of the CD45 mRNA may serve as an additional tool to differentiate CLL from the leukemic phase of NHL.     

Low percentages of regulatory T cells in common variable immunodeficiency (CVID) patients with autoimmune diseases and its association with increased numbers of CD4+CD45RO+ T and CD21low B cells

BackgroundCommon variable immunodeficiency (CVID) is a heterogeneous group of primary antibody deficiencies defined by marked reductions in serum IgG, IgA and/or IgM levels and recurrent bacterial infections. Some patients are associated with defects in T cells and regulatory T cells (Tregs), resulting in recurrent viral infections and early-onset autoimmune disease.MethodsWe analyzed whether there is an association between Tregs cells (CD4+CD25+CD127^low and CD4+CD25+FoxP3+); memory T cells (CD4+CD45RO+); memory B cells (CD19+CD27-IgD-); and CD21^low B cells (CD19+CD38^lowCD21^low); as well as autoimmune manifestations in 36 patients with CVID (25 women and 11 men, mean age 24 years), all by flow cytometry.ResultsFourteen patients presented with autoimmune diseases (AI) (39%), including 11 with autoimmune thrombocytopenia (ITP) (31%); two with vitiligo (6%); one with systemic lupus erythematosus (LES) (3%); and one with multiple sclerosis (MS) (3%). CVID patients with AI had a reduced proportion of Tregs (both CD4+CD25+CD127^low and FoxP3+ cells) compared with healthy controls. CVID patients with AI had expanded CD21^low B cell populations compared with patients who did not have AI. A correlation between increased CD4+CD45RO T cell populations and reduced Tregs was also observed.ConclusionsOur results showed that 39% of patients with CVID had AI and reduced Tregs populations. Research in this area might provide noteworthy data to better understand immune dysfunction and dysregulation related to CVID.     

High CD95 expression of BAL lymphocytes predicts chronic course in patients with sarcoidosis

BACKGROUND AND OBJECTIVES: The prognosis of sarcoidosis is highly variable, with spontaneous remission in some patients. Apoptosis may be associated with spontaneous resolution of the granulomata. CD95 (Fas), an apoptotic molecule, and CD29 and CD45RO (T-cell memory markers) are expressed at higher levels on T lymphocytes from sarcoid patients compared with normal subjects. However, the prognostic significance of CD95, CD29 and CD45RO expression in sarcoidosis is not clear. It was hypothesized that expression of CD95 would correlate with spontaneous remission. METHODS: CD29, CD45, CD45RO and CD95 expression of BAL fluid and peripheral blood (PB) lymphocytes was studied with flow cytometry in 50 patients with sarcoidosis. Results of the 15 chronic patients and 21 patients who remitted spontaneously were compared. RESULTS: BAL CD95 (59 vs 8, P = 0.002), and PB CD95 (48 vs 18, P = 0.004) and PB CD45RO (50 vs 41, P = 0.003) expression was significantly higher in patients with chronic disease compared with those with spontaneous remission. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy for these markers were: BAL CD95 (cut-off: 42.5%) 73.3%, 85.7%, 78.6%, 81.8% and 80.6%; PB CD95 (cut-off: 25%) 86.7%, 66.7%, 65%, 87.5% and 75%; and PB CD45RO (cut-off: 44.5%) 80%, 61.9%, 60%, 81.3% and 69.4%, respectively. CONCLUSION: Levels of BAL and PB CD95 and PB CD45RO were unexpectedly elevated in patients with chronic disease and may be useful in predicting prognosis in patients with sarcoidosis. Further studies with more patients are necessary to confirm the prognostic role and cut-off value for these markers.     

Selective loss of peripheral blood CD45RO+ T lymphocytes correlates with increased levels of serum cytokines and endothelial cell-derived soluble cell adhesion molecules in patients with chronic idiopathic neutropenia of adults

 The present study was designed to investigate the hypothesis that selective loss of peripheral blood CD45RO⁺ T lymphocytes in patients with chronic idiopathic neutropenia of adults (CINA), previously reported from our laboratory, may be due to enhanced extravasation into the tissues. Serum levels of endothelial cell-derived soluble cell adhesion molecules (sELAM, sICAM and sVCAM), usually used as indicators of endothelial cell activation, were measured in 73 CINA patients and 32 healthy volunteers using a micro-ELISA method. We found that patients had markedly elevated concentrations of all three soluble cell adhesion molecules studied compared to the controls, and serum levels of sELAM, sICAM and, more importantly, sVCAM correlated inversely with the numbers of both CD4⁺/CD45RO⁺ and CD8⁺/CD45RO⁺ T cell subsets. Using a micro-ELISA method, we also measured serum levels of two endothelial cell activators, interleukin (IL)-1β and TNF-α, and found that CINA patients had significantly higher cytokine concentrations than control subjects. Serum levels of IL-1β and TNF-α correlated positively with the values of all three soluble cell adhesion molecules and inversely with the numbers of CD4⁺/CD45RO⁺ and CD8⁺/CD45RO⁺ T cell subsets. Moreover, we measured serum levels of the chemokine RANTES by a micro-ELISA technique and found that CINA patients also had elevated concentrations of the molecule compared to controls. Serum RANTES correlated positively with IL-1β, TNF-α, sICAM, sVCAM and sELAM and inversely with the numbers of both CD4⁺/CD45RO⁺ and CD8⁺/CD45RO⁺ T cell subsets. These findings strongly suggest that CINA patients have an activated endothelium to which CD45RA⁺ and CD45RO⁺ T cells tether and roll, but firm adhesion and transendothelial migration are restricted to CD45RO⁺ T cell subsets, as endothelial VCAM-1 interacts with the vascular leukocyte adhesion molecule-4 (VLA-4) constitutively expressed on CD45RO⁺ but not on CD45RA⁺ T cells. Subsequent subendothelial and tissue migration of CD45RO⁺ T cells may be facilitated by the chemokine RANTES, which acts mainly on CD45RO⁺ T cells. We concluded that selective loss of peripheral blood CD45RO⁺ T lymphocytes in CINA patients is probably due, at least in part, to enhanced extravasation of both CD4⁺/CD45RO⁺ and CD8⁺/CD45RO⁺ T cell subsets into the tissues. Received: February 18, 1998 / Accepted: June 10, 1998     

Selective T‐cell depletion targeting CD45RA reduces viremia and enhances early T‐cell recovery compared with CD3‐targeted T‐cell depletion

1 Background

T‐cell depletion (TCD) effectively reduces severe graft‐versus‐host disease in recipients of HLA‐mismatched allografts. However, TCD is associated with delayed immune recovery and increased infections. We hypothesized that specific depletion of CD45RA+ naive T cells, rather than broad depletion of CD3+ T cells, can preserve memory‐immunity in the allografts and confer protection against important viral infections in the early post‐transplant period.

2 Methods

Sixty‐seven patients who received TCD haploidentical donor transplantation for hematologic malignancy on 3 consecutive trials were analyzed.

3 Results

Patients receiving CD45RA‐depleted donor grafts had 2000‐fold more donor T cells infused, significantly higher T‐cell counts at Day +30 post transplant (550/μL vs 10/μL; P < .001), and higher T‐cell diversity by Vbeta spectratyping at Day +100 (P < .001). Importantly, these recipients experienced a significant reduction in both the incidence (P = .002) and duration (P = .02) of any viremia (cytomegalovirus, Epstein‐Barr virus, or adenovirus) in the first 6 months post transplant. Specifically, recipients of CD3‐depleted grafts were more likely to experience adenovirus viremia (27% vs 4%, P = .02).

4 Conclusion

CD45RA‐depletion provided a large number of donor memory T cells to the recipients and was associated with enhanced early T‐cell recovery and protection against viremia.     

CD4/CD45双色单平台法检测HIV感染者CD4~+ T淋巴细胞研究进展

CD4+T淋巴细胞计数是评价AIDS疾病进展和抗病毒治疗效果的重要指标。本文介绍了流式细胞仪CD4+T淋巴细胞计数方法的发展历史。将CD4/CD45双色单平台法的准确性、可靠性和经济性与其他方法进行了比较。表明该法简便、廉价且实用性强。同时介绍了当前适用于CD4/CD45双色单平台法的几款流式细胞仪的机型特点。     

Expression of CD8β and alteration of cell surface phenotype in adult T-cell leukaemia cells

Typical adult T-cell leukaemia (ATL) cells have a CD4⁺CD8⁻ cell surface phenotype, but atypical phenotypes such as CD4⁺CD8⁺ and CD4⁻CD8⁺ have also been reported. The CD8 molecule is composed of α and β chains and commonly used monoclonal antibodies against CD8 molecule detect only CD8α. Since it has been reported that CD8α can be induced in mature CD4⁺ T cells by cell activation, but not CD8β, we studied whether ATL cells which express CD8α may also express CD8β. We found some cases of CD8α⁺ ATL were also positive for CD8β. Furthermore, we experienced a case whose ATL cell surface phenotype changed from CD4⁺CD8α⁺CD8β⁺ to CD4⁻CD8α⁺CD8β⁺ and finally to CD4⁺CD8α⁻CD8β⁻. Southern blot analysis revealed that the monoclonal integration of human T lymphotropic virus type I (HTLV-I) was identical throughout the course of the study, indicating that a single clone had demonstrated the alterations. These data suggest that peripheral CD4⁺CD8⁺ ATL cells can express not only CD8α, but also CD8β and that a single ATL cell clone has the potential to change its surface phenotype in vivo as well as in vitro .     

猪带绦虫TSO45W-4BX与猪CD58分子在大肠埃希菌中的联合表达

目的以猪CD58为分子佐剂,将CD58基因与猪带绦虫疫苗候选抗原基因TSO45W-4BX联合表达,寻找新型抗猪囊尾蚴疫苗。方法分别以重组质粒pGEM-4B和pGEM-CD58为模板,PCR扩增猪带绦虫TSO45W-4BX基因和猪CD58基因,将TSO45W-4BX与酶切处理的pGEX-4T-1定向连接,转化大肠埃希菌JM109,重组质粒经鉴定正确后,在其下游酶切插入CD58基因,PCR扩增和测序证明阅读框正确后,用异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达,用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE))和蛋白质印迹法(Westernblotting)分析表达产物的免疫活性。结果pGEX-4BX和pGEX-4BX/CD58分别表达Mr41000和Mr69000的融合蛋白,pGEX-4BX表达产物主要以可溶性形式存在,而pGEX-4BX/CD58却以包涵体形式存在,但两者都能被囊尾蚴病患者血清识别。结论TSO45W-4BX与CD58基因联合表达,TSO45W-4BX仍具有免疫活性。     

Transitions in CD45 isoform expression indicate continuous differentiation of a monoclonal CD5+ CD11b+ B lineage in Waldenstrom's macroglobulinemia.

Waldenstrom's macroglobulinemia (WM) has been hypothesized to be a pleomorphic B-cell malignancy with persistent maturation towards plasma cells in all lymphoid tissue. This proposal is based on detection of a heterogeneous density of monoclonal Ig on peripheral blood B-cells in patients with WM. We now present data derived from 2- and 3-color immunofluorescence and flow cytometric analysis that strongly supports this hypothesis. Abnormally high numbers of B lineage cells, defined by expression of CD19, CD20, and CD24, were found among peripheral blood mononuclear cells (PBMC). These B-cells are monoclonal as defined by light chain expression and by the existence of rearranged Ig genes (Southern blot analysis), although they exhibit heterogeneity in the density of surface light chain. Unlike normal PBMC B-cells, the monoclonal B-cells bear CD5 and CD10 (CALLA), express adhesion and adhesion-related molecules (CD11b, CD9), and appear to be actively differentiating during the course of the disease, based on the pattern of CD45 isoform expression. At any given point in time, the population of monoclonal B-cells is heterogeneous in differentiation stage based on transitions in the expression of CD45 isoforms from expression of CD45RA, the high molecular mass isoforms of CD45, to the low molecular mass isoform CD45R0 which appears only on very late stage B-cells and early plasma cells. For one patient, analysis of CD45 isoform expression over 2 years showed that the monoclonal B-cell population as a whole progressed towards terminal differentiation as defined by loss of CD45RA and acquisition of CD45R0. This indicates a continuously differentiating lineage of an unusual B-cell phenotype, and/or malignant transformation of a distinct lineage of B-cells in WM.     

Fas/Fas Ligand Expression and Characteristics of Primed CD45RO+ T Cells in the Inflamed Mucosa of Ulcerative Colitis

Background: Chronic immune activation in the colon is characteristic of ulcerative colitis (UC). Fas/Fas ligand (FasL) system is a mechanism responsible for activation-induced cell death (AICD), which maintains homeostasis within the immune system. Thus, Fas/FasL expression on activated colonic T cells of UC patients, as well as the susceptibility of such T cells to AICD was investigated in order to determine the role of activated colonic T cells in the long lasting inflammation in UC. Methods: Fas, FasL, and CD45RO expression on peripheral blood and colonic T cells of UC patients were assayed by flow cytometry. Apoptosis of colonic T cells induced by anti Fas antibody was assessed using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Results: The majority of colonic T cells expressed both CD45RO and Fas in the colonic mucosa, a situation that was quite different from that in the peripheral blood. The number of CD45RO⁺CD8⁺ and Fas⁺CD8⁺ T cells was significantly lower in UC patients than the controls, unlike the number of Fas⁺CD4⁺ T cells. In contrast, the number of both CD45RO⁺CD4⁺ and CD45RO⁺CD8⁺ T cells in UC mucosa expressing FasL was significantly higher than in the controls. While Fas mediated apoptosis of CD45RO⁺CD8⁺ T cells was higher in UC patients than the controls, the number of apoptotic CD45RO⁺CD4⁺ T cells from UC mucosa was not. Conclusions: In UC patients, CD45RO⁺CD4⁺ T cells are less sensitive to apoptotic signals mediated by Fas. These phenomena may contribute to the pathogenesis of UC.     

Long-term decrease of CD4+CD45RA+ T cells and impaired primary immune response after post-traumatic splenectomy

Congenital or acquired absence of the spleen and functional hyposplenism are associated with abnormalities of host defence such as an increased susceptibility to infection with encapsulated bacteria. The effects of the lack of the spleen on cell-mediated immunity are largely unknown. In the present study we have investigated peripheral blood lymphocyte subpopulations in healthy adults who had undergone splenectomy because of severe abdominal trauma > 4 years before the study. The results show a significant reduction in the percentage of CD4+ T cells due to a selective and long-term decrease in the percentage of CD4+CD45RA+ lymphocytes, the CD4+ T-cell subset mainly involved in primary immune responses to newly encountered antigens. Levels of the reciprocal CD45RO+CD4+ T-cell subset were comparable between splenectomized and control individuals, as were lymphoproliferative responses and IFN-gamma production to recall antigens. Decreased levels of CD4+CD45RA+ cells were accompanied by an impairment in primary immune responsiveness, as assessed by investigating T-cell proliferation to stimulation with keyhole limpet haemocyanin and by measuring antibody responses following primary immunization with a clinically relevant T-dependent antigen, hepatitis A vaccine, in vivo. These findings suggest a possible role of the spleen in the generation, maintenance and/or differentiation of naive, unprimed T cells or their precursors, which might have a possible functional relevance for primary immune responses following splenectomy.