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Minor Subset (minor + subset)
Selected AbstractsOverexpression of CD49f in precursor B-cell acute lymphoblastic leukemia: Potential usefulness in minimal residual disease detectionCYTOMETRY, Issue 2 2009Joseph A. DiGiuseppe Abstract Background: The persistence of minimal residual disease (MRD) following therapy is an established prognostic factor in precursor B-cell acute lymphoblastic leukemia (pB-ALL). Detection of MRD in pB-ALL by flow cytometric immunophenotyping requires demonstration of abnormal antigen expression in leukemic B-cell precursors relative to that of normal B-cell precursors. The gene encoding CD49f (integrin ,-6) is one of several whose overexpression in pB-ALL at diagnosis has been associated with the subsequent detection of MRD. However, whether CD49f might be a useful reagent in the immunophenotypic detection of MRD in pB-ALL has not been evaluated. Methods: We evaluated CD49f expression by 4-color flow cytometry in normal B-cell precursors, and in a series of cases of pB-ALL, both at diagnosis and at intervals following the initiation of therapy. Results: In 10 control marrow samples, CD49f was undetectable or extremely dim in all but a minor subset of normal CD19+ B-lineage cells, whereas in 11 of 15 cases (73%) of pB-ALL, CD49f was moderate or bright at diagnosis, and persisted or became brighter after initiation of therapy. MRD detected using CD49f corresponded precisely with that obtained using a standard panel of antibodies, and permitted the detection of leukemic populations comprising as little as 0.02% of cells. Of the four pB-ALL cases in which CD49f was undetectable or dim at diagnosis, MRD was detected in two; in one of these, CD49f expression was substantially increased in the leukemic cells that persisted following initiation of therapy. Conclusions: CD49f is commonly overexpressed in p-B-ALL, and represents a potentially useful marker for the immunophenotypic detection of MRD. © 2008 Clinical Cytometry Society How to cite this article: DiGiuseppe JA, Fuller SG, Borowitz MJ. Overexpression of CD49f in precursor B-cell acute lymphoblastic leukemia: potential usefulness in minimal residual disease detection. Cytometry Part B 2008. [source] Cells meeting our immunophenotypic criteria of endothelial cells are large plateletsCYTOMETRY, Issue 2 2007Michiel H. Strijbos Abstract Background Circulating endothelial cells (CEC) are shed from damaged vasculature, making them a rational choice to serve as surrogate marker for vascular damage. Currently, various techniques and CEC definitions are in use, and their standardization and validation is needed. A flow cytometric single platform assay defining CEC as forward light scatter (FSC)low-to-intermedate, sideward light scatter (SSC)low, CD45,, CD31++ and CD146+ is a promising approach to enumerate CEC because of its simplicity (Mancuso et al., Blood 2001;97:3658,3661). Here, we set out to confirm the endothelial nature of these cells. Methods We isolated cells with a FSClow-to-intermediate, SSClow, CD31++, CD45dim immunophenotype (termed "cells meeting our immunophenotypic criteria for endothelial cells" [CMOIC]) from healthy donors to study the expression of endothelium-associated markers using several techniques. Special attention was paid to reagents identifying the endothelial cell-specific marker CD146. We compared antigen expression patterns of CMOIC with those of the HUVEC endothelial cell line and lymphocytes. Electron microscopy was used to detect the presence of endothelial cell-specific Weibel,Palade bodies in the sorted cells. Results CD146 expression was negative on CMOIC for all tested CD146 mAbs, but positive on HUVEC cells and a minor subset of T lymphocytes. Using flow cytometry, we found no expression of any endothelium-associated marker except for CD31 and CD34. HUVEC cells were positive for all endothelial markers except for CD34. Evaluation of CMOIC morphology showed a homogenous population of cells with a highly irregular nucleus-like structure and positive endothelial immunohistochemistry. CMOIC contained neither nuclei nor DNA. Electron microscopy revealed the absence of a nucleus, the absence of endothelial specific Weibel,Palade bodies, and revealed CMOIC to be large platelets. Conclusion The vast majority of cells with the immunophenotype FSClow-to-intermediate, SSClow, CD45,, CD31++ do not express CD146 and are large platelets rather than endothelial cells. © 2007 Clinical Cytometry Society. [source] Current management of adult idiopathic thrombocytopenic purpura in practice: a cohort study of 201 patients from a single center,INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2004J. Zimmer Summary To define usefulness and response to therapy and outcome in adults with idiopathic thrombocytopenic purpura (ITP) in clinical practice. We retrospectively reviewed a cohort of 201 consecutive patients with ITP, diagnosed between 1985 and 1994. In particular, we analyzed the therapies used, their response rates, prognostic indicators of response and outcome. In 62 patients, with minor bleeding episodes and a mean (±SD) platelet count of 88 ± 23 × 109/l, no treatment was used and chronic ITP was diagnosed in 59%. A total of 139 patients, with bleeding episodes in 71.2% cases and a mean platelet count of 20 ± 13 × 109/l, received at least one treatment. Three patients died (1.5% of the series). Corticosteroids were used in 118 patients, with an initial response rate of 82.2% and a long-term complete response (CR) of only 22.9%. Intravenous immunoglobulin was used in 26 patients, with an initial transient response in more than 60%. A splenectomy was performed in 55 patients, with an initial response rate of 92.5% and a long-term CR in 60%. Young age and prior response to corticosteroids were significant predictors of a durable response to splenectomy. Danazol was given in 37 patients, with a favorable response in 73% of cases. Our results illustrate the guidelines of the American Society of Hematology. Patients with moderate thrombocytopenia do not require treatment. In severe cases, splenectomy is the only treatment giving durable cures in a significant proportion of patients. Despite frequent chronicity, ITP is life-threatening only in a minor subset of patients. [source] Despite large-scale T cell activation, only a minor subset of T cells responding in vitro to Actinobacillus actinomycetemcomitans differentiate into effector T cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 3 2000Homayoun H. Zadeh Recent studies in our laboratory have demonstrated that Actinobacillus actinomycetemcomitans has a potent T cell stimulatory effect, activating more than half of all T cells. However, since the fate of these activated T cells was not known, the present study sought to determine whether all of these T cells differentiate into effector cells. To that end, the intracellular expression of T cell cytokines (IL-2, IFN-,, IL-4 and IL-10) in response to A. actinomycetemcomitans was determined by flow cytometry. Results demonstrated a time-dependent increase in the expression of the cytokines, most reaching peak levels at 24,48 h. At 48 h, the proportion of T cells expressing each of the cytokines were as follows: IL-2 (1.7%±0.3), IFN-,(1.8%±0.5), IL-4 (1.0%±0.2) and IL-10 (1.5%±0.5). These data indicated that only 2,5% of all T cells stimulated with A. actinomycetemcomitans expressed any T cell cytokines. The finding of large-scale T cell activation in the absence of cytokine expression suggests that the activation of T cells in response to A. actinomycetemcomitans is incomplete. To investigate this phenomenon, peripheral blood mononuclear cells (PBMC) were cultured with A. actinomycetemcomitans for 24 h followed by sorting of the activated (CD69+) cells by immunomagnetic separation and restimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. Results demonstrated that nearly 90% of the T cells were unresponsive to further restimulation. A possible explanation for this unresponsiveness is the induction of clonal anergy among the responding T cells. To determine possible preferential effects of the stimulation on specific cytokines, the expression of each cytokine among T cells responding to A. actinomycetemcomitans was compared to the maximum levels achieved by PMA+ionomycin stimulation. Results showed that number of IL-2+ and IFN-,+ T cells observed in response to A. actinomycetemcomitans were between 2% and 7% of those seen in response to PMA+ionomycin. Conversely, the proportions of T cells expressing IL-4 or IL-10 were between 35% and 90% of those following stimulation with PMA+ionomycin. Hence, A. actinomycetemcomitans appears to more preferentially induce T cells [source] Association of interferon regulatory factor 5 haplotypes, similar to that found in systemic lupus erythematosus, in a large subgroup of patients with rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 5 2008Rebeca Dieguez-Gonzalez Objective Previous studies have shown either a lack of effect of IRF5 polymorphisms or an association of the IRF5 gene in only a minor subset of rheumatoid arthritis (RA) patients in whom anti,citrullinated protein antibodies (ACPAs) are absent. The present study was undertaken to investigate the role of genetic variation in IRF5 in susceptibility to RA. Methods Nine IRF5 single-nucleotide polymorphisms (SNPs) were studied in 1,338 patients with RA and 1,342 control subjects in analyses of exploratory and replication sample collections, with stratification according to sex and by the presence or absence of ACPAs, rheumatoid factor, the shared epitope, the 620W PTPN22 allele, and erosions. A meta-analysis that included results from previous studies was also carried out. Results Our findings together with those from previous studies, in a total of 4,620 RA patients and 3,741 controls, showed a significant association of the rs2004640 IRF5 SNP in RA patients as a whole (odds ratio [OR] 0.88, 95% confidence interval [95% CI] 0.83,0.94; P = 6.5 × 10,5 versus controls). This association was stronger in ACPA, patients, but was also present in ACPA+ patients (from 3 sample collections). Further analysis of our exploratory sample collection showed that only patients in the ACPA+ and SE, group lacked an association with IRF5 SNPs. All of the remaining RA patients (ACPA, or SE+) showed a strong association with IRF5 SNPs, which followed a complex pattern of opposing effects mediated by independent haplotypes. The susceptibility haplotype showed an OR of 1.8 (95% CI 1.4,2.3; P = 1.2 × 10,6 versus controls), whereas the protective haplotype showed an OR of 0.76 (95% CI 0.6,0.98; P = 0.046 versus controls). Conclusion IRF5 polymorphisms seem to influence RA susceptibility in a large subgroup of patients, following a pattern of association very similar to that described in patients with systemic lupus erythematosus. [source] TH1/TH2,3 Imbalance due to Cytokine-Producing NK, ,, T and NK-,, T Cells in Murine Pregnancy Decidua in Success or Failure of PregnancyAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 5 2001DAVID A. CLARK PROBLEM: Recurrent spontaneous abortion in DBA/2-mated CBA/J mice has been attributed to the production of Th1 cytokines (tumor necrosis factor [TNF]-, and interferon [IFN]-,) by asialoGM1+ natural killer (NK) cells and V,1.1,6.3+ T cells that infiltrate decidua by day 6.5, during the peri-implantation period. Abortions can be prevented by a second population of V,1.1,6.3 cells, which infiltrate on day 8.5 of gestation, and produce the Th2 cytokine interleukin (IL)-10 and Th3 cytokine transforming growth factor (TGF)-,2. In low abortion rate immunocompetent mice, most of the TGF-,2 is derived from ,, T cells. However, TGF-,2-producing cells are present in the decidua of pregnant severe combined immune deficient (SCID) mice, which lack ,, T cells. METHODS: The cells in day 13.5 decidua of CBA×DBA/2 matings and SCID×SCID matings were identified using flow cytometry and combined surface staining for ,, and/or asialoGM1, and intracellular cytokine staining for TNF-,, IFN-,, and TGF-,2,3. RESULTS: TGF-,2 and TNF-, were found in asialoGM1+ NK cells in SCID mouse decidua. In CBA×DBA/2 mated mice, two major and one minor subsets of cytokine-positive cells were identified: -,,-only T cells, double positive asialoGM1+,,+ (NK-,, T) cells, and a small number of asialoGM1+,,, NK-only cells. The NK-only and NK-,, T subsets showed a greater Th1/Th2,3 pattern of intracellular staining compared with the ,,-only subset. In the CBA×DBA/2 and SCID×SCID systems, Th1/Th2,3 ratios could not predict actual observed abortion rates but did correlate with susceptibility to abortions (if exposed to an additional stimulus such as stress). The known effect of in vivo administration of anti-asialoGM1 antibody on abortion rates within groups of mice exposed to such stresses could also be predicted. CONCLUSION: ,,+ cells in decidua (e.g. V,1+ cells which can recognize trophoblasts) differ based on the presence or absence of the NK marker-asialo-GM1. NK-,, T cells may be quite important in the Th1 response in early pregnancy that predisposes to abortions in CBA×DBA/2 matings, whereas ,, T-only cells appear to be protective. In pregnant SCID mice, the TNF-,+/TGF-,2+ NK population is greatly expanded. An activating stimulus (such as stress or endotoxin) appears to be as important in triggering abortions, as is the Th1/Th2,3 ratio at the feto,maternal interface. [source] | ||||||||||