Stefan Jacobsson

T-cell-mediated cytotoxicity toward platelets in chronic idiopathic thrombocytopenic purpura.

Chronic idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder that is characterized by increased platelet destruction and is believed to be autoantibody mediated. In this study, CD3+ T cells from ITP patients had increased expression of genes involved in cell-mediated cytotoxicity. In addition, cytotoxic cell-mediated lysis of autologous platelets was shown in active ITP. Our data suggest that T-cell-mediated cytotoxicity is an alternative mechanism for platelet destruction in ITP.

Recruitment of T cells into bone marrow of ITP patients possibly due to elevated expression of VLA-4 and CX3CR1

In idiopathic thrombocytopenic purpura (ITP), platelets are destroyed in the spleen, liver, and bone marrow (BM) by autoantibodies and cytotoxic T cells. In a DNA microarray screen of peripheral blood T cells, we found that VLA-4, CX3CR1, and CXCR4, involved in T-cell homing, had increased expression in ITP patients compared with controls. However, we only found increased protein expression of VLA-4 on T cells from peripheral blood by flow cytometry. To address a possible recruitment of T cells into the organs involved in platelet destruction, we analyzed T cells in BM. In BM, T-cell surface expression of VLA-4 and CX3CR1 was increased in ITP patients compared with controls. Furthermore, the number of CD3(+) T cells in BM, but not in blood, was increased in ITP patients compared with controls. This finding was confirmed by immunohistochemistry of BM biopsies. The number of regulatory T cells (CD4(+)/CD25(bright)) was decreased in the BM of ITP patients, whereas Fas expression was increased. In conclusion, ITP is associated with accumulation and activation of T cells in the BM. Recruitment of T cells into the target organ (eg, BM) is plausible and may be facilitated through increased VLA-4 and CX3CR1 expression. These molecules might serve as new treatment targets in ITP.

A transforming growth factor-β1-mediated bystander immune suppression could be associated with remission of chronic idiopathic thrombocytopenic purpura

Abstract Bystander immune suppression has been demonstrated in experimental models of oral immune tolerance induction. This phenomenon is associated with expression of transforming growth factor (TGF)-β1 and T-helper cell (Th) 2 cytokines. We have studied serum levels of Th cytokines and B- and T-lymphocyte subsets in chronic idiopathic thrombocytopenic purpura (ITP), a disorder in which the production of platelet autoantibodies might be caused by a cytokine network dysregulation. Forty-six patients with ITP were separated into three groups depending on the platelet count (pltc): (1) <50×109/l, (2) 50–150×109/l and (3) >150×109/l. We found significantly elevated plasma levels of the Th3 cytokine TGF-β1 in patients with pltc >150×109/l (23.5±2.8 ng/ml), compared with patients with pltc <50×109/l (2.3±0.6 ng/ml;P<0.0001), patients with pltc 50–150×109/l (7.2±1.7 ng/ml;P<0.0001) and healthy volunteers (9.8±1.3 ng/ml;P<0.01). The serum levels of the Th1 cytokines interleukin (IL)-2 and interferon (IFN)-γ were below the detection limits of the assays. Likewise, the Th2 cytokine IL-4 was not detectable or was very low both in patients and controls. The serum levels of IL-10, a Th2 cytokine, were within the assay range and patients with pltc <50×109/l had significantly lower levels (0.6±0.1 pg/ml) than both patients with pltc 50–150×109/l (1.8±0.1 pg/ml;P<0.005) and healthy volunteers (1.4±0.1 pg/ml;P<0.005). Furthermore, patients with pltc <50×109/l and splenectomised patients had significantly higher levels of CD4+CD25+ activated T cells [26.2±14.8% (P<0.05) and 26.7±11.9% (P<0.005), respectively] than healthy controls (16.5±4.0%). Also, the number of natural killer (NK) cells among patients with pltc >150×109/l were significantly elevated (26.6±16.0%;P<0.05) compared with controls (17.4±7.6%). In conclusion, our data corroborate previous findings of elevated numbers of activated T cells in chronic ITP patients with active disease, but neither a clear-cut Th1 nor a Th2 serum cytokine profile could be established. However, ITP in remission was associated with elevated TGF-β1, which might be a part of a bystander immune suppression. We propose that the effect of possible expression of TGF-β1 by oral immune tolerance induction deserves to be explored in ITP patients with an active disease.

Disturbed apoptosis of T-cells in patients with active idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is an organ specific autoimmune disorder in which T-lymphocyte abnormalities have pathogenetic importance. In a DNA microarray screen of CD3+ T-lymphocytes from ITP patients and healthy controls we found an altered expression of genes associated with apoptosis, e.g. A20, caspase-8 and Bax. This together with our previous findings of increased gene expression of Fas, interferon-g and IL-2 receptor beta (IL2RB) indicated an altered activation induced cell death (AICD) of T-cells in ITP. Using a proliferation assay we found that CD3+ lymphocytes from ITP patients were significantly more resistant to dexamethasone induced suppression compared to normal lymphocytes. We also found that cultured CD3+ lymphocytes from ITP patients in remission were more susceptible to apoptosis both in the presence and absence of dexamethasone compared to cells from patient with active ITP and healthy controls, as indicated by increased staining of AnnexinV binding. Our findings suggest that apoptotic resistance of activated T-lymphocytes in patients with active ITP may lead to defective clearance of autoreactive T-lymphocytes through AICD, which might cause a continued immune destruction of platelets. Conversely, a loss of resistance to AICD in ITP patients in remission might be an important mechanism for the achievement of remission.

Newly diagnosed bladder cancer: The relationship of initial symptoms, degree of microhematuria and tumor marker status

PURPOSE We recorded initial symptoms and evaluated the frequency and intensity of hematuria in patients with newly diagnosed bladder cancer. We also evaluated and compared the sensitivity of bladder wash cytology, NMP22 (Matritech, Newton, Massachusetts), BTA Stat (Bion Diagnostic Sciences, Redmond, Washington) and UBC antigen (IDL Biotech, Sollentona, Sweden) with hematuria dipsticks and flow cytometry for determining the size of erythrocytes in urine. MATERIALS AND METHODS Urine samples were collected from 92 patients with newly diagnosed bladder cancer, 64 with idiopathic microhematuria and 42 with nephritis. Urine was analyzed for NMP22, BTA Stat, UBC and erythrocytes size using flow cytometry. Bladder wash cytology was done at cystoscopy. Urine was analyzed for microhematuria with hematuria dipsticks at home for 7 consecutive days immediately before the operation and in the hospital on the day of surgery. RESULTS Sensitivity was 75% for NMP22, 78% for BTA Stat, 64% for UBC and 61% for flow cytometry at 73% specificity. Cytology had 42% sensitivity at 97% specificity. Tumor size, grade and stage had a statistically significant influence on NMP22, BTA Stat, UBC and cytology. Of the patients 75% had microhematuria on the day of the operation and 75% had hematuria at least 1 of 7 days when tested at home the last week before transurethral bladder resection. The 70% of all patients with macroscopic hematuria as the initial symptom did not seem to differ from those without the condition in tumor size, grade, stage or tumor marker levels. CONCLUSIONS Flow cytometry was not well enough able to distinguish patients with bladder cancer from controls. The sensitivity of all tested markers, including hematuria dipsticks, was high for large and high grade, high stage tumors. Further studies are needed to evaluate whether a marker could be used to determine priority among patients referred due to microhematuria.

Evidence for a light chain restriction of glycoprotein Ib/IX and IIb/IIIa reactive antibodies in chronic idiopathic thrombocytopenic purpura (ITP)

To address the assumption of clonally restricted antibodies in immune thrombocytopenias we studied sera from 19 patients with chronic ITP known to possess antibodies reactive with glycoprotein (GP) Ib/IX and/or GPIIb/IIIa. These sera were re‐analysed using the standard monoclonal antibody immobilization of platelet antigens (MAIPA) assay and 16 patients exhibited IgG antibodies reactive with GPIIb/IIIa; seven patients showed also a reactivity with GPIb/IX. Employing a light‐chain‐specific MAIPA assay, 75% (12/16) of these sera displayed GPHb/ Ilia‐specific antibodies that were light chain restricted; only 13% (2/16) of the GPIIb/IHa reactive sera showed a mixed kappa and lambda phenotype. A light‐chain‐restricted phenotype was also seen for the GPIb/IX reactive antibodies. To further substantiate these findings, the MAIPA assay was modified in order to avoid interference from human anti‐mouse antibodies. A high frequency of light‐chain restricted platelet antibodies was also found using the modified MAIPA technique. These results support the hypothesis of a clonal B‐cell expansion in immune thrombocytopenias, producing antibodies with a restricted idiotype repertoire and reacting with a limited number of epitopes.

Detection of platelet antibodies in chronic idiopathic thrombocytopenic purpura (ITP). A comparative study using flow cytometry, a whole platelet ELISA, and an antigen capture ELISA

Abstract: Chronic idiopathic thrombocytopenic purpura (ITP) is a consequence of rapid platelet destruction caused by circulating platelet antibodies. In this study we compared three methods for detecting serum platelet antibodies in a population of 65 patients with chronic ITP. In two of the techniques intact platelets were used as the antibody target, i.e. the whole platelet ELISA and the flow cytometric assay; in the third an antigen‐specific modified antigen capture ELISA (MACE) was employed. By using the whole platelet ELISA and the flow cytometric assay 35% and 45% of the patients, respectively, displayed an antiplatelet antibody. In most cases (26 of 29 patients) IgG was the predominant antiplatelet immunoglobulin. As analysed using the MACE‐technique glycoprotein (GP) Ib/IX‐specific antibodies occurred with the same frequency as antibodies specific for GPIIb/IIIa. Moreover, there was a poor correlation between the MACE results on the one hand and results from the intact platelet‐based techniques on the other, i.e. several patients were positive in one assay whereas they were negative in the other. We conclude that all three techniques have their merits and demerits; it appears reasonable that they should be used together in the evaluation of the autoimmune process of chronic ITP.

Minimal residual disease assessment in childhood acute lymphoblastic leukaemia: a Swedish multi-centre study comparing real-time polymerase chain reaction and multicolour flow cytometry.

Minimal residual disease (MRD) assessment is a powerful prognostic factor for determining the risk of relapse in childhood acute lymphoblastic leukaemia (ALL). In this Swedish multi‐centre study of childhood ALL diagnosed between 2002 and 2006, the MRD levels were analysed in 726 follow‐up samples in 228 children using real‐time quantitative polymerase chain reaction (RQ‐PCR) of rearranged immunoglobulin/T‐cell receptor genes and multicolour flow cytometry (FCM). Using an MRD threshold of 0·1%, which was the sensitivity level reached in all analyses, the concordance between RQ‐PCR and FCM MRD values at day 29 was 84%. In B‐cell precursor ALL, an MRD level of ≥0·1% at day 29 predicted a higher risk of bone marrow relapse (BMR) with both methods, although FCM was a better discriminator. However, considering the higher median MRD values achieved with RQ‐PCR, a higher MRD cut‐off (≥0·2%) improved the predictive capacity of RQ‐PCR. In T‐ALL, RQ‐PCR was notably superior to FCM in predicting risk of BMR. That notwithstanding, MRD levels of ≥0·1%, detected by either method at day 29, could not predict isolated extramedullary relapse. In conclusion, the concordance between RQ‐PCR and FCM was high and hence both methods are valuable clinical tools for identifying childhood ALL cases with increased risk of BMR.

Serum biomarkers for atrophic gastritis and antibodies against Helicobacter pylori in the elderly: Implications for vitamin B12, folic acid and iron status and response to oral vitamin therapy

Objectives. To investigate the prevalence of serological markers for chronic atrophic gastritis (AG) and Helicobacter pylori antibodies (HPAb) in an elderly population, and to examine the interrelationship and significance for cobalamin, folic acid and iron status and response to oral vitamin therapy. Material and methods. The study included community-dwelling subjects (n=209), mean age 76 years, randomized to 4 month of oral daily treatment with 0.5 mg cyanocobalamin, 0.8 mg folic acid and 3 mg vitamin B6 or placebo (double-blind). Biochemical tests were carried out before and after treatment. Results. AG, as indicated by a pepsinogen I/II ratio <2.9, occurred in 14% (26/190) and HPAb in 54% (102/190) of the subjects. AG subjects had higher levels of serum methylmalonic acid (MMA) (p<0.001), plasma homocysteine (tHcy) (p<0.05), lower haemoglobin (Hb) (p<0.01) and a higher prevalence of vitamin B12 deficiency (p<0.01). HPAb was associated with AG, whereas AG subjects without HPAb had higher tHcy and MMA levels. There was no correlation between AG and iron status. Oral vitamin treatment led to greater (albeit non-significant) improvements in MMA, tHcy and total cobalamins in AG subjects compared to non-AG subjects. Conclusions. AG is a common condition and is a significant determinant of vitamin B12 status. AG is correlated to HPAB and lower Hb. Elderly AG subjects respond at least as well as non-AG subjects to oral treatment with B-vitamins in the doses employed.

Quality control of flow cytometry data analysis for evaluation of minimal residual disease in bone marrow from acute leukemia patients during treatment.

Low levels of leukemia cells in the bone marrow, minimal residual disease (MRD), are considered to be a powerful indicator of treatment response in acute lymphatic leukemia (ALL). A Nordic quality assurance program, aimed on standardization of the flow cytometry MRD analysis, has been established before implementation of MRD at cutoff level 10−3 as one of stratifying parameters in next Nordic Society of Pediatric Hematology and Oncology (NOPHO) treatment program for ALL. In 4 quality control (QC) rounds 15 laboratories determined the MRD levels in 48 follow-up samples from 12 ALL patients treated according to NOPHO 2000. Analysis procedures were standardized. For each QC round a compact disc containing data in list-mode files was sent out and results were submitted to a central laboratory. At cutoff level 10−3, which will be applied for clinical decisions, laboratories obtained a high concordance (91.6%). If cutoff level 10−4 was applied, the concordance would be lower (85.3%). The continuing standardization resulted in better concordance in QC3 and QC4 compared with QC1 and QC2. The concordance was higher in precursor B as compared with T-cell ALL. We conclude that after standardization, flow cytometry MRD detection can be reliably applied in international, multicenter treatment protocols.