[The assessment of platelet function in patients with essential thrombocythemia]. / Ocena czynnosci plytek krwi u chorych na nadplytkowosc samoistna.

UNLABELLED: Essential thrombocythemia (ET) is associated with an increased risk of both thromboembolic and bleeding complications. Changes in platelet count and function are crucial but leukocyte activation is also suspected. The aim of the study. The study was designed to assess platelet function by optical and impedance platelet aggregometry and also PFA-100 analyser in ET patients at the time of diagnosis MATERIAL AND METHODS: The tests were performed in 32 ET patients. In each patient platelet aggregation tests by optical (in platelet rich plasma) and impedance methods (in whole blood) after stimulation with ADP, collagen, epinephrine were done. The platelet function was also assessed by PFA-100 method. The control group consisted of 20 healthy volunteers. RESULTS: In optical platelet aggregometry different platelet function abnormalities were seen in 31 patients (97%). The most frequent was decreased aggregation (19/32) with all used agonists but especially with epinephrine. Spontaneous aggregation was observed in 10 cases and in one we observed hyperaggregation. In whole blood platelet aggregometry abnormal results concerned 23 patients (72%). The most typical (14/32) was hyperactivity of platelets (especially after ADP). In this method we noted spontaneous aggregation in patients and in 4 patients' diminished aggregation. Mixed aggregation disturbances were observed in 6 patients. The closure time in the cohort of patients was significantly prolonged with both cartridges in comparison to control group and was outside reference ranges in 25/32 patient. No significant correlation between values of platelet aggregation in platelet rich plasma and in whole blood was found. No significant differences were observed between ET patients with and without clinical symptoms of bleeding/thrombosis although closure time with both cartridges was longer in patients with bleeding. CONCLUSIONS: In majority of ET patients different platelet function abnormalities are present. The platelet aggregation results depend on environment in which tests are performed. The PFA-100 seems to be a good method for detection of platelet defects in ET.

Circulating endothelial microparticles in patients with acute myocardial infarction.

BACKGROUND: Circulating endothelial microparticles (EMPs), the small vesicles released from altered endothelial cells, have been established as markers of endothelial injury. The elevated count of EMPs has been described in different conditions involving endothelial injury, including acute myocardial infarction (AMI). AIM: To assess the presence of EMP in patients with acute MI in relation to early clinical outcome and coronary angiography results. MATERIALS AND METHODS: EMPs counts were determined in 66 patients pts (23 women, 43 men) with documented ST elevation AMI and in 10 control patients with no evidence of coronary artery disease. All pts with AMI underwent coronary angiography with attempted primary angioplasty. EMPs were assayed by flow cytometry in platelet-poor plasma with combinations of fluorescent antibodies (anti CD31, -51, -42) allowing distinction of EMPs from platelet microparticles. Clinical and angiography results were compared with EMP levels. RESULTS: Three kinds of EMPs were measured: CD31+, CD51+ and CD31+/51+. The percentage of EMPs CD31+/CD51 was significantly (p=0,042) higher in patients with AMI in comparison with control subjects. However, a marker, which distinguished both groups the most, was the level of EMPs CD51+. It was significantly (p=0,024) higher in pts with AMI than in control pts. The levels of CD31+ were similar in both groups. There was no correlation between EMP levels, clinical and angiography results. CONCLUSION: The presence of circulating EMPs provides direct evidence of endothelial injury in AMI. The clinical and practical value of these results, however, needs further exploration.

The influence of low-dose aspirin and hydroxyurea on platelet-leukocyte interactions in patients with essential thrombocythemia.

Essential thrombocythemia is associated with an increased risk of thromboembolic complications. Recently, there has been a growing evidence that platelet-leukocyte interactions may contribute to pathogenesis of thrombosis in essential thrombocythemia. Low-dose aspirin (ASA) is generally recommended in the therapy of low-risk patients for thrombosis, whereas hydroxyurea in high-risk patients. The aim of the present study was to determine the effect of ASA and hydroxyurea on platelet, leukocyte functions and on formation of platelet/leukocyte conjugates in vivo in patients with essential thrombocythemia. Markers of platelet and leukocyte activation were assessed in 40 patients with essential thrombocythemia at diagnosis and in 20 controls using flow cytometry assays. In second part of the study, the tests were repeated after either ASA treatment (in 25 low-risk patients) or hydroxyurea therapy (in 15 high-risk patients). On diagnosis, significantly elevated expression of P-selectin on platelets (4.98 +/- 3.31 vs. 0.99 +/- 0.69 P < 0.001) and increased percentage of platelet-polymorphonuclear leukocyte CD11b/CD42b conjugates [10.12 (4.21-31.22) vs. 3.17 (1.43-5.99) P < 0.001] and platelet-monocyte CD11b/CD14/CD61 conjugates [36.62 (12.23-51.62) vs. 13.86 (7.14-23.51) P < 0.001] were found in essential thrombocythemia group as compared with the healthy control group. Therapy with ASA significantly reduced platelet-polymorphonuclear leukocyte [10.72 (4.21-26.97) vs. 8.12 (1.13-26.94) P < 0.05] and platelet-monocyte conjugates [38.6 (13.45-51.62) vs. 25.76 (13.52-45.02) P < 0.05]. Surprisingly, therapy with hydroxyurea was poorly effective in reduction of platelet/leukocyte conjugates. These data document an increased platelet and leukocyte activation at the time of diagnosis. This is the first report showing enhanced platelet-leukocyte aggregate formation in low-risk essential thrombocythemia patients and the efficacy of ASA in its reduction.

The distribution of peripheral blood dendritic cells assayed by a new panel of anti-BDCA monoclonal antibodies in healthy representatives of the polish population.

A growing number of studies are being performed on the role of dendritic cells (DCs) in the etiopathogenesis of various conditions. Therefore, it is extremely important to establish the best comparable methods for the determination of the absolute count of blood dendritic cells (BDCs) or their subsets, and the reference normal values for comparisons. The aim of our study was to assess a normal profile of BDCs in the non-cultured human blood of healthy Polish volunteers. BDCs were detected among peripheral blood mononuclear cells (PBMC) from 99 healthy people, aged 18-56. Based on the panel of novel anti-BDCA1, BDCA2 and BDCA3 monoclonal antibodies (MoAbs), three main subpopulations of BDCs were distinguished: two myeloid types of BDCs, MDC1(BDCA-1+/ CD11c+ /HLA-DR+) or MDC2 (BDCA-3+/CD32-/CD64-/HLA-DR+), and a plasmacytoid subtype, PDC (BDCA-2+/CD123+/HLA-DR+). The number and percentage of BDCs were correlated with the age, gender, photosensitivity (phototype, minimal erythemal dose -- MED) and morphological parameters of the healthy volunteers. BDCs represented 0.83% of the PBMC and the median total BDC number was 44.0 cell/microl. The total BDC number correlated with the WBC count (rho=0.40, p=0.001) as well as with the lymphocyte and monocyte counts (rho=0.20, p=0.045 and rho=0.26, p=0.009, respectively). The median percentage of the MDC1 count (0.20%) was twice as high as the MDC2 count (0.10%). The median PDC count was 28.2 cell/microl, and these cells represented 0.50% of the PBMC. There was a positive correlation between PDC and skin photosensitivity (rho=0.28, p=0.005). An inverse correlation between the PDC count and the age of the examined volunteers was also found (rho=-0.22, p=0.029). Our study provides the first referential data on normal rates and counts of BDCs and their subpopulations, assessed by the new panel of anti-BDCA MoAbs, in healthy Polish subjects. The method used in the study allowed the determination of BDCs and their subset numbers in a relatively small blood volume.