Long-acting PGE2 and Lisinopril Mitigate H-ARS.

Thrombocytopenia is a major complication in hematopoietic-acute radiation syndrome (H-ARS) that increases the risk of mortality from uncontrolled hemorrhage. There is a great demand for new therapies to improve survival and mitigate bleeding in H-ARS. Thrombopoiesis requires interactions between megakaryocytes (MKs) and endothelial cells. 16, 16-dimethyl prostaglandin E2 (dmPGE2), a longer-acting analogue of PGE2, promotes hematopoietic recovery after total-body irradiation (TBI), and various angiotensin-converting enzyme (ACE) inhibitors mitigate endothelial injury after radiation exposure. Here, we tested a combination therapy of dmPGE2 and lisinopril to mitigate thrombocytopenia in murine models of H-ARS following TBI. After 7.75 Gy TBI, dmPGE2 and lisinopril each increased survival relative to vehicle controls. Importantly, combined dmPGE2 and lisinopril therapy enhanced survival greater than either individual agent. Studies performed after 4 Gy TBI revealed reduced numbers of marrow MKs and circulating platelets. In addition, sublethal TBI induced abnormalities both in MK maturation and in in vitro and in vivo platelet function. dmPGE2, alone and in combination with lisinopril, improved recovery of marrow MKs and peripheral platelets. Finally, sublethal TBI transiently reduced the number of marrow Lin-CD45-CD31+Sca-1- sinusoidal endothelial cells, while combined dmPGE2 and lisinopril treatment, but not single-agent treatment, accelerated their recovery. Taken together, these data support the concept that combined dmPGE2 and lisinopril therapy improves thrombocytopenia and survival by promoting recovery of the MK lineage, as well as the MK niche, in the setting of H-ARS.

Platelet factor 4 regulates T cell effector functions in malignant pleural effusions.

Malignant pleural effusion (MPE) is defined as the presence of tumor cells in pleural fluid and it is a fatal complication of advanced lung adenocarcinoma (LAC). To understand the immune response to the tumor in MPE, we compared the concentration of immunomodulatory factors in MPE of LAC and pleural effusion of heart failure (HF) patients by ELISA, and the proliferation and cytotoxic phenotype of T cells stimulated in the presence of LAC and HF pleural fluids by cytometry. Platelet factor 4 (PF4), vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-ß) and P-selectin levels were higher in LAC than in HF pleural fluids. However, plasmatic PF4 and P-selectin levels were similar in LAC and HF. VEGF positively correlated with TGF-ß and sPD-L1 in LAC but not in HF pleural fluids. LAC pleural fluids also inhibited T lymphocyte proliferation and cytotoxicity and reduced IL-17 production. PF4 levels inversely correlated with T cell function. The high content of PF4 in MPE was associated with poor prognosis. Our findings suggest that an impaired response of T lymphocytes induced by PF4 provides a significant advantage for tumor progression.

Riboflavin and ultraviolet illumination affects selected platelet mRNA transcript amounts differently.

BACKGROUND: Pathogen inactivation (PI) techniques use ultraviolet (UV) illumination with or without a photosensitizer to destroy pathogen RNA and DNA. Although lacking a nucleus and innate DNA transcription, platelets (PLTs) contain RNA and can synthesize proteins. The impact of PI on PLT protein synthesis and function is unknown; altered synthesis may affect overall PLT quality. In this study we determine to what extent PLT RNA is affected by PI. STUDY DESIGN AND METHODS: In a pool-and-split design, paired apheresis PLT concentrates were treated with riboflavin and UV illumination or were left untreated. PLT total RNA and mRNA amounts specific for glycoproteins (GP)IIIa, GPIIb, and GPIb; α-granule proteins PLT factor (PF)4; osteonectin and thrombospondin (TSP); and housekeeping protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were determined using absorbance and quantitative polymerase chain reaction. RESULTS: After treatment, amounts of all analyzed mRNAs were significantly reduced (p < 0.05), but to different degrees. For GAPDH and PF4, transcripts appeared less susceptible to the treatment, with 70% remaining 1 hour after UV illumination. For GPIIIa and TSP, less than 15% remained after treatment. There was a correlation (R(2) = 0.85) between transcript length and amount of mRNA remaining 1 hour after treatment. Total RNA demonstrated a life span equal to the PLT life span of 10 to 11 days. CONCLUSION: This is the first report of the impact of riboflavin and UV illumination on PLT mRNA. Results suggest that all mRNA present in PLTs is affected by the treatment although the degree of the effect varies among transcripts.

Automated multiplexed ECL Immunoarrays for cancer biomarker proteins.

Point-of-care diagnostics based on multiplexed protein measurements face challenges of simple, automated, low-cost, and high-throughput operation with high sensitivity. Herein, we describe an automated, microprocessor-controlled microfluidic immunoarray for simultaneous multiplexed detection of small protein panels in complex samples. A microfluidic sample/reagent delivery cassette was coupled to a 30-microwell detection array to achieve sensitive detection of four prostate cancer biomarker proteins in serum. The proteins are prostate specific antigen (PSA), prostate specific membrane antigen (PSMA), platelet factor-4 (PF-4), and interlukin-6 (IL-6). The six channel system is driven by integrated micropumps controlled by an inexpensive programmable microprocessor. The reagent delivery cassette and detection array feature channels made by precision-cut 0.8 mm silicone gaskets. Single-wall carbon nanotube forests were grown in printed microwells on a pyrolytic graphite detection chip and decorated with capture antibodies. The detection chip is housed in a machined microfluidic chamber with a steel metal shim counter electrode and Ag/AgCl reference electrode for electrochemiluminescent (ECL) measurements. The preloaded sample/reagent cassette automatically delivers samples, wash buffers, and ECL RuBPY-silica-antibody detection nanoparticles sequentially. An onboard microcontroller controls micropumps and reagent flow to the detection chamber according to a preset program. Detection employs tripropylamine, a sacrificial reductant, while applying 0.95 V vs Ag/AgCl. Resulting ECL light was measured by a CCD camera. Ultralow detection limits of 10-100 fg mL(-1) were achieved in simultaneous detection of the four protein in 36 min assays. Results for the four proteins in prostate cancer patient serum gave excellent correlation with those from single-protein ELISA.

Functional divergence between 2 chemokines is conferred by single amino acid change.

CXCL4 and CXCL4L1 are 2 closely related CXC chemokines that exhibit potent antiangiogenic activity. Because interactions with glycosaminoglycans play a crucial role in chemokines activity, we determined the binding parameters of CXCL4 and CXCL4L1 for heparin, heparan sulfate, and chondroitin sulfate B. We further demonstrated that the Leu67/His67 substitution is critical for the decrease in glycan binding of CXCL4L1 but also for the increase of its angiostatic activities. Using a set of mutants, we show that glycan affinity and angiostatic properties are not completely related. These data are reinforced using a monoclonal antibody that specifically recognizes structural modifications in CXCL4L1 due to the presence of His67 and that blocks its biologic activity. In vivo, half-life and diffusibility of CXCL4L1 compared with CXCL4 is strongly increased. As opposed to CXCL4L1, CXCL4 is preferentially retained at its site of expression. These findings establish that, despite small differences in the primary structure, CXCL4L1 is highly distinct from CXCL4. These observations are not only of great significance for the antiangiogenic activity of CXCL4L1 and for its potential use in clinical development but also for other biologic processes such as inflammation, thrombosis or tissue repair.

Normal ranges of angiogenesis regulatory proteins in human platelets.

Platelets sequester angiogenesis regulatory proteins early in tumor growth, which suggests a new avenue for monitoring disease. To date, there are no clinically relevant reference ranges for markers of early angiogenesis. We introduce a new ELISA-based method for accurate and reproducible measurement of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), platelet factor 4 (PF4), thrombospondin-1 (TSP-1), fibroblast growth factor, basic (bFGF), and endostatin in platelets. To facilitate clinical applicability, the platelet levels in isolated samples were determined utilizing a new actin ELISA method. Platelets from healthy donors at single and repetitive time points were used for the assessment of normal ranges of these proteins. The physiological levels in platelets were: VEGF (0.74 +/- 0.37 pg/10(6) platelets); PDGF (23 +/- 6 pg/10(6)); PF4 (12 +/- 5 ng/10(6)); TSP-1 (31 +/- 12 ng/10(6)); bFGF (0.44 +/- 0.15 pg/10(6)); and endostatin (5.6 +/- 3.0 pg/10(6)). There was an excellent correlation (R(2) = 0.7) between the platelet levels calculated with the actin ELISA and complete blood count. The levels of the platelets were higher than those in platelet-poor plasma by factors of: VEGF (215-fold); PDGF (914-fold); PF-4 (516-fold); TSP-1 (813-fold); and bFGF (17-fold). The endostatin levels were nearly equivalent. The biovariability of the platelet proteins in eight healthy subjects over a 5-week period was found to be minimal. We describe accurate and direct measurements of the concentrations of VEGF, bFGF, PDGF, TSP-1, endostatin, and PF4 in platelets of healthy human subjects. In contrast to the highly variable levels in plasma and serum, the platelet-derived measurements were accurate and reproducible with minimal biovariability.

Heparin-induced thrombocytopenia and cardiac surgery.

PURPOSE OF REVIEW: Heparin-induced thrombocytopenia (HIT) is an important, increasingly recognized antibody-mediated complication of heparin therapy occurring in approximately 0.5-5% of patients receiving heparin for at least 5 days. HIT is a prothrombotic disorder that typically presents with a 50% platelet count drop, thrombotic event manifesting usually 5-14 days after starting heparin, or both. HIT antibodies usually decrease to negative titers/levels within 3 months. When there is clinical suspicion of HIT, heparin should be discontinued and alternative anticoagulation should be considered, as well as laboratory evaluation for HIT. RECENT FINDINGS: HIT immunoassay results should be used for clinical decision-making about initial anticoagulation management. Recent data reevaluate the importance of absolute titers of HIT antibodies as a risk factor for clinical occurrence. Although laboratory assays are routinely used, current data suggest that increasing optical densities are more likely associated with a positive 14C-serotonin release assay and HIT. HIT is also associated with a greater risk for adverse events, so even though alternative anticoagulation is used, clinicians should be aware of this hypercoagulable syndrome. SUMMARY: For patients with HIT, alternative anticoagulation is available, but for cardiovascular surgery, if the operation cannot be delayed until HIT antibodies have become negative, alternative anticoagulation strategies are recommended, although patients with HIT are at a greater risk for adverse outcomes.

Plasmapheresis and heparin reexposure as a management strategy for cardiac surgical patients with heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) complicates the management of patients presenting for cardiac surgery, because high-dose heparin anticoagulation for cardiopulmonary bypass is contraindicated in these patients. Alternative anticoagulants are available, but there are concerns about dosing, efficacy, monitoring, thrombosis, and hemorrhage. METHODS: A retrospective chart review between November 2004 and March 2008 retrieved perioperative clinical and laboratory data for 11 adult cardiac surgical patients with a preoperative history of HIT and a current positive antiheparin/platelet factor 4 (anti-HPF4) antibody titer, who were managed with plasmapheresis and heparin anticoagulation. RESULTS: The median (interquartile range) preoperative anti-HPF4 antibody titer was 0.8 (0.7-2.2). Three of the 11 patients (27%) died of causes unrelated to HIT and 1 of these patients (9%) developed an ischemic foot, in the setting of cardiogenic shock, not thought to be HIT-related. A single plasmapheresis treatment reduced titers by 50%-84%, and 6 patients had negative titers after treatment; none of the 3 patients with reduced titers developed clinical HIT. CONCLUSIONS: This case series describes an alternative management strategy using intraoperative plasmapheresis for patients presenting for cardiac surgery with acute or subacute HIT. Reducing antibody load can potentially decrease the thrombotic risk associated with high anti-HPF4 titers and decrease the urgency to initiate postoperative anticoagulation in this patient group at high risk of postoperative bleeding.

Heparin-platelet factor 4 antibodies are frequent after vascular surgery but are not a frequent cause of graft thrombosis or thrombocytopenia.

OBJECTIVE: Approximately 10% of infrainguinal bypass surgeries are complicated by early conduit failure. The cause is unclear in most cases. A prospective study was conducted to monitor the development and function of platelet factor 4 (PF4)/heparin antibodies after infrainguinal bypass procedures and to evaluate their clinical significance in early graft occlusion. METHODS: Blood samples were obtained before surgery and at the 7-, 14-, and 28-day postsurgical evaluation. Relevant demographic and laboratory data were collected, and plasma samples were assayed for the presence and function of PF4/heparin-antibody by enzyme-linked immunosorbent assay (ELISA) and a two-point platelet aggregation assay. All tests were performed in duplicate or triplicate. RESULTS: Of the 79 patients who were enrolled, 67 reported previous heparin exposure. Six patients (7.6%) tested positive for the presence of PF4/heparin antibodies before surgery with ELISA, and four of these (67%) also had a positive result on the aggregation assay. During the 28-day follow-up, 22 subjects (32%) converted to positive according to the ELISA results; and five (22.7%) of these also tested positive for platelet-activating antibodies. No participants presented with thrombocytopenia or a >/=50% decrease in platelet count during the study period. Early graft occlusion was detected in three patients, all with negative ELISA and functional assay results throughout the study. CONCLUSION: Patients undergoing vascular surgery frequently develop PF4/heparin antibodies, with platelet-activating antibodies detected in up to 11% of these individuals. However, thrombocytopenia and vascular graft thrombosis both appear to be an uncommon consequence.

Quantitative interpretation of optical density measurements using PF4-dependent enzyme-immunoassays.

BACKGROUND: Many laboratories test for heparin-induced thrombocytopenia (HIT) using a PF4-dependent enzyme-immunoassay (EIA). An advantage of the EIA is its simplicity; a disadvantage is that it only indirectly detects heparin-dependent, platelet-activating antibodies ('HIT antibodies'). OBJECTIVES: To determine whether the magnitude of a positive EIA result, expressed in optical density (OD) units, predicts risk of HIT antibodies, defined as a strong-positive platelet serotonin-release assay (SRA) result (>or=50% serotonin release). PATIENTS/METHODS: We determined the risk of a strong-positive SRA result for five categories of OD reactivity (<0.40, 0.40-<1.00, 1.00-<1.40, 1.40-<2.00, and >or=2.00 OD units) using two EIAs (commercial anti-PF4/polyanion IgG/A/M and in-house anti-PF4/heparin-IgG). RESULTS: For patient sera investigated for HIT antibodies, a weak-positive result (0.40-<1.00 OD units) in either EIA indicated a low probability (or= 2.00 units. Quantifying the EIA-SRA relationship for 1553 referred patient sera, we found that for every increase of 0.50 OD units in the EIA-IgG, the risk of a strong-positive SRA result increased by OR = 6.39 [95% confidence interval (CI), 5.13, 7.95; P < 0.0001]. For every increase of 1.00 OD units in the EIA-IgG, the risk increased by OR = 40.81 (95% CI, 26.35, 63.20; P < 0.0001). CONCLUSIONS: The probability of HIT antibodies (strong-positive SRA result) inferred by a positive PF4-dependent EIA varies considerably in relation to the magnitude of the EIA result, expressed as OD values. In our laboratory, the probability of HIT antibodies being present reached >or=50% only when the OD level was >or=1.40 units.

Increased plasma concentrations of soluble CD40 ligand in acute coronary syndrome depend on in vitro platelet activation.

BACKGROUND: Soluble CD40 ligand (sCD40L) was suggested as a novel biomarker of cardiovascular risk. We examined the effect of preanalytical variation on the measurement of sCD40L concentration. METHODS: From healthy control individuals (n = 20) and patients with acute coronary syndrome (ACS) (n = 20) or sepsis (n = 20), we obtained blood drawn into 5 tubes containing citrate or a mixture of citrate, theophylline, adenosine, and dipyridamole (CTAD). The tubes were incubated for 30 min at room temperature or 0 degrees C before a single or double centrifugation (15 min, 2500 g) at room temperature or 4 degrees C, respectively. sCD40L, beta-thromboglobulin (betaTG), and platelet factor 4 (PF4) concentrations were measured using immunoassays. RESULTS: Concentrations of sCD40L were very low in all CTAD and citrated samples maintained at 0 degrees C (median < or = 0.076 microg/L). Although increased betaTG and PF4 confirmed disease-related in vivo platelet activation, sCD40L was not higher in patients than in controls. In contrast, if the samples were processed at room temperature, sCD40L was significantly higher in ACS patients than in controls (P <0.02 in CTAD and citrated plasma at room temperature). Moreover, the betaTG:PF4 ratio decreased in patient but not control CTAD samples, suggesting a greater susceptibility of patient platelets to in vitro activation. CONCLUSIONS: Increased sCD40L concentrations resulted from in vitro platelet activation during sample preparation. Disease-related in vivo activation did not contribute to sCD40L concentrations in plasma. Therefore, published studies of sCD40L demand cautious interpretation, because their preanalytical conditions were not standardized.

ProteinChip array profiling for identification of disease- and chemotherapy-associated biomarkers of nasopharyngeal carcinoma.

BACKGROUND: We previously used ProteinChip array profiling analysis to discover a serum biomarker associated with nasopharyngeal carcinoma (NPC). In this study, we used the same method to examine other biomarkers associated with NPC and response to chemotherapy (CT) in NPC patients. METHODS: We performed ProteinChip array analysis in 209 serum samples from 66 relapsed patients before and after salvage CT with gemcitabine and cisplatin or etoposide and cisplatin combinations, 11 patients in remission, and 35 healthy individuals. Intensities of the biomarker peaks were correlated with CT response of the patients and other clinical parameters. RESULTS: We discovered 13 candidate biomarkers associated with different clinical parameters. Two biomarkers (2803 and 3953 Da) were significantly increased in patients compared with controls at all stages of disease. Analysis of pre- and post-CT paired serum samples revealed 7 biomarkers correlated with impact of CT. Of these 7 biomarkers, 2 (2509 and 2756 Da) were significantly increased and 5 (7588, 7659, 7765, 7843, and 8372 Da) were significantly decreased post-CT in either 1 or both CT cohorts. Four biomarkers from pre-CT sera were correlated with CT response, with 3 (2950, 13 510, and 14 855 Da) being significantly decreased and 1 (6701 Da) significantly increased in patients who did not respond to CT. Tandem mass spectrometric sequencing and/or immunoaffinity capture assay identified the 3953 Da biomarker as a fragment of interalpha-trypsin inhibitor precursor and 7765 Da biomarker as platelet factor-4. CONCLUSIONS: Treatment-associated serum biomarkers found might serve to triage NPC patients for appropriate CT treatment.

Defective platelet responsiveness to thrombin and protease-activated receptors agonists in a novel case of gray platelet syndrome: correlation between the platelet defect and the alpha-granule content in the patient and four relatives.

BACKGROUND: We report a novel case of gray platelet syndrome (GPS). A 14-year-old boy had bleeding diathesis, mild thrombocytopenia, giant platelets with severe defect of alpha-granule secretory proteins, myelofibrosis and splenomegaly. METHODS AND RESULTS: Platelet function studies showed a marked reduction of aggregation and Ca(2+) mobilization by thrombin, protease-activated receptor 1 (PAR1)-activating peptide (AP) and PAR4-AP, PAR1 expression at 55% of normal levels, and a more than two hundred fold reduction of in vitro whole-blood thromboxane B(2) (TXB(2)) production. Sequencing of coding regions of the PAR1 gene failed to show abnormalities. This patient was initially classified as a sporadic case of GPS, as electron microscopy failed to identify giant platelets and/or alpha-granule deficiency in his relatives. However, further studies on the father and three other relatives showed a relative lack of platelet alpha-granule proteins by immunofluorescence microscopy, a defective platelet response to PAR4-AP, and severely reduced in vitro whole-blood TXB(2) production. On this basis, we suggest that in this family, GPS was transmitted in a dominant fashion with highly variable penetrance. CONCLUSIONS: Our study suggests that current diagnostic criteria fail to identify some patients with a mild GPS phenotype and that such patients might be identified by the methods cited above. It also better characterizes the pathogenesis of defective platelet responses to thrombin, and raises interesting questions on the correlation between abnormal PAR function and the lack of alpha-granule content in GPS.

Plasma glycoprotein V levels in the general population: normal distribution, associated parameters and implications for clinical studies.

Soluble glycoprotein V (sGPV) is a new plasma marker of thrombosis released from the platelet surface by thrombin. sGPV levels are increased in patients with atherothrombotic diseases, but the determinants of sGPV levels are unknown in the general population. Identification of these potential confounding factors is needed for correct design and analysis of clinical studies on cardiovascular diseases. The aim of this study was to determine the normal range of plasma values and the factors controlling sGPV levels in a population of normal individuals. Three hundred blood donors were recruited at the Etablissement Français du Sang-Alsace for the measurement of plasma levels of sGPV, platelet factor 4 (PF4), thrombin-antithrombin complexes (TAT) and D-dimers. The plasma level of sGPV was (median [interquartile range]) 27.5 [23.5-34.4] microg/l and displayed a Gaussian distribution. sGPV had a lower interindividual coefficient of variation (33%) than PF4 (176%), TAT (87%) or D-dimers (82%). sGPV levels were independent of age and sex but sensitive to red cell (r = 0.412; p < 0.0001) and platelet counts (r = 0.267; p = 0.001), total cholesterol (r = -0.313; p < 0.0001), food intake (r = 0.184; p = 0.0014) and smoking (r = -0.154; p = 0.039). Contrary to PF4 and TAT, sGPV did not differ between venous and arterial blood samples of 12 healthy individuals. Red cell and platelet counts, total cholesterol, current smoking and recent food intake are important determinants of sGPV levels and must be taken into account in clinical studies using sGPV as a thrombosis marker. Normal distribution of sGPV levels in the general population supports its use in clinical applications.

Comparison of changes in erythrocyte and platelet fatty acid composition and protein oxidation in advanced non-small cell lung cancer.

The formation of free radicals and lipid peroxidation products is linked both to carcinogenesis and tumor behavior. Blood samples from 50 patients with advanced (Stages III-IV) non-small cell lung cancer (NSCLC), and from 50 healthy volunteers were used for plasma beta-thromboglobulin (beta-TG) measurements, red blood cell (RBC) and platelet lipid analyses, and lipid fluorescence determinations. Samples from 15 randomly selected patients and 15 controls also were used for analysis of the expression of oxidized proteins. We observed: (a) higher levels of plasma beta-TG in patients, (b) alterations in membrane fatty acids. The RBC fatty acid profile changed especially in the 18-carbon species (increases in stearic and oleic and a decrease in linoleic fatty acids), and in arachidonic acid, which also decreased significantly. The platelet fatty acid profile mainly showed a decrease in arachidonic acid and a parallel increase in palmitic fatty acid; (c) the loss of polyunsaturated fatty acids (PUFA) in RBC and platelets could be correlated with changes in lipid extract fluorescence only for platelets; (d) protein oxidation levels were increased also only in the case of platelets. The changes detected point to platelet activation and lipid peroxidation processes associated with NSCLC. The oxidative stress affected RBC and platelets differently, although changes in PUFA might still have important physiological consequences in both types of cells.

Serum adenosine deaminase enzyme and plasma platelet factor 4 activities in active pulmonary tuberculosis, HIV-seropositive subjects and cancer patients.

The aim of this study was to determine the serum adenosine deaminase (ADA) and plasma platelet factor (PF-4) activities in patients with active pulmonary tuberculosis, HIV seropositive subjects, cancer patients (acute and chronic type lymphoblastic leukaemia) and to compare them with the results of healthy individuals. Eighty-eight subjects were enrolled in this study, 24 patients with active pulmonary tuberculosis, 20 patients with HIV seropositive subjects, 24 patients with cancer, 12 patients with acute type lymphoblastic leukaemia, 12 patients with chronic type lymphoblastic leukaemia) patients and 20 healthy individuals. ADA activity was determined in serum samples using colorimetric method and plasma PF4 activity was measured by using a sandwich-type enzyme immunoassay. When all study groups were compared with the control group, mean serum ADA activities were found to be significantly (p<0.01) higher in the sera of patients with active pulmonary tuberculosis (median, range: 39 IU/l), HIV seropositive subjects (median, range: 31 IU/l) than in the sera of cancer patients (median, range: 15) and healthy controls (median, range: 32 IU/l). Plasma PF-4 activities in active pulmonary tuberculosis patients (median, range: 84 IU/ml) were found to be significantly elevated when compared to HIV seropositive subjects (median, range: 59 IU/ml), cancer patients (median, range 55 IU/ml) and healthy individuals (median, range: 56 IU/ml) (p<0.01). Serum ADA and plasma PF-4 activities showed significant alteration in patients with active pulmonary tuberculosis compared to patients with HIV seropositive subjects, cancer patients and healthy individuals. In conclusion, we suggest that serum ADA and PF-4 activities can be used in the diagnosis of tuberculosis as an supplementary laboratory test in combination with clinical and laboratory findings. Further controlled studies are necessary to determine the importance of the PF-4 and ADA activities in patients with active pulmonary tuberculosis, HIV seropositive subjects and cancer patients.

Heparin-induced thrombocytopenia antibody and the pathogenesis of thrombotic microangiopathy after stem cell transplantation.

Thrombotic microangiopathy (TMA) that occurs after stem cell transplantation (SCT) is generally regarded as being different from thrombotic thrombocytopenic purpura (TTP), because it is reportedly not associated with deficiency of von Willebrand factor-cleaving protease, whereas this enzyme is deficient in TTP. However, better understanding of the pathogenesis of this condition is still required. Accordingly, we investigated the relationship between TMA occurring after SCT and heparin-induced thrombocytopenia (HIT), a condition related to low-dosed heparin therapy that features thrombocytopenia and generalized thrombotic disorders. Thirty-nine consecutive patients who underwent bone marrow transplantation were divided into a TMA group and a non-microangiopathy group (10 and 29 patients, respectively). Before SCT, the serum platelet factor 4 (PF4) levels of the TMA and non-microangiopathy groups were 0.123 +/- 0.023 and 0.132 +/- 0.025, respectively (p = NS). One week after recovery of the white blood cell count following transplantation, the TMA group (0.2902 +/- 0.0678) had a significantly higher PF4 level than the non-microangiopathy group (0.1548 +/- 0.0312) (p < 0.001, t-test). Thus, PF4 increased after engraftment of the transplanted stem cells in the patients who developed TMA. In patients who developed TMA, there was a significant correlation between the PF4 level and the grade of angiopathy according to the Zeigler grading system (p < 0.01 by linear regression analysis). These results suggest that a HIT antibody produced by donor cells may be involved in the development of TMA after SCT.