Performance evaluation of the automated nucleated red blood cell count of five commercial hematological analyzers.

INTRODUCTION: Recent automated hematology analyzers (HAs) can identify and report nucleated red blood cells (NRBC) count as a separate population out of white blood cells (WBC). The aim of this study was to investigate the analytical performances of NRBC enumeration on five top of the range HAs. METHODS: We evaluated the within-run and between-day precision, limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) of XE-2100 and XN-module (Sysmex), ADVIA 2120i (Siemens), BC-6800 (Mindray), and UniCel DxH 800 (Beckman Coulter). Automated NRBC counts were also compared with optical microscopy (OM). RESULTS: The limits of detection for NRBC of the BC-6800, XN-module, XE-2100, UniCel DxH 800, and ADVIA 2120i are 0.035×109 /L, 0.019×109 /L, 0.067×109 /L, 0.038×109 /L, and 0.167×109 /L, respectively. Our data indicated excellent performance in terms of precision. The agreement with OM was excellent for BC-6800, XN-module, and XE-2100 (Bias 0.023, 0.019, and 0.033×109 /L, respectively). ADVIA 2120i displayed a significant constant error and UniCel DxH 800 both proportional and small constant error. CONCLUSION: Regards to NRBC counting, the performances shown by BC-6800, XN-module, and XE-2100 are excellent also a low count, ADVIA 2120i and UniCel DxH 800 need to be improved.

Reliability of automated synovial fluid cell counting with Mindray BC-6800 body fluid mode.

INTRODUCTION: The enumeration and differentiation of nuclear elements in synovial fluid is a cornerstone for diagnosis and follow-up of many orthopedic and rheumatologic diseases. In this study, we evaluated the analytical performance of Mindray BC-6800 BF mode (BC-6800-BF) for synovial fluid analysis. METHODS: Overall, 78 synovial fluids were collected and analyzed with both BC-6800-BF and light microscopy. The study also entailed the assessment of limit of blank (LoB), limit of detection (LoD), limit of quantification (LoQ), carryover and linearity. RESULTS: The LoB for the parameters total cells and white blood cells was 6 × 106 cells/L, and the LoD and LoQ were instead 15 and 16 × 106 cells/L, respectively. Linearity was excellent and carryover was negligible. The agreement between BC-6800-BF and light microscopy was satisfactory for all samples pretreated with hyaluronidase, displaying a bias between -5.9% and 8.2%. CONCLUSIONS: The use of BC-6800-BF for synovial fluid analysis enables rapid and accurate assessment, especially for total cell and polymorphonuclear counts. The use of BC-6800-BF may therefore allow the replacement of optical analysis, especially in samples pretreated with hyaluronidase, thus allowing its routine use for the screening of synovial specimens.

Intense Foxp3+ CD25+ regulatory T-cell infiltration is associated with high-grade cutaneous squamous cell carcinoma and counterbalanced by CD8+/Foxp3+ CD25+ ratio.

BACKGROUND: Recent reports have revealed the therapeutic potential of cell-mediated immunity in neoplasms such as cutaneous squamous cell carcinoma (SCC). OBJECTIVES: To define the antigenic coexpression of regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) and assess the CD8(+) /Foxp3(+) CD25(+) cell ratio at peritumoral and intratumoral levels in order to investigate a correlation with the aggressiveness of SCC tumours. METHODS: We evaluated the content and distribution of Foxp3(+) CD25(+) Treg and CD123(+) pDC infiltration and assessed CD8(+) /Foxp3(+) CD25(+) cell ratio at peritumoral and intratumoral levels in 40 SCCs (20 well-differentiated, G1; and 20 moderately to poorly differentiated, G2-G3) to investigate a correlation with their aggressiveness. We determined the profiles of Tregs and CD123(+) cells; immunostained for CD4, CD8, CD123, interleukin (IL)-1 and transforming growth factor (TGF)-ß1; and unequivocally double stained for Foxp3CD25. RESULTS: Peritumorally, CD4, CD8 and Foxp3 expression showed no difference between the two groups. CD123(+) cells were fewer in G2-G3 (P = 0·0005), while Foxp3(+) CD25(+) cells were more numerous (P = 0·0005). The Foxp3(+) CD25(+) /Foxp3(+) ratio was higher in G2-G3 cases (P = 0·0005), confirming the trend in this group of activated T lymphocytes towards total Treg Foxp3(+) cells, while the CD8(+) /Foxp3(+) CD25(+) ratio was higher in G1 (P = 0·0005). Intratumorally, CD4(+) and CD8(+) cells infiltrated G2-G3 (P = 0·048) more than G1 (P = 0·004), whereas almost all cells were CD123 negative. Regarding Foxp3CD25, TGF-ß1 and IL-10, they were less expressed in G1, whereas they were positive in G2-G3 (P < 0·05). The CD8(+) /Foxp3(+) CD25(+) ratio was similar to that observed in peritumoral infiltration. CONCLUSIONS: Our data suggest that intratumoral recruitment of Tregs, high expression of TGF-ß1 and IL-10, almost negative CD123+, and a low CD8(+) /Foxp3(+) CD25(+) T-cell ratio may contribute to the aggressiveness of cutaneous SCC, as already evidenced for other solid tumours.

Does asymmetric dimethylarginine (ADMA) plasma concentration predict esophageal varices in patients with cirrhosis?

BACKGROUND: In previous studies elevated Asymmetric NG, NG - dimethylarginine (ADMA) plasma levels, an endogenous nitric oxide synthase inhibitor, correlated with the severity of hepatic venous pressure gradient measurement, both in peripheral and in hepatic veins. The aim of this study was to explore whether elevated ADMA plasma levels were able to predict the presence of esophageal varices (EV) and/or large EV in patients with cirrhosis. METHODS: 74 cirrhotic patients who had undergone elective upper gastrointestinal endoscopy in order to assess the presence of portal hypertension and predictors of EV and/or large EV. ADMA levels were assayed by an ELISA test (Immundiagnostik AG, Germany). RESULTS: 53 patients had EV (26/53 had large EV). Univariate analysis of low hemoglobin (p = 0.045), PT-INR (p = 0.003), albumin (p = 0.024), bilirubin (p = 0.036), Child-Pugh score (p = 0.026), and ascites (p = 0.036) predicted the presence of EV. Multivariate analysis predicted EV for only PT-INR. The presence of large EV was predicted with univariate analysis of ADMA plasma levels (p = 0.013), low hemoglobin (p < 0.001), PT-INR (p = 0.001), albumin (p = 0.001), bilirubin (p = 0.026), Child-Pugh score (p < 0.001), ascites (p = 0.004). Sensitivity, specificity, predictive positive and negative values of ADMA plasma level > 0.5 micromol/L(-1) in predicting large EV were 0.69 (95% CI 0.53 - 0.82), 0.51 (95% CI 0.40 - 0.62), 0.43 (95% CI 0.31 - 0.56), 0.76 (95% CI 0.62 - 0.86), while the area under the ROC curve was 0.65 (95% CI 0.51 - 0.79). CONCLUSIONS: ADMA plasma levels were increased in cirrhotics with more advanced liver failure but did not prove to be a useful clinical tool for predicting the presence of esophageal varices or large esophageal varices.

Assessing Serum Concentrations of 25-Hydroxy-Vitamin D in North-Western Italy.

OBJECTIVES: Backgound: Most of the published studies on vitamin D levels in Italy have been performed in specific age- or disease- subgroups. Few data are available on the status of vitamin D in the adult general population. OBJECTIVE: We report on vitamin D levels of a large sample of adults from North-Western Italy. Association with age, sex, and season is also evaluated. PARTICIPANTS: 13,110 cases (24% men, 76% women; median age 67 [interquartile range, IQR, 56-77] years old) were collected in the North-Eastern of Piedmont (Italy). MEASUREMENTS: 25-OH-vitamin D levels were measured by chemiluminescent immunoassay. RESULTS: Median total vitamin D level was 19.9 ng/ml (IQR 11.2-28.8 ng/ml) with up to 3,592 (27.4%) and 10,185 (77.7%) subjects respectively below 12 and 30 ng/ml. Vitamin D levels were significantly higher in women than in men (20.5 vs 18.1 ng/ml; p<0.001), in summer than in winter (21.4 vs 18.5 ng/ml; p<0.001), and in individuals aged ≤45years or 46-64 years than in those older than 65 years (20.3 and 21.3 vs 18.8 ng/ml). The lowest mean vitamin D levels were reported during the winter season by men aged ≥65 years (14.7 ng/ml) and 46-64 years (16.8 ng/ml). Multivariate analysis confirmed that age (p<0.001), sex (p=0.002), season (p<0.001) and their interaction (p=0.03) were independently associated to vitamin D concentrations. CONCLUSIONS: This study clearly shows that the majority of adult Italian population, living in a sunny and highly urbanized area of North-Western Italy, have an important deficiency in vitamin D. However, these data must be interpreted with caution if considering the lack of standardization of vitamin D assays.

Role of the laboratory in monitoring patients receiving dual antiplatelet therapy.

INTRODUCTION: The increasing demand for therapeutic monitoring in patients receiving antiplatelet therapy has been paralleled by the development of instruments and tests whose clinical usefulness is still under debate. We devised a laboratory approach to detect patients with antiplatelet resistance at risk to develop thrombotic events. METHODS: One hundred and eighty patients, under aspirin and clopidogrel after angioplasty and stent implantation, were studied by PFA100(®) with collagen/epinephrine (CoEPI, cutoff 165s) cartridge and by Multiplate(®) using arachidonic acid (ASPItest, pos < 862AUC), ADP (ADPtest, pos < 417AUC), and collagen (COLtest, pos < 607AUC). RESULTS: Only 67 of 173 patients with ASPI < 862 displayed a prolonged CoEPI and up to 65 patients had normal CoEPI despite ASPI < 300. Patients with ASPI < 300 had significantly lower COL than patients with ASPI > 300. One hundred and thirty-eight patients displaying ADP < 417 had significantly lower COL than those with ADP > 417. Association between COL and ADP remained after ASPI stratification: in patients with suboptimal (ASPI 300-892) or maximal (ASPI < 300) response to aspirin, having ADP < 417 (clopidogrel responsive) increased COL positivity, respectively, from 9.5 to 58.8% and from 47.6 to 82.7%. CONCLUSION: A combination of specific tests may be useful in identifying higher-risk patients with poor compliance or drug resistance who potentially may benefit from therapy change.

Side effects associated with ultrarapid cytochrome P450 2D6 genotype among women with early stage breast cancer treated with tamoxifen.

BACKGROUND: The side effects of tamoxifen, a drug widely used for the treatment and the prevention of recurrence in patients with estrogen receptor positive breast cancers (ER+), have been reported in clinical trials, but to date no information is available on their possible association with an increased enzymatic activity of CYP2D6 (ultra-metabolizers, UMs). The aim of this study was therefore to evaluate the association between the presence of multiple functional CYP2D6 alleles and the occurrence of side effects. METHODS: 61 women with ER+ breast cancer receiving tamoxifen monotherapy were investigated in order to assess the relationships between CYP2D6 UM phenotype and side effects. Genotyping of 16 CYP2D6 polymorphisms was performed using a new DNA microarray technology. RESULTS: A highly significant difference was detected (41.2% of difference, 95% CI 6 - 61%, Fisher's exact test, p = 0.030) between the numbers of Ultrarapid Metabolizer patients (UM; high activity) with two or more adverse drug reactions to tamoxifen (7/9; 77.8%), compared to the number of Extensive Metabolizers (EM; normal activity), Intermediate Metabolizers (IM; reduced activity), and Poor Metabolizers (PM; no activity) with at least two side effects (19/52, 36.5%). A similar difference was also observed comparing the two groups (UM vs EM-IM-PM) for the number of side effects (median and inter quartile range, IQR: AM/EM/IM 1, IQR 0-2 vs. ULTRA 2, IQR 2-4; Mann-Whitney p = 0.005). CONCLUSIONS: Our results suggest a new association between CYP2D6 gene duplication and side effects to tamoxifen, indicating a possible role of CYP2D6 in their occurrence.

Conformational anti-cytochrome P4502E1 (CYP2E1) auto-antibodies contribute to necro-inflammatory injury in chronic hepatitis C.

Circulating auto-antibodies against cytochrome P4502E1 (CYP2E1) have been observed in a significant fraction of patients with chronic hepatitis C (CHC). This study investigated the clinical significance of these auto-antibodies in relation to their antigen specificity. The presence of anti-CYP2E1 IgG was investigated in 137 consecutive patients with biopsy-proven CHC. Anti-CYP2E1 IgG above control threshold levels was detected in 52 (38%) subjects. By combined immunoprecipitation and western blotting, we observed that among anti-CYP2E1 IgG-positive sera, 23 (44%) were unreactive towards denaturated CYP2E1, indicating a prevalent recognition of conformational CYP2E1 antigens. Conformational anti-CYP2E1 auto-antibodies were unrelated to circulating gamma-globulins, alcohol intake or infection by specific HCV genotypes. The presence of anti-CYP2E1 auto-antibodies was associated with an 11-fold (OR 10.9 95%CI 1.4-86.6 P = 0.008) increased prevalence of necro-inflammatory grading ≥ 4 (Ishack's criteria) and 4-fold (OR 4.0; 95%CI 1.3-11-7: P = 0.014) increased prevalence of fibrosis staging ≥ 2, respectively. Multivariate analysis confirmed conformational anti-CYP2E1 IgG (P = 0.005) and age (P = 0.033) as independent predictors of necro-inflammatory grading ≥ 4. The development of anti-CYP2E1 auto-antibodies targeting conformational CYP2E1 epitopes is associated with more severe liver damage in CHC.

Serum autoantibodies against cytochrome P450 2E1 (CYP2E1) predict severity of necroinflammation of recurrent hepatitis C.

We previously reported that autoantibodies against cytochrome P4502E1 (CYP2E1) are frequent in patients with chronic hepatitis C. As autoimmune reactions are increasingly detected after orthotopic liver transplantation (OLT), this study investigates prevalence and significance of anti-CYP2E1 autoantibodies in 46 patients with post-OLT recurrent hepatitis C. IgG against recombinant human CYP2E1 above the control threshold was detected in 19 out 46 (41%) sera collected immediately before OLT and in 15 out 46 (33%) sera collected at the time of the 12 months follow-up liver biopsy. Although anti-CYP2E1 reactivity was not modified by OLT, the patients with persistently elevated anti-CYP2E1 IgG (n = 12; 26%) showed significantly higher prevalence of recurrent hepatitis with severe necroinflammation and fibrosis than those persistently negative or positive only either before or after OLT. Moreover, the probability of developing severe necroinflammation was significantly higher in persistently anti-CYP2E1-positive subjects. Multivariate regression and Cox analysis confirmed that the persistence of anti-CYP2E1 IgG, together with a history of acute cellular rejection and donor age >50 years, was an independent risk factor for developing recurrent hepatitis C with severe necroinflammation. We propose that autoimmune reactions involving CYP2E1 might contribute to hepatic damage in a subgroup of transplanted patients with recurrent hepatitis C.

Antibodies against oxidized phospholipids in laboratory tests exploring lupus anti-coagulant activity.

Lupus anti-coagulants (LA) are a variety of anti-phospholipid antibodies characterized by their capacity to interfere with phospholipid-dependent coagulation assays. LA are increasingly recognized as important predictors of thrombosis. However, the antigen specificity of LA is still poorly characterized. Growing evidence indicates that oxidized phospholipids are among the targets of anti-phospholipid antibodies. This prompted us to investigate the role of IgG directed against different oxidized phospholipids in 164 subjects without clotting factor defects that were tested for the presence of LA using a LA-sensitive activate partial thromboplastin time (aPTT-FSL) and a screening/confirmation assay based on diluted Russell's viper venom test (dRVVT-PL). The response to aPTT-FSL was significantly (P < 0.0005) associated with high titres of IgG against oxidized phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol, whereas positivity to dRVVT-PL was associated with the elevation of IgG against oxidized phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine (P < 0.0005) and phosphatidylinositol (P < 0.01). No difference in reactivity against oxidized cardiolipin was evident between the different groups. Positivity to the dRVVT-PL test was also associated significantly (P < 0.005) with the elevation of anti-cardiolipin and anti-beta(2)-glycoprotein-1 IgG. However, stepwise logistic regression demonstrated that IgG recognizing oxidized phosphatidylethanolamine and oxidized phosphatidylcholine were the only independent predictors of the response to dRVVT-PL assay, while IgG recognizing oxidized phosphatidylethanolamine and oxidized phosphatidylinositol were independent predictors of the response to aPTT-FSL test. In conclusion, autoantibodies against defined oxidized phospholipids are independent predictors of LA detection by aPTT-FSL or dRVVT-PL assays and might contribute to the variability often observed in the responses to the functional tests detecting LA.

Bilateral congenital anterior diaphragmatic hernia: a case report.

The anteromedial diaphragmatic hernias of Morgagni and Larrey are the least common defects that occur in this organ. Simultaneous occurrence has been described but remains an absolute rarity. We herein present a case of this bilateral herniation with a unique presentation. The paper refers to the basic anatomic, diagnostic and therapeutic considerations for this entity.

Review article: role of oxidative stress in the progression of non-alcoholic steatosis.

The mechanisms responsible for the progression of nonalcoholic fatty liver disease (NAFLD) to more severe liver injury are still poorly understood. Data from animal models suggest that oxidative stress contributes to steatohepatitis and an increase of lipid peroxidation has been documented in human NAFLD. By measuring the titers of circulating antibodies against lipid peroxidation products as markers of oxidative stress we have observed that NAFLD patients have titers of these antibodies significantly higher than in controls. Moreover, the titers of lipid peroxidation-related antibodies are associated with a 3-fold increase in the risk of developing advanced fibrosis/cirrhosis. Although the mechanisms causing oxidative stress in NAFLD have not been elucidated, these results support the involvement of lipid peroxidation in the processes leading to liver fibrosis associated with NAFLD.

Immune response towards lipid peroxidation products as a predictor of progression of non-alcoholic fatty liver disease to advanced fibrosis.

AIMS: Factors responsible for the progression of non-alcoholic fatty liver disease (NAFLD) to more severe liver injury are poorly understood. In the present study, we investigated the association between immune reactions triggered by oxidative stress and stage of NAFLD. METHODS: Titres of IgG against human serum albumin adducted with malondialdehyde (MDA-HSA) or arachidonic acid hydroperoxide (AAHP) and against oxidised cardiolipin (Ox-CL) were measured in 167 NAFLD patients with steatosis only (n = 79), steatohepatitis (n = 74), or steatosis plus cirrhosis (n = 14), and in 59 age and sex matched controls. RESULTS: Circulating IgG against lipid peroxidation products was significantly higher (p<0.001) in NAFLD patients than in controls. Oxidative stress dependent immune responses were not associated with obesity, type 2 diabetes, or with serum cholesterol, ferritin, or aminotransferase levels. Titres of lipid peroxidation related antibodies were also independent of the extent of steatosis and were similarly distributed in patients with and without necroinflammation. In contrast, the same antibodies were significantly increased in patients with advanced fibrosis or cirrhosis. Logistic regression analysis confirmed that anti-MDA antibodies were independently associated with progression of NALFD and that NAFLD patients with titres of anti-MDA-HSA antibodies above the control threshold value had a threefold (relative risk 2.82 (95% confidence interval 1.35-5.90); p = 0.007) higher risk of having advanced fibrosis/cirrhosis than patients whose antibody titres were within the control range. CONCLUSIONS: These results indicate that the presence of immune reactions triggered by oxidative stress can be an independent predictor of progression of NAFLD to advanced fibrosis.

Antiphospholipid antibodies associated with alcoholic liver disease specifically recognise oxidised phospholipids.

BACKGROUND: Circulating antiphospholipid antibodies (aPL) are often detected in patients with alcoholic liver disease (ALD) but little is known about the causes of their formation. AIMS: We have evaluated whether ethanol mediated oxidative injury might promote the development of aPL in ALD. PATIENTS AND METHODS: IgG against beta(2) glycoprotein 1 (beta(2)-GP1), cardiolipin, and human serum albumin (HSA) complexed with either oxidised arachidonic acid (HSA-APP) or malondialdehyde (HSA-MDA) were assayed by ELISA in heavy drinkers with or without ALD and in healthy subjects. RESULTS: Circulating IgG recognising cardiolipin were significantly higher in ALD patients than in controls. However, anticardiolipin reactivity of ALD sera was only evident using, as the antigen, oxidised cardiolipin but not oxidation protected cardiolipin. In ALD patients, individual values of IgG antioxidised cardiolipin were associated with the titres of antibodies against HSA-MDA and HSA-APP (r=0.68 and 0.72, respectively; p<0.0001) used as markers of oxidative stress. ALD patients also displayed increased levels of antibodies against phospholipid binding protein beta(2)-GP1, and individual reactivity towards oxidised cardiolipin and beta(2)-GP1 were highly correlated (r=0.85; p<0.0001). IgG binding to oxidised cardiolipin, HSA-MDA, and HSA-APP was also significantly higher in beta(2)-GP1 positive than in beta(2)-GP1 negative sera. However, preadsorption of beta(2)-GP1 positive sera on beta(2)-GP1 coated ELISA plates reduced reactivity to oxidised cardiolipin by 80%, without affecting that to HSA-APP or HSA-MDA. CONCLUSIONS: Ethanol induced oxidative injury is associated with the development of antibodies targeting complexes between oxidised cardiolipin and beta(2)-GP1. These antibodies might account for high aPL titres observed in patients with severe ALD.

Circulating antibodies recognizing malondialdehyde-modified proteins in healthy subjects.

Antibodies against malondialdehyde (MDA)-modified proteins are often increased in patients with diseases related to oxidative stress. However, the clinical significance of these antibodies is hampered by their frequent presence also in healthy controls. Aim of this work has been to characterize the immune reactivity against MDA-derived antigens in healthy subjects. The sera of 120 healthy subjects contained IgG and IgM targeting MDA-modified human albumin (HSA), fibrinogen, and LDL. These sera also displayed weak reactivity with oxidized LDL and HSA complexed with oxidized arachidonic acid. Conversely, oxidized HSA or HSA complexed with other aldehydic lipid peroxidation products was not recognized. Control sera also did not recognize cyclic dihydropyridine-MDA products, while HSA-MDA reactivity was associated (r > 0.9; p <.0005) with the presence of fluorescent lysine-conjugated-imine cross-links. In Western blots both IgG and IgM recognized high molecular weight HSA-MDA aggregates, but not monomeric HSA-MDA adducts. The addition of sodium cyanoborohydride, that prevented conjugated-imine fluorescence and protein aggregation during HSA-MDA preparation, abolished the antibody binding. This suggested that the plasma of healthy subjects contained IgG and IgM recognizing protein aggregates linked through 1-amino-3-imino-propene bridges. The function of these antibodies is at the moment unknown, but they might contribute to scavenging MDA cross-linked proteins.

Antibodies against advanced glycation end product Nepsilon-(carboxymethyl)lysine in healthy controls and diabetic patients.

AIMS/HYPOTHESIS: Nepsilon-(carboxymethyl)lysine (CML) is one of the end products of protein glycoxidation and its accumulation is associated with diabetes complications. Since CML-modified proteins are immunogenic, we have investigated the presence of anti-CML antibodies in diabetic patients. METHODS: Antibodies against CML-modified human serum albumin (HSA) were measured by direct enzyme-linked immunosorbent assay in the sera from 289 non-selected diabetic and in 120 healthy control subjects. RESULTS: Immunoglobulin-G reactivity towards CML-HSA was significantly higher in diabetic than in control sera. The presence of anti-CML IgG in diabetics, however, was not influenced by age, duration of disease or glycaemic control. Analysis of distribution frequency revealed that anti-CML IgG in both control and diabetic subjects were not normally distributed and that the distribution curves were similar in the two groups. Moreover, only 14% of the diabetic subjects displayed antibody binding to CML-HSA above 95 centile in the control cohort. Competition experiments confirmed that the IgG detected in both control and diabetic groups were specific for CML epitopes and did not recognise glycated-HSA in which CML formation was inhibited. CONCLUSION/INTERPRETATION: The presence of anti-CML IgG in diabetic sera is probably not related to the development of an immune response against protein glycoxidation products.

Action of antitumoral platinum complexes on in vitro platelet functions.

This report presents a comparison of the effects of cis- and trans-diamminedichloroplatinum complexes on in vitro platelet functions. Pretreatment of platelets with cis-platinum (cisplatin) induced a slow, dose-dependent (0.1-0.45 mM), increase in the cytosolic Ca2+ concentration, pleckstrin (47 kDa) phosphorylation and serotonin secretion, as well as a slight shape modification with emission of a few pseudopodia. All these effects were remarkably increased in platelets exposed to trans-platinum (transplatin). The rise in cytosolic Ca2+ concentration and serotonin secretion evoked by stimulation of platelets with thrombin were not significantly influenced by cellular exposure to cis-platinum, whereas they were enhanced and inhibited, respectively, by exposure to trans-platinum. Trans-platinum also inhibited thrombin-promoted platelet aggregation to a greater extent than the cis-isomer. While the viscosity of platelet rich-plasma tended to decrease in the presence of cis-platinum, it tended to increase in the presence of trans-platinum. Taken together, these results indicate that the effects on platelet functions of the efficacious antitumor complex cis-platinum is rather different from that of the inactive complex trans-platinum. Therefore, the in vitro tests of platelet functions employed in this study might provide an index of antitumor drug toxicity and serve as a preliminary indicator of therapeutic efficacy.