Diagnosing empty iron stores in women: unbound iron binding capacity (UIBC) versus soluble transferrin receptor (sTFR).

Unbound iron binding capacity (UIBC) is more accurate than total iron binding capacity (TIBC) and percent transferrin saturation in diagnosing empty iron stores. It is unknown whether UIBC is more or less accurate than soluble transferrin receptor (sTFR). We obtained public-use data from the U.S. National Health and Nutrition Examination Survey (NHANES) 2005-2006 to compare the accuray of UIBC and sTFR in diagnosing empty iron stores in 2337 women aged 12-49 years. We grouped the women according to CRP less than 5 mg/L and pregnancy (four groups) and used three definitions of empty iron stores: Serum ferritin less than 10, 15, and 20 µg/L. Receiver operating characteristic (ROC) curve analysis was used to estimate the diagnostic accuracy. UIBC showed a better diagnostic accuracy than sTFR in all groups and definitions of empty iron stores, except in nonpregnant women with CRP at least 5 mg/L when empty iron stores were defined as ferritin less than 10 and 15 µg/L. Two differences reached statistical significance: In nonpregnant women without inflammation the area under the ROC curve for UIBC was 0.830 compared to 0.793 for sTFR (p = .007) when empty iron stores were defined as ferritin less than 20 µg/L. The corresponding figures for pregnant women without inflammation were 0.843 for UIBC and 0.739 for sTFR (p = .003). In conclusion, UIBC is a more accurate test than sTFR in diagnosing empty iron stores in women without inflammation.

Delayed elimination of high-dose methotrexate and use of carboxypeptidase G2 in pediatric patients during treatment for acute lymphoblastic leukemia.

BACKGROUND: Carboxypeptidase G2 (CPDG2 ) can be used as rescue treatment in cases of delayed methotrexate elimination (DME) and Mtx-induced nephrotoxicity. PROCEDURE: Between July 2008 and December 2014, all children (1.0-17.9 years) in the Nordic countries diagnosed with Philadelphia chromosome negative acute lymphoblastic leukemia (ALL) were treated according to the Nordic Organization for Pediatric Hematology and Oncology (NOPHO) ALL 2008 protocol, including administration of six to eight high-dose (5 g/m2 /24 hr) Mtx (HDMtx) courses. The protocol includes recommendations for CPDG2 administration in cases of DME (clinicaltrials.gov NCT01305655). RESULTS: Forty-seven of the 1,286 children (3.6%) received CPDG2 during 50 HDMtx courses at a median dose of 50 IU/kg. In 49% of the cases, CPDG2 was used during the first HDMtx course. Within a median of 6 hr from CPDG2 administration, the Mtx concentration decreased by 75% when measured with immune-based methods, and by 100% when measured with high-performance liquid chromatography. The median time from the start of Mtx infusion to plasma levels ≤ 0.2 µM was 228 hr (range: 48-438). The maximum increase in plasma creatinine was 375% (range: 100-1,310). Creatinine peaked after a median of 48 hr (range: 36-86). Mtx elimination time was shorter in patients with body surface area < 1 m2 (median 198.5 vs. 257 hr; P = 0.004) and was inversely correlated to the maximum creatinine increase (209 vs. 258 hr; P = 0.034). All patients normalized their renal function as measured with s-creatinine. CONCLUSIONS: CPDG2 administration is highly effective as rescue in case of delayed Mtx clearance. Subsequent HDMtx courses could be administered without events in most of the patients.

Toxicity profile and treatment delays in NOPHO ALL2008-comparing adults and children with Philadelphia chromosome-negative acute lymphoblastic leukemia.

OBJECTIVES: Cure rates improve when adolescents and young adults with acute lymphoblastic leukemia (ALL) are treated according to pediatric protocols. Assumed risks of toxicities and associated delays in treatment have played a role in setting upper age limits. The aim of this study was to examine the toxicity profile and treatment delays in NOPHO ALL2008 comparing children and adults. METHODS: We collected information on 19 treatment-related toxicities, systematically captured at 3-month intervals throughout therapy, and time intervals between 12 consecutive treatment phases for 1076 patients aged 1-45 yrs treated according to the Nordic/Baltic ALL2008 protocol. RESULTS: No adults died during induction. The duration of induction therapy and postinduction treatment phases did not differ between children and adults, except for patients 18-45 yrs being significantly delayed during two of nine high-risk blocks (median number of days for patients 1-9, 10-17, and 18-45 yrs; the glucocorticosteroid/antimetabolite-based block B1: 24, 26, and 29 d, respectively, P = 0.001, and Block 5 (in most cases also a B block): 29, 29, and 37 d, respectively, P = 0.02). A higher incidence of thrombosis with increasing age was found; highest odds ratio 5.4 (95% CI: (2.6;11.0)) for patients 15-17 yrs compared with children 1-9 yrs (P < 0.0001). Risk of avascular osteonecrosis was related to age with the highest OR for patients 10-14 yrs (OR = 10.4 (95% CI: (4.4;24.9)), P < 0.0001). CONCLUSION: Adults followed and tolerated the NOPHO ALL2008 protocol virtually as well as children, although thrombosis and avascular osteonecrosis was most common among adolescents.

DNA Methylation Adds Prognostic Value to Minimal Residual Disease Status in Pediatric T-Cell Acute Lymphoblastic Leukemia.

BACKGROUND: Despite increased knowledge about genetic aberrations in pediatric T-cell acute lymphoblastic leukemia (T-ALL), no clinically feasible treatment-stratifying marker exists at diagnosis. Instead patients are enrolled in intensive induction therapies with substantial side effects. In modern protocols, therapy response is monitored by minimal residual disease (MRD) analysis and used for postinduction risk group stratification. DNA methylation profiling is a candidate for subtype discrimination at diagnosis and we investigated its role as a prognostic marker in pediatric T-ALL. PROCEDURE: Sixty-five diagnostic T-ALL samples from Nordic pediatric patients treated according to the Nordic Society of Pediatric Hematology and Oncology ALL 2008 (NOPHO ALL 2008) protocol were analyzed by HumMeth450K genome wide DNA methylation arrays. Methylation status was analyzed in relation to clinical data and early T-cell precursor (ETP) phenotype. RESULTS: Two distinct CpG island methylator phenotype (CIMP) groups were identified. Patients with a CIMP-negative profile had an inferior response to treatment compared to CIMP-positive patients (3-year cumulative incidence of relapse (CIR3y ) rate: 29% vs. 6%, P = 0.01). Most importantly, CIMP classification at diagnosis allowed subgrouping of high-risk T-ALL patients (MRD ≥0.1% at day 29) into two groups with significant differences in outcome (CIR3y rates: CIMP negative 50% vs. CIMP positive 12%; P = 0.02). These groups did not differ regarding ETP phenotype, but the CIMP-negative group was younger (P = 0.02) and had higher white blood cell count at diagnosis (P = 0.004) compared with the CIMP-positive group. CONCLUSIONS: CIMP classification at diagnosis in combination with MRD during induction therapy is a strong candidate for further risk classification and could confer important information in treatment decision making.

Parents' and Adolescents' Preferences for Intensified or Reduced Treatment in Randomized Lymphoblastic Leukemia Trials.

BACKGROUND: When offered participation in clinical trials, families of children with cancer face a delicate balance between cure and toxicity. Since parents and children may perceive this balance differently, this paper explores whether adolescent patients have different enrollment patterns compared to younger children in trials with different toxicity profiles. PROCEDURE: Age-dependent participation rates in three consecutive, randomized childhood leukemia trials conducted by the Nordic Society of Paediatric Haematology and Oncology were evaluated. The ALL2000 dexamethasone/vincristine (Dx/VCR) trial tested treatment intensifications to improve cure, and the back-to-back ALL2008 6-mercaptopurine (6MP) and ALL2008 PEG-asparaginase (ASP) trials tested treatment intensifications (6MP) and toxicity reduction without compromising survival (ASP). Patient randomization and toxicity data were prospectively registered by the treating physicians. RESULTS: Parents of young children favored treatment intensifications (Dx/VCR: 12% refusal; 6MP: 14%; ASP: 21%), whereas parents of adolescents favored treatment reductions (Dx/VCR: 52% refusal; 6MP: 30%; ASP: 8%). Adolescents were more likely to refuse intensification trials than young children (adjusted ORs 6.3; P < 0.01 [Dx/VCR] and 2.1; P = 0.04 [6MP]). Adolescents were less likely to refuse the ASP trial, with varying effect size depending on the length of the preceding consolidation treatment (adjusted OR for median consolidation length 0.15; P = 0.01). Younger children participated more frequently in only 6MP than in only ASP (14% vs. 5%), and adolescents vice versa (2% vs. 17%; P = 0.001). CONCLUSIONS: Parents' and adolescents' divergent inclinations toward intensified or reduced therapy emphasize the necessity of actively involving adolescents in the informed consent process, which should also address motives for trial participation.

Efficacy and Toxicity of Intrathecal Liposomal Cytarabine in First-line Therapy of Childhood Acute Lymphoblastic Leukemia.

We investigated efficacy and toxicity of replacing conventional triple (cytarabine, methotrexate, and hydrocortisone) intrathecal therapy (TIT) with liposomal cytarabine during maintenance therapy among 40 acute lymphoblastic leukemia patients. Twenty-eight of 29 patients in the TIT arm received TIT and 9/11 in the liposomal cytarabine arm received liposomal cytarabine. Arachnoiditis occurred in all initial 5 patients given liposomal cytarabine and intrathecal prednisolone succinate. Subsequently liposomal cytarabine was given with systemic dexamethasone. Neurotoxicity occurred at 6/27 liposomal cytarabine administrations with concomitant dexamethasone (22%). More liposomal cytarabine-treated patients experienced neurotoxicity in relation to intrathecal therapy during at least 1 cycle compared with TIT-treated patients (6/9 [67%] vs. 3/28 [11%], P=0.002). Apart from intermittent lower extremity sensory pain in 1 liposomal cytarabine-treated patient, no permanent adverse neurological sequelae were observed. In intention-to-treat analysis, projected 5-year event-free survival (pEFS-5y) was borderline higher for patients in the liposomal cytarabine arm compared with the TIT arm (1.0 vs. 0.69, P=0.046). However, pEFS-5y and projected 5-year relapse-free survival did not differ signficantly between patients treated with liposomal cytarabine or TIT (1.0 vs. 0.73, P=0.10; 1.0 vs. 0.76, P=0.12). Larger prospective trials are needed to explore whether liposomal cytarabine should be used as first-line prevention of relapse.

Lower hemoglobin with lower ferritin - results from the HUNT 2 Study.

AIM: We wanted to study the association between blood hemoglobin concentration (b-hemoglobin) and serum ferritin concentration (s-ferritin) in a healthy female population, and compare the findings to those in a previous study of ambulant female patients. METHODS: We compared median b-hemoglobin and the fraction with anemia in groups of women with s-ferritin from less than 10 µg/L to 100 µg/L. These women, aged 20-55 years, were part of a health screening survey (HUNT 2) where they reported to have 'good' or 'very good' general health and were found to have normal s-creatinine. The s-ferritin values were adjusted to the level of the previous study. The 10, 50 and 90 percentiles of b-hemoglobin were modelled as functions of s-ferritin using quantile regression. RESULTS: Among 2122 healthy females the entire b-hemoglobin distribution was shifted downwards in women with s-ferritin less than 20 µg/L. Accordingly, the median b-hemoglobin was statistically significantly lower. In women with s-ferritin less than 20 µg/L the fraction with anemia was 0.15. CONCLUSIONS: Lower s-ferritin is associated with lower b-hemoglobin in many more subjects than those labelled anemic.

Clinical features and early treatment response of central nervous system involvement in childhood acute lymphoblastic leukemia.

BACKGROUND: Central nervous system (CNS) involvement in childhood acute lymphoblastic leukemia (ALL) remains a therapeutic challenge. PROCEDURE: To explore leukemia characteristics of patients with CNS involvement at ALL diagnosis, we analyzed clinical features and early treatment response of 744 patients on Nordic-Baltic trials. CNS status was classified as CNS1 (no CSF blasts), CNS2 (<5 leukocytes/µl CSF with blasts), CNS3 (≥5 leukocytes/µl with blasts or signs of CNS involvement), TLP+ (traumatic lumbar puncture with blasts), and TLP- (TLP with no blasts). RESULTS: Patients with CNS involvement had higher leukocyte count compared with patients with CNS1 (P < 0.002). Patients with CNS3 more often had T-ALL (P < 0.001) and t(9;22)(q34;q11)[BCR-ABL1] (P < 0.004) compared with patients with CNS1. Among patients with CNS involvement headache (17%) and vomiting (14%) were most common symptoms. Symptoms or clinical findings were present among 27 of 54 patients with CNS3 versus only 7 of 39 patients with CNS2 and 15 of 75 patients with TLP+ (P < 0.001). The majority of patients with CNS involvement received additional induction therapy. The post induction bone marrow residual disease level did not differ between patients with CNS involvement and patients with CNS1 (P > 0.15). The 12-year event-free survival for patients with leukemic mass on neuroimaging did not differ from patients with negative or no scan (0.50 vs. 0.60; P = 0.7) or between patients with symptoms or signs suggestive of CNS leukemia and patients without such characteristics (0.50 vs. 0.61; P = 0.2). CONCLUSION: CNS involvement at diagnosis is associated with adverse prognostic features but does not indicate a less chemosensitive leukemia.

Risk group assignment differs for children and adults 1-45 yr with acute lymphoblastic leukemia treated by the NOPHO ALL-2008 protocol.

BACKGROUND: The prognosis of acute lymphoblastic leukemia is poorer in adults than in children. Studies have indicated that young adults benefit from pediatric treatment, although no upper age limit has been defined. DESIGN AND METHODS: We analyzed 749 patients aged 1-45 yr treated by the NOPHO ALL-2008 protocol. Minimal residual disease (MRD) on days 29 and 79, immunophenotype, white blood cell count (WBC), and cytogenetics were used to stratify patients to standard-, intermediate-, or high-risk treatment with or without hematopoietic stem cell transplantation. RESULTS: Adults aged 18-45 had significantly lower WBCs at diagnosis compared with children aged 1-9 and 10-17 yr, but significantly more adults were stratified to high-risk chemotherapy (8%, 14%, 17%; P < 0.0001) or high-risk chemotherapy with transplantation (4%, 13%, 19%; P < 0.0001). This age-dependent skewing of risk grouping reflected more T-ALL (11%, 27%, 33%, P < 0.0001), poorer MRD response day 29 (MRD < 0.1%: 75%, 61%, 52%; P < 0.0001), and more MLL gene rearrangements (3%, 3%, 10%; P = 0.005) in older patients. CONCLUSIONS: Even if identical diagnostics, treatment, and risk stratification are implemented, more adults will be stratified to high-risk therapy, which should be considered when comparing pediatric and adult outcomes.

Lower hemoglobin with lower ferritin: It is not just a question of anemia.

AIM: To study the association between blood hemoglobin concentration (b-hemoglobin) and serum ferritin concentration (s-ferritin) in an ambulant patient population without inflammation and with normal kidney function. METHODS: In ambulant, adult patients with normal values of s-CRP and s-creatinine, median b-hemoglobin and the fraction with anemia was compared in groups with lower s-ferritin from a level of 100 µg/L. The 10, 50 and 90 percentiles of b-hemoglobin were modelled as functions of s-ferritin using quantile regression. RESULTS: Among 3206 women the entire b-hemoglobin distribution was shifted downwards in patients with s-ferritin less than 20 µg/L. Accordingly, the median b-hemoglobin was statistically significantly lower and the fraction with anemia was higher. In 1246 men the findings were similar, except that the turning point toward lower b-hemoglobin was at a s-ferritin level of 30 µg/L. CONCLUSIONS: Low s-ferritin is associated with decreased b-hemoglobin in many more subjects than those labelled anemic.

The diagnostic accuracy of unbound iron binding capacity (UIBC) as a test for empty iron stores.

BACKGROUND: Unbound iron binding capacity (UIBC) in serum, which is s-total iron binding capacity (2 times s- transferrin) minus s-iron, may be a more accurate marker of empty iron stores than serum transferrin saturation. Previously we have shown this for healthy females of childbearing age. METHODS: Now we used receiver operating characteristic (ROC) curve analysis to compare the diagnostic accuracy of s-iron, s-transferrin, s-transferrin saturation and s-UIBC in diagnosing empty iron stores in 29,251 female and 19,652 male outpatients. Empty iron stores were defined as s-ferritin less than 10, 15 or 20 µg/L. RESULTS: At all definitions of empty iron stores s-UIBC had a better diagnostic accuracy than the other tests in both male and female outpatients, with an area under the ROC curve of 0.85-0.97. Also in subpopulations with elevated s-CRP or low b-hemoglobin s-UIBC was more accurate than the other tests. All tests performed better in males than in females, and generally they were more accurate in adults than in children. CONCLUSION: When diagnosing empty iron stores calculation of s-UIBC is a better way to utilize the information in s-iron and s-transferrin than the calculation of s-transferrin saturation.

Risk factors for treatment related mortality in childhood acute lymphoblastic leukaemia.

BACKGROUND: In spite of major improvements in the cure rate of childhood acute lymphoblastic leukaemia (ALL), 2-4% of patients still die from treatment related complications. PROCEDURE: We investigated the pattern of treatment related deaths (TRDs) and possible risk factors in the NOPHO ALL-92 and ALL-2000 protocols. Fifty-five TRDs were identified among the 1,645 ALL-92 patients and 33 among the 1,090 ALL-2000 patients. RESULTS: There was no significant difference in the incidence of TRDs between the two protocols (3.4% vs. 3.2%). Five patients died before initiation of therapy (0.2%), and the overall subsequent risk of induction death and death in first complete remission (CR1) was 1.2% and 1.8%, respectively. Infections were the major cause of death comprising 72% of all cases including 9 deaths from Pseudomonas aeruginosa and 11 deaths from fungal infections. Other causes of death included bleeding or thrombosis (eight patients), tumour burden related toxicities (seven patients) and organ toxicity (seven patients). Female gender (hazard ratio (HR): 2.2, 95% confidence interval (95% CI): 1.4-3.4), high white blood cell count (≥ 200 × 10(9) /L) at diagnosis (HR: 3.5, 95% CI: 1.7-7.1), T-cell disease (HR: 1.9, 95% CI: 1.01-3.7), Down syndrome (HR: 7.3, 95% CI: 3.6-14.9) and haematopoietic stem cell transplantation in CR1 (HR: 8.0, 95% CI: 3.3-19.5) were identified as independent risk factors for TRD. CONCLUSION: Several TRDs were potentially preventable and future efforts should be directed towards patients at risk.

Molecular characterization of the MLL-SEPT6 fusion gene in acute myeloid leukemia: identification of novel fusion transcripts and cloning of genomic breakpoint junctions.

One of the MLL fusion partners in leukemia is the SEPT6 gene, which belongs to the evolutionarily conserved family of genes of septins. In this work we aimed to characterize at both the RNA and DNA levels three acute myeloid leukemias with cytogenetic evidence of a rearrangement between 11q23 and Xq24. Molecular analysis led to the identification of several MLL-SEPT6 fusion transcripts in all cases, including a novel MLL-SEPT6 rearrangement (MLL exon 6 fused with SEPT6 exon 2). Genomic DNA breakpoints were found inside or near Alu or LINE repeats in the MLL breakpoint cluster region, whereas the breakpoint junctions in the SEPT6 intron 1 mapped to the vicinity of GC-rich low-complexity repeats, Alu repeats, and a topoisomerase II consensus cleavage site. These data suggest that a non-homologous end-joining repair mechanism may be involved in the generation of MLL-SEPT6 rearrangements in acute myeloid leukemia.

Neutrophil dysfunction after biomaterial contact in an in vitro model of cardiopulmonary bypass.

OBJECTIVE: Cardiopulmonary bypass (CPB) induces neutrophil degranulation and superoxide anion production in vivo. We hypothesized that CPB-associated neutrophil dysregulation alters neutrophil adhesion to vascular endothelial cells and the extracellular matrix. METHODS: We, therefore, recirculated neutrophils in polyvinyl chloride (PVC) tubing using a roller pump model and thereafter measured adhesion to cultured microvascular endothelial cells and gelatin-coated surfaces. Recirculation-induced neutrophil priming or exhaustion was tested by boosting with phorbol myristate-acetate (PMA) or N-formyl-methiolyl-leucyl-phenylalanine (FMLP) before quantification of adhesion. RESULTS AND CONCLUSION: After recirculation, neutrophils retained their adhesive capability to vascular endothelial cells, whereas adhesion to gelatin increased. This increase was not seen when the neutrophils were recirculated with a rotator instead of a roller pump, indicating that not only the pump mode but also foreign surface contact was of significance. The neutrophil PMA response after recirculation was not altered compared to resting neutrophils prestimulated with PMA. Recirculated neutrophils adhered less to cultured vascular endothelial cells after FMLP activation and more to gelatin compared to resting neutrophils prestimulated with FMLP. It is conceivable that dysregulation of neutrophil adhesive capability may play a part in the development of tissue damage after CPB.

Complying with the European Clinical Trials directive while surviving the administrative pressure - an alternative approach to toxicity registration in a cancer trial.

The European Clinical Trials Directive of 2004 has increased the amount of paper work and reduced the number of initiated clinical trials. Particularly multinational trials have been delayed. To meet this challenge we developed a novel, simplified, fast and easy strategy for on-line toxicity registration for patients treated according to the Nordic/Baltic acute lymphoblastic leukaemia protocol, NOPHO ALL 2008, for children and young adults, including three randomisations. We used a risk-assessment based approach, avoiding reporting of expected adverse events and instead concentrating on 20 well-known serious, but rarer events with focus on changes in therapy introduced in the treatment protocol. This toxicity registration strategy was approved by the relevant regulatory authorities in all seven countries involved, as compliant within the EU directive of 2004. The centre compliance to registration was excellent with 98.9% of all patients being registered within 5weeks from the requested quarterly registration. Currently, four toxicities (thrombosis, fungal infections, pancreatitis and allergic reactions) have been chosen for further detailed exploration due to the cumulative fraction of patients with positive registrations exceeding 5%. This toxicity registration offers real-time toxicity profiles of the total study cohort and provides early warnings of specific toxicities that require further investigation.

Inhibition of platelet receptors involved in neutrophil-platelet interaction in model cardiopulmonary bypass.

We investigated the interactions between neutrophils, platelets, and artificial surfaces, and whether blocking of relevant receptors on platelets reduced unwanted activation responses in model cardiopulmonary bypass. Isolated neutrophils and platelets resuspended in heparin-anticoagulated plasma were recirculated with and without blocking antibodies to CD62P, CD42b, or junctional adhesion molecule C (JAM-C) in polyvinyl chloride tubing using a roller pump. Platelet adhesion to the tubing was inhibited by anti-CD42b and anti-CD62P, and adhesion of neutrophils by anti-JAM-C. Formation of platelet-neutrophil and platelet aggregates was reduced by anti-CD62P. Anti-JAM-C decreased platelet-neutrophil aggregation at low concentrations and platelet macroaggregates at high concentrations. Anti-CD62P increased neutrophil CD11b expression but not degranulation. Anti-JAM-C substantially increased neutrophil degranulation and slightly increased CD11b expression. Platelet activation increased when CD62P was blocked and decreased with anti-CD42b antibody. High-dose anti-JAM-C reduced platelet activation. In conclusion, inhibiting platelet and neutrophil-platelet interactions had useful effects but no single blocking antibody seemed capable of inducing only beneficial effects.

Concentration-dependent effect of abciximab on platelets and neutrophils in a model of cardiopulmonary bypass.

Abciximab is a GPIIb/IIIa antagonist used in percutaneous coronary interventions to avoid platelet activation, thrombosis and inflammation. We investigated whether abciximab influenced platelet activation and platelet interaction with neutrophils and polyvinyl chloride (PVC) in a cardiopulmonary bypass (CPB) model. Isolated platelets, preincubated with and without 0.1-20 microg/mL of abciximab, were resuspended with neutrophils in plasma and recirculated by a roller pump. Platelet, but not neutrophil adhesion to PVC was inhibited by abciximab. Only high doses of abciximab reduced platelet aggregation size, but simultaneously increased platelet-neutrophil aggregation. Abciximab had no effect on platelet CD62P expression or degranulation, but platelet activation on platelet-neutrophil aggregates increased with high doses. Only low doses inhibited neutrophil degranulation. The concentration-dependent effect of abciximab on platelet-neutrophil interaction reduces its usefulness and stresses the dependency on experimental design in the evaluation of abciximab. Our study does not support the use of abciximab alone in CPB. However, incorporation of surface-coating the biomaterial with abciximab may be an interesting option.

Activation of neutrophil granulocytes in an in vitro model of a cardiopulmonary bypass.

Activated neutrophils play a central role in the pathogenesis of postoperative organ dysfunction after surgery with cardiopulmonary bypass. The researchers used an in vitro roller pump model to investigate the relative importance of the biomaterial, platelets, plasma proteins including activated complement, and flow mode on neutrophil activation as shown by the adhesion, degranulation, and increased the surface expression of CD11b. Neutrophil adhesion to the biomaterial increased with platelet addition, but not with plasma. Biomaterial contact activated neutrophils in a serum-free buffer, but was significantly increased by activated complement. Platelets increased neutrophil degranulation in a serum-free buffer but tended to reduce it in plasma. CD11b expression increased in both media. Complement activation was higher with neutrophils alone than with neutrophils and platelets combined. The roller pump reduced neutrophil adhesion and increased degranulation compared to passive rotation. Neutrophil interaction with platelets and complement were more important for activation than biomaterial contact and use of the roller pump. Improvement of biocompatibility is dependent on modifying complement activation and platelet interaction with neutrophils.