Ronald Malfait - Academia.edu (original) (raw)

Papers by Ronald Malfait

Research paper thumbnail of Sampling Site Matters When Counting Lymphocyte Subpopulations

PLoS ONE, 2012

Clinical and scientific work routinely relies on antecubital venipunctures for hematological, imm... more Clinical and scientific work routinely relies on antecubital venipunctures for hematological, immunological or other analyses on blood. This study tested the hypothesis that antecubital veins can be considered to be a good proxy for other sampling sites. Using a hematocytometer and a flow cytometer, we analyzed the cell counts from samples coming from the radial artery, the dorsal hand veins and the antecubital veins from 18 volunteers. Most surprisingly, we identified the greatest difference not to exist between arterial and venous circulation, but between the distal (radial artery & dorsal hand veins) and proximal (antecubital veins) sampling sites. Naïve T cells had a higher cell count distally compared to proximally and the reverse was true for effector memory T cells. Despite these differences there were high correlations between the different sampling sites, which partially supports our initial hypothesis. Our findings are crucial for the future design and interpretation of immunological research, and for clinical practice. Furthermore, our results suggest a role for interval lymph nodes in the trafficking of lymphocytes.

Research paper thumbnail of Performance evaluation of the Sysmex XS-1000 i automated haematology analyser

Int J Lab Hematol, 2009

Automated haematology analysers generate a complete blood count and five-part differential leucoc... more Automated haematology analysers generate a complete blood count and five-part differential leucocyte count (CBC 5-diff) with a rapid turn around time. The Sysmex XS-1000i is a new, fully automated haematology analyser with 5-diff functionality. In our study, a Sysmex XS-1000i with auto-sampler was evaluated according to Clinical Laboratory Standards Institute (CLSI) and International Council for Standardization in Haematology (ICSH) guidelines. The purpose of our study was to evaluate performance characteristics of the Sysmex Evaluation of the instrument was carried out using K 2 EDTA (1.2-2 mg/mL blood; Sarstedt, Essen, Belgium) anticoagulated venous blood samples sent to our NPV, % (CI) 87 (78-94) PPV, % (CI) 56 (51-59) Efficiency, % (CI) 66 (60-70) CI, 95% confidence interval; NPV, negative predicitive value; PPV, positive predictive value.

Research paper thumbnail of Prevention Of Relapse In Acute Myeloid Leukemia By Dendritic Cell Vaccination: Report on a Phase II Study With 29 Patients

Research paper thumbnail of Sampling Site Matters When Counting Lymphocyte Subpopulations

PLoS ONE, 2012

Clinical and scientific work routinely relies on antecubital venipunctures for hematological, imm... more Clinical and scientific work routinely relies on antecubital venipunctures for hematological, immunological or other analyses on blood. This study tested the hypothesis that antecubital veins can be considered to be a good proxy for other sampling sites. Using a hematocytometer and a flow cytometer, we analyzed the cell counts from samples coming from the radial artery, the dorsal hand veins and the antecubital veins from 18 volunteers. Most surprisingly, we identified the greatest difference not to exist between arterial and venous circulation, but between the distal (radial artery & dorsal hand veins) and proximal (antecubital veins) sampling sites. Naïve T cells had a higher cell count distally compared to proximally and the reverse was true for effector memory T cells. Despite these differences there were high correlations between the different sampling sites, which partially supports our initial hypothesis. Our findings are crucial for the future design and interpretation of immunological research, and for clinical practice. Furthermore, our results suggest a role for interval lymph nodes in the trafficking of lymphocytes.

Research paper thumbnail of Creating a robust framework for the analysis of cryopreserved samples in quantitative immunological experiments

Journal of Immunological Methods, 2013

Longitudinal clinical or experimental immunological studies warrant the use of cryopreserved samp... more Longitudinal clinical or experimental immunological studies warrant the use of cryopreserved samples for flow cytometric phenotyping. Most notably CD62L+ and CD25+Foxp3+ counts were shown to be reduced by past studies. Here we are the first to compare the effects of cryopreservation on cell type calculations performed on a longitudinal dataset. We first compared lymphocyte subpopulation counts from fresh samples with those from samples frozen for either 5 or 6 months coming from 9 individuals. This way, we found that the cell counts obtained after basic lymphocyte differentiation in CD3+CD4+, CD3+CD8+, CD3-CD19+ and CD3-CD56+ were relatively robust for cryopreservation. However, when further subtyping CD4+ and CD8+ cells, we only found CCR7 and CD45RA to have a relation between fresh and cryopreserved counts, but we could not conclude the same for CD62L. Also, CD4+CD25+Foxp3+ were shown to be approximately 0.5 times less counted after cryopreservation. Next, we performed basic longitudinal calculations for which we either subtracted the cell counts at time 1 from the cell counts at time 2 or calculated the ratio between the cell counts at time 2 and time 1, for both fresh and cryopreserved samples. This way, we found that the use of absolute cell counts supported a good one-to-one relation between fresh and cryopreserved counts for all markers except CD62L and CD4+CD25+Foxp3+. In conclusion, we found no support for the use of CD62L and CD4+CD25+Foxp3+ as markers for calculations on flow cytometric counts from cryopreserved longitudinal datasets. However, all other basic lymphocyte markers proved to be relatively robust if absolute counts were used.

Research paper thumbnail of Performance evaluation of the Sysmex XS-1000 i automated haematology analyser

International Journal of Laboratory Hematology, 2009

Automated haematology analysers generate a complete blood count and five-part differential leucoc... more Automated haematology analysers generate a complete blood count and five-part differential leucocyte count (CBC 5-diff) with a rapid turn around time. The Sysmex XS-1000i is a new, fully automated haematology analyser with 5-diff functionality. In our study, a Sysmex XS-1000i with auto-sampler was evaluated according to Clinical Laboratory Standards Institute (CLSI) and International Council for Standardization in Haematology (ICSH) guidelines. The purpose of our study was to evaluate performance characteristics of the Sysmex Evaluation of the instrument was carried out using K 2 EDTA (1.2-2 mg/mL blood; Sarstedt, Essen, Belgium) anticoagulated venous blood samples sent to our NPV, % (CI) 87 (78-94) PPV, % (CI) 56 (51-59) Efficiency, % (CI) 66 (60-70) CI, 95% confidence interval; NPV, negative predicitive value; PPV, positive predictive value.

Research paper thumbnail of Comparison of the reticulocyte mode of the Abx Pentra 120 Retic, CoulterR General-Stm, SysmexR SE 9500, Abbott CD 4000 and Bayer AdviaR 120 haematology analysers in a simultaneous evaluation

Clinical and Laboratory Haematology, 2001

The Abx Pentra 120 Retic, Coulter Ò General-SÔ, Sysmex Ò SE 9500, Abbott Cell Dyn Ò 4000 and Baye... more The Abx Pentra 120 Retic, Coulter Ò General-SÔ, Sysmex Ò SE 9500, Abbott Cell Dyn Ò 4000 and Bayer Advia Ò 120 were evaluated simultaneously in a general hospital laboratory. Linearity, precision, sample stability, carry-over and comparability of the reticulocyte mode were determined following International Council for Standardization in Haematology guidelines for the evaluation of blood cell analysers. All analysers showed good results for dilution, stability and carry-over testing. The between-batch coef®cient of variation of the General-SÔ was high compared to the other analysers evaluated. Multiple correlation studies showed good agreement for all analysers in the normal and high reticulocyte range, with correlation coef®cients above 0.7. Multiple correlation studies for reticulocytopenic samples (< 15.10 9 /l) were less satisfactory, with a wider range of correlation coef®cients (r-values 0.0±0.9). Overall, the General-SÔ, SE 9500 and Advia Ò 120 gave lower reticulocyte counts than the Pentra 120 Retic and CD 4000. Reagent costs were also evaluated. Reagent consumption was close to the manufacturers' speci®cations for the SE 9500 (Search reagent), CD 4000 (CD Retic) and Advia Ò 120 (Retics) but was higher than stated for the Pentra 120 Retic (Retix), General-SÔ (Retic kit) and SE 9500 (Sheath reagent). Our results show that these new generation haematology analysers will meet the needs of hospital laboratories for reliable and cost-effective reticulocyte counting.

Research paper thumbnail of Reference Intervals for a Complete Blood Count Determined on different Automated Haematology Analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120

Clinical Chemistry and Laboratory Medicine, 2000

We processed 317 samples from healthy adult volunteers for a complete blood count, including leuk... more We processed 317 samples from healthy adult volunteers for a complete blood count, including leukocyte differentials and reticulocyte parameters, through five new-generation haematology analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120. From these data nonparametric 2.5-97.5 percentile reference intervals were calculated for all parameters on all analysers. Some differences were found compared with previously reported reference intervals. Reference intervals for platelet parameters and reticulocytes agreed with these usually accepted. For red blood cell parameters, including haemoglobin and haematocrit, and white blood cell count, including absolute white blood cell differentials, our calculated reference intervals were in agreement with less frequently cited earlier reports, but were lower compared to the usually accepted reference intervals. Clin Chem Lab Med 2002; 40(1): 69-73

Research paper thumbnail of Factor V inhibitor: case report

Blood Coagulation & Fibrinolysis, 2006

Acquired inhibitors to coagulation factors are rare, certainly those directed against factor V. A... more Acquired inhibitors to coagulation factors are rare, certainly those directed against factor V. A total of around 150 cases have so far been reported, of which the greater part was due to bovine thrombin exposure. We report the case of a patient who developed a factor V inhibitor during a postoperative period. This report describes possible aetiologies, varying clinical conditions and treatment possibilities as described in the literature. Furthermore, this case report is an example of the often unpredictable disease progression in a patient with existence of a factor V inhibitor.

Research paper thumbnail of Influence of Frequent Infectious Exposures on General and Varicella-Zoster Virus-Specific Immune Responses in Pediatricians

Clinical and Vaccine Immunology, 2014

Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary im... more Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary immune response. We studied the effects of frequent exposure to viral infectious challenges on immunity. Furthermore, we assessed whether repetitive exposures to varicella-zoster virus (VZV) elicited persistently high immune responses. Blood samples from 11 pediatricians and matched controls were assessed at 3 time points and 1 time point, respectively.

Research paper thumbnail of Sampling Site Matters When Counting Lymphocyte Subpopulations

PLoS ONE, 2012

Clinical and scientific work routinely relies on antecubital venipunctures for hematological, imm... more Clinical and scientific work routinely relies on antecubital venipunctures for hematological, immunological or other analyses on blood. This study tested the hypothesis that antecubital veins can be considered to be a good proxy for other sampling sites. Using a hematocytometer and a flow cytometer, we analyzed the cell counts from samples coming from the radial artery, the dorsal hand veins and the antecubital veins from 18 volunteers. Most surprisingly, we identified the greatest difference not to exist between arterial and venous circulation, but between the distal (radial artery & dorsal hand veins) and proximal (antecubital veins) sampling sites. Naïve T cells had a higher cell count distally compared to proximally and the reverse was true for effector memory T cells. Despite these differences there were high correlations between the different sampling sites, which partially supports our initial hypothesis. Our findings are crucial for the future design and interpretation of immunological research, and for clinical practice. Furthermore, our results suggest a role for interval lymph nodes in the trafficking of lymphocytes.

Research paper thumbnail of Performance evaluation of the Sysmex XS-1000 i automated haematology analyser

Int J Lab Hematol, 2009

Automated haematology analysers generate a complete blood count and five-part differential leucoc... more Automated haematology analysers generate a complete blood count and five-part differential leucocyte count (CBC 5-diff) with a rapid turn around time. The Sysmex XS-1000i is a new, fully automated haematology analyser with 5-diff functionality. In our study, a Sysmex XS-1000i with auto-sampler was evaluated according to Clinical Laboratory Standards Institute (CLSI) and International Council for Standardization in Haematology (ICSH) guidelines. The purpose of our study was to evaluate performance characteristics of the Sysmex Evaluation of the instrument was carried out using K 2 EDTA (1.2-2 mg/mL blood; Sarstedt, Essen, Belgium) anticoagulated venous blood samples sent to our NPV, % (CI) 87 (78-94) PPV, % (CI) 56 (51-59) Efficiency, % (CI) 66 (60-70) CI, 95% confidence interval; NPV, negative predicitive value; PPV, positive predictive value.

Research paper thumbnail of Prevention Of Relapse In Acute Myeloid Leukemia By Dendritic Cell Vaccination: Report on a Phase II Study With 29 Patients

Research paper thumbnail of Sampling Site Matters When Counting Lymphocyte Subpopulations

PLoS ONE, 2012

Clinical and scientific work routinely relies on antecubital venipunctures for hematological, imm... more Clinical and scientific work routinely relies on antecubital venipunctures for hematological, immunological or other analyses on blood. This study tested the hypothesis that antecubital veins can be considered to be a good proxy for other sampling sites. Using a hematocytometer and a flow cytometer, we analyzed the cell counts from samples coming from the radial artery, the dorsal hand veins and the antecubital veins from 18 volunteers. Most surprisingly, we identified the greatest difference not to exist between arterial and venous circulation, but between the distal (radial artery & dorsal hand veins) and proximal (antecubital veins) sampling sites. Naïve T cells had a higher cell count distally compared to proximally and the reverse was true for effector memory T cells. Despite these differences there were high correlations between the different sampling sites, which partially supports our initial hypothesis. Our findings are crucial for the future design and interpretation of immunological research, and for clinical practice. Furthermore, our results suggest a role for interval lymph nodes in the trafficking of lymphocytes.

Research paper thumbnail of Creating a robust framework for the analysis of cryopreserved samples in quantitative immunological experiments

Journal of Immunological Methods, 2013

Longitudinal clinical or experimental immunological studies warrant the use of cryopreserved samp... more Longitudinal clinical or experimental immunological studies warrant the use of cryopreserved samples for flow cytometric phenotyping. Most notably CD62L+ and CD25+Foxp3+ counts were shown to be reduced by past studies. Here we are the first to compare the effects of cryopreservation on cell type calculations performed on a longitudinal dataset. We first compared lymphocyte subpopulation counts from fresh samples with those from samples frozen for either 5 or 6 months coming from 9 individuals. This way, we found that the cell counts obtained after basic lymphocyte differentiation in CD3+CD4+, CD3+CD8+, CD3-CD19+ and CD3-CD56+ were relatively robust for cryopreservation. However, when further subtyping CD4+ and CD8+ cells, we only found CCR7 and CD45RA to have a relation between fresh and cryopreserved counts, but we could not conclude the same for CD62L. Also, CD4+CD25+Foxp3+ were shown to be approximately 0.5 times less counted after cryopreservation. Next, we performed basic longitudinal calculations for which we either subtracted the cell counts at time 1 from the cell counts at time 2 or calculated the ratio between the cell counts at time 2 and time 1, for both fresh and cryopreserved samples. This way, we found that the use of absolute cell counts supported a good one-to-one relation between fresh and cryopreserved counts for all markers except CD62L and CD4+CD25+Foxp3+. In conclusion, we found no support for the use of CD62L and CD4+CD25+Foxp3+ as markers for calculations on flow cytometric counts from cryopreserved longitudinal datasets. However, all other basic lymphocyte markers proved to be relatively robust if absolute counts were used.

Research paper thumbnail of Performance evaluation of the Sysmex XS-1000 i automated haematology analyser

International Journal of Laboratory Hematology, 2009

Automated haematology analysers generate a complete blood count and five-part differential leucoc... more Automated haematology analysers generate a complete blood count and five-part differential leucocyte count (CBC 5-diff) with a rapid turn around time. The Sysmex XS-1000i is a new, fully automated haematology analyser with 5-diff functionality. In our study, a Sysmex XS-1000i with auto-sampler was evaluated according to Clinical Laboratory Standards Institute (CLSI) and International Council for Standardization in Haematology (ICSH) guidelines. The purpose of our study was to evaluate performance characteristics of the Sysmex Evaluation of the instrument was carried out using K 2 EDTA (1.2-2 mg/mL blood; Sarstedt, Essen, Belgium) anticoagulated venous blood samples sent to our NPV, % (CI) 87 (78-94) PPV, % (CI) 56 (51-59) Efficiency, % (CI) 66 (60-70) CI, 95% confidence interval; NPV, negative predicitive value; PPV, positive predictive value.

Research paper thumbnail of Comparison of the reticulocyte mode of the Abx Pentra 120 Retic, CoulterR General-Stm, SysmexR SE 9500, Abbott CD 4000 and Bayer AdviaR 120 haematology analysers in a simultaneous evaluation

Clinical and Laboratory Haematology, 2001

The Abx Pentra 120 Retic, Coulter Ò General-SÔ, Sysmex Ò SE 9500, Abbott Cell Dyn Ò 4000 and Baye... more The Abx Pentra 120 Retic, Coulter Ò General-SÔ, Sysmex Ò SE 9500, Abbott Cell Dyn Ò 4000 and Bayer Advia Ò 120 were evaluated simultaneously in a general hospital laboratory. Linearity, precision, sample stability, carry-over and comparability of the reticulocyte mode were determined following International Council for Standardization in Haematology guidelines for the evaluation of blood cell analysers. All analysers showed good results for dilution, stability and carry-over testing. The between-batch coef®cient of variation of the General-SÔ was high compared to the other analysers evaluated. Multiple correlation studies showed good agreement for all analysers in the normal and high reticulocyte range, with correlation coef®cients above 0.7. Multiple correlation studies for reticulocytopenic samples (< 15.10 9 /l) were less satisfactory, with a wider range of correlation coef®cients (r-values 0.0±0.9). Overall, the General-SÔ, SE 9500 and Advia Ò 120 gave lower reticulocyte counts than the Pentra 120 Retic and CD 4000. Reagent costs were also evaluated. Reagent consumption was close to the manufacturers' speci®cations for the SE 9500 (Search reagent), CD 4000 (CD Retic) and Advia Ò 120 (Retics) but was higher than stated for the Pentra 120 Retic (Retix), General-SÔ (Retic kit) and SE 9500 (Sheath reagent). Our results show that these new generation haematology analysers will meet the needs of hospital laboratories for reliable and cost-effective reticulocyte counting.

Research paper thumbnail of Reference Intervals for a Complete Blood Count Determined on different Automated Haematology Analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120

Clinical Chemistry and Laboratory Medicine, 2000

We processed 317 samples from healthy adult volunteers for a complete blood count, including leuk... more We processed 317 samples from healthy adult volunteers for a complete blood count, including leukocyte differentials and reticulocyte parameters, through five new-generation haematology analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120. From these data nonparametric 2.5-97.5 percentile reference intervals were calculated for all parameters on all analysers. Some differences were found compared with previously reported reference intervals. Reference intervals for platelet parameters and reticulocytes agreed with these usually accepted. For red blood cell parameters, including haemoglobin and haematocrit, and white blood cell count, including absolute white blood cell differentials, our calculated reference intervals were in agreement with less frequently cited earlier reports, but were lower compared to the usually accepted reference intervals. Clin Chem Lab Med 2002; 40(1): 69-73

Research paper thumbnail of Factor V inhibitor: case report

Blood Coagulation & Fibrinolysis, 2006

Acquired inhibitors to coagulation factors are rare, certainly those directed against factor V. A... more Acquired inhibitors to coagulation factors are rare, certainly those directed against factor V. A total of around 150 cases have so far been reported, of which the greater part was due to bovine thrombin exposure. We report the case of a patient who developed a factor V inhibitor during a postoperative period. This report describes possible aetiologies, varying clinical conditions and treatment possibilities as described in the literature. Furthermore, this case report is an example of the often unpredictable disease progression in a patient with existence of a factor V inhibitor.

Research paper thumbnail of Influence of Frequent Infectious Exposures on General and Varicella-Zoster Virus-Specific Immune Responses in Pediatricians

Clinical and Vaccine Immunology, 2014

Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary im... more Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary immune response. We studied the effects of frequent exposure to viral infectious challenges on immunity. Furthermore, we assessed whether repetitive exposures to varicella-zoster virus (VZV) elicited persistently high immune responses. Blood samples from 11 pediatricians and matched controls were assessed at 3 time points and 1 time point, respectively.