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Zhang X, Lumen A, Wong H, Connarn J, Dutta S, Upreti VV. A Mechanistic Physiologically-Based Pharmacokinetic Platform Model to Guide Adult and Pediatric Intravenous and Subcutaneous Dosing for Bispecific T Cell Engagers. Clin Pharmacol Ther 2024; 115:457-467. [PMID: 37746860 DOI: 10.1002/cpt.3056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/11/2023] [Indexed: 09/26/2023]
Abstract
Bispecific T cell engagers (Bi-TCEs) have revolutionized the treatment of oncology indications across both liquid and solid tumors. Bi-TCEs are rapidly evolving from conventional intravenous (i.v.) to more convenient subcutaneous (s.c.) administrations and extending beyond adults to also benefit pediatric patients. Leveraging clinical development experience across three generations of Bi-TCE molecules across both liquid and solid tumor indications from i.v./s.c. dosing in adults and pediatric subjects, we developed a mechanistic-physiologically-based pharmacokinetic (PBPK) platform model for Bi-TCEs. The model utilizes a full PBPK model framework and was successfully validated for PK predictions following i.v. and s.c. dosing across both liquid and solid tumor space in adults for eight Bi-TCEs. After refinement to incorporate physiological ontogeny, the model was successfully validated to predict pediatric PKs in 1 month - < 2 years, 2-11 years, and 12-17 years old subjects following i.v. dosing. Following s.c. dosing in pediatric subjects, the model predicted similar bioavailability, however, a shorter time to maximum concentration (Tmax ) for the three age groups compared with adults. The model was also applied to guide the dosing strategy for first generation of Bi-TCEs for organ impairment, specifically renal impairment, and was able to accurately predict the impact of renal impairment on PK for these relatively small-size Bi-TCEs. This work highlights a novel mechanistic platform model for accurately predicting the PK in adult and pediatric patients across liquid and solid tumor indications from i.v./s.c. dosing and can be used to guide optimal dose and dosing regimen selection and accelerating the clinical development for Bi-TCEs.
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Affiliation(s)
- Xinwen Zhang
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Annie Lumen
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Hansen Wong
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Jamie Connarn
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Sandeep Dutta
- Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - Vijay V Upreti
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
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Stevens CR, Atkuri K, Menard DL, King LE, Neubert H, Goihberg P. Mass cytometry for the multiplexed quantification and characterization of target expression on circulating cells in whole blood. Cytometry A 2023; 103:631-645. [PMID: 36966446 DOI: 10.1002/cyto.a.24730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/09/2023] [Accepted: 03/21/2023] [Indexed: 03/27/2023]
Abstract
Characterization of target abundance on cells has broad translational applications. Among the approaches for assessing membrane target expression is quantification of the number of target-specific antibody (Ab) bound per cell (ABC). ABC determination on relevant cell subsets in complex and limited biological samples necessitates multidimensional immunophenotyping, for which the high-order multiparameter capabilities of mass cytometry provide considerable advantages. In the present study, we describe the implementation of CyTOF® for the concomitant quantification of membrane markers on diverse types of immune cells in human whole blood. Specifically, our protocol relies on establishing Bmax of Ab saturable binding on cells, then converted into ABC according to a metal's transmission efficiency and number of metal atoms per Ab. Using this method, we calculated ABC values for CD4 and CD8 within the expected range for circulating T cells and in concordance with the ABC obtained in the same samples by flow cytometry. Furthermore, we successfully conducted multiplex measurements of the ABC for CD28, CD16, CD32a, and CD64, on >15 immune cell subsets in human whole blood samples. We developed a high-dimensional data analysis workflow enabling semi-automated Bmax calculation in all examined cell subsets to facilitate ABC reporting across populations. In addition, we investigated impacts of the type of metal isotope and acquisition batch effect on the ABC evaluation with CyTOF®. In summary, our findings demonstrate mass cytometry is a valuable tool for concurrent quantitative analysis of multiple targets in specific and rare cell types, thus increasing the numbers of biomeasures obtained from a single sample.
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Affiliation(s)
- Chad R Stevens
- Biomarkers and Biomeasures, Biomedicine Design, Pfizer Inc, Andover, Massachusetts, USA
| | - Kondala Atkuri
- Biomarkers and Biomeasures, Biomedicine Design, Pfizer Inc, Andover, Massachusetts, USA
| | | | - Lindsay E King
- Biomarkers and Biomeasures, Biomedicine Design, Pfizer Inc, Andover, Massachusetts, USA
| | - Hendrik Neubert
- Biomarkers and Biomeasures, Biomedicine Design, Pfizer Inc, Andover, Massachusetts, USA
| | - Polina Goihberg
- Biomarkers and Biomeasures, Biomedicine Design, Pfizer Inc, Andover, Massachusetts, USA
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3
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Abstract
Quantification of single-cell proteomics provides key insights in the field of cellular heterogeneity. This chapter discusses the emerging techniques that are being used to measure the protein copy numbers at the single-cell level, which includes flow cytometry, mass cytometry, droplet cytometry, microengraving, and single-cell barcoding microchip. The advantages and limitations of each technique are compared, and future research opportunities are highlighted.
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Moskalensky A, Chernyshev A, Yurkin M, Nekrasov V, Polshchitsin A, Parks D, Moore W, Filatenkov A, Maltsev V, Orlova D. Dynamic quantification of antigen molecules with flow cytometry. J Immunol Methods 2015; 427:139-47. [DOI: 10.1016/j.jim.2015.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Li W, Gao Y, Pappas D. A complementary method to CD4 counting: measurement of CD4+/CD8+ T lymphocyte ratio in a tandem affinity microfluidic system. Biomed Microdevices 2015; 17:113. [DOI: 10.1007/s10544-015-0023-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Moskalensky AE, Chernyshev AV, Yurkin MA, Nekrasov VM, Polshchitsin AA, Parks DR, Moore WA, Filatenkov A, Maltsev VP, Orlova DY. Dynamic quantification of antigen molecules with flow cytometry. J Immunol Methods 2015; 418:66-74. [PMID: 25687877 DOI: 10.1016/j.jim.2015.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/29/2015] [Accepted: 02/05/2015] [Indexed: 10/24/2022]
Abstract
Traditional methods for estimating the number of expressed molecules, based on the detection of target antigens bound with fluorescently labeled antibodies, assume that the antigen-antibody reaction reaches equilibrium. A calibration procedure is used to convert the intensity of the fluorescence signal to the number of target molecules. Along with the different limitations of every calibration system, this substantially limits the applicability of the traditional approaches especially in the case of low affinity antibodies. We address this problem here with studies in which we demonstrate a new approach to the antigen molecule quantification problem. Instead of using a static calibration system, we analyzed mean fluorescence values over time by flow cytometry during antibody-antigen binding. Experimental data obtained with an LSRII cytometer were fitted by a diffusion-reaction mathematical model using the Levenberg-Marquardt nonlinear least squares curve-fitting algorithm in order to obtain the number of target antigen molecules per cell. Results were compared with the Quanti-BRITE calibration system. We conclude that, instead of using experiment-specific calibration, the value of the binding rate constant for each particular antibody-antigen reaction can be used to quantify antigen molecules with flow cytometry. The radius of CD8 antibody molecule binding site was found, that allows recalculating the binding rate constant for other conditions (different sizes of reagent molecules, fluorescent label, medium viscosity and temperature). This approach is independent of specially prepared calibration beads, antibody reagents and the specific dye and can be applied to both low and high affinity antibodies, under both saturating and non-saturating binding conditions. The method was demonstrated on a human blood sample dataset investigating CD8α antigen on T cells in stable binding conditions.
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Affiliation(s)
- A E Moskalensky
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia
| | - A V Chernyshev
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia
| | - M A Yurkin
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia
| | - V M Nekrasov
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia
| | - A A Polshchitsin
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia; JSC "Vector-Best", 630559 Koltsovo, Russia
| | - D R Parks
- Department of Genetics, Stanford University School of Medicine, 279 Campus Drive, 94305 Stanford, CA, USA
| | - W A Moore
- Department of Genetics, Stanford University School of Medicine, 279 Campus Drive, 94305 Stanford, CA, USA
| | - A Filatenkov
- Division of Immunology and Rheumatology, Stanford University School of Medicine, 269 Campus Drive, 94305 Stanford, CA, USA
| | - V P Maltsev
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova, 630090 Novosibirsk, Russia; Novosibirsk State Medical University, 52 Krasny Prospect, 630091 Novosibirsk, Russia
| | - D Y Orlova
- Institute of Chemical Kinetics and Combustion, 3 Institutskaya, 630090 Novosibirsk, Russia; Department of Genetics, Stanford University School of Medicine, 279 Campus Drive, 94305 Stanford, CA, USA.
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Pullagurla SR, Witek MA, Jackson JM, Lindell MAM, Hupert ML, Nesterova IV, Baird AE, Soper SA. Parallel affinity-based isolation of leukocyte subsets using microfluidics: application for stroke diagnosis. Anal Chem 2014; 86:4058-65. [PMID: 24650222 PMCID: PMC4004188 DOI: 10.1021/ac5007766] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
We report the design and performance
of a polymer microfluidic
device that can affinity select multiple types of biological cells
simultaneously with sufficient recovery and purity to allow for the
expression profiling of mRNA isolated from these cells. The microfluidic
device consisted of four independent selection beds with curvilinear
channels that were 25 μm wide and 80 μm deep and were
modified with antibodies targeting antigens specifically expressed
by two different cell types. Bifurcated and Z-configured device geometries
were evaluated for cell selection. As an example of the performance
of these devices, CD4+ T-cells and neutrophils were selected from
whole blood as these cells are known to express genes found in stroke-related
expression profiles that can be used for the diagnosis of this disease.
CD4+ T-cells and neutrophils were simultaneously isolated with purities
>90% using affinity-based capture in cyclic olefin copolymer (COC)
devices with a processing time of ∼3 min. In addition, sufficient
quantities of the cells could be recovered from a 50 μL whole
blood input to allow for reverse transcription-polymerase chain reaction
(RT-PCR) following cell lysis. The expression of genes from isolated
T-cells and neutrophils, such as S100A9, TCRB, and FPR1, was evaluated using RT-PCR.
The modification and isolation procedures demonstrated here can also
be used to analyze other cell types as well where multiple subsets
must be interrogated.
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Affiliation(s)
- Swathi R Pullagurla
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
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Yun H, Bang H, Min J, Chung C, Chang JK, Han DC. Simultaneous counting of two subsets of leukocytes using fluorescent silica nanoparticles in a sheathless microchip flow cytometer. LAB ON A CHIP 2010; 10:3243-54. [PMID: 20941407 DOI: 10.1039/c0lc00041h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A portable flow cytometer has been recognized as an important tool for many clinical applications such as HIV/AIDS screening in developing countries and regions with limited medical facilities and resources. Conventional flow cytometers typically require multiple detectors for simultaneous identification of multiple subsets of immune cell. To minimize the number of detectors toward portable flow cytometry or to analyze multi-parametric cellular information with minimum number of detectors in conventional flow cytometers, we propose a versatile multiplexed cell-counting method using functional silica nanoparticles (SiNPs). FITC-doped SiNPs, which are 100 times brighter than the FITC molecules itself, were used as new intensity-based fluorescent dye complexes to simultaneously measure two subsets of leukocytes using a single detector. CD45(+)CD4(+) cells tagged with these FITC-doped SiNPs were 50 times brighter than CD45(+)CD4(-) cells tagged only with FITC. To make the overall system compact, a disposable microchip flow cytometer that does not require sheath flow was developed. Combining these dye-doped SiNPs based detection schemes and the sheathless microchip flow cytometer scheme, we successfully identified and counted two subsets of leukocytes simultaneously (R(2) = 0.876). These approaches can be the building blocks for a truly portable and disposable flow cytometer for various clinical cytometry applications.
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Affiliation(s)
- Hoyoung Yun
- Institute of Advanced Machinery and Design, Seoul National University, San 56-1 Shinlim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea
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Satué K, Hernández A, Lorente C, O'Connor JE. Immunophenotypical characterization in Andalusian horse: variations with age and gender. Vet Immunol Immunopathol 2009; 133:219-27. [PMID: 19735948 DOI: 10.1016/j.vetimm.2009.08.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 08/10/2009] [Accepted: 08/14/2009] [Indexed: 10/20/2022]
Abstract
Assessment of lymphocyte subsets is an effective method for characterizing disorders such as leukemia, lymphomas, autoimmune and infectious diseases. In order to clinically interpret these parameters, normal reference values should be set, estimating age- and gender-related variations. This research aimed to: (1) characterize lymphocyte subpopulations in Andalusian horse, and (2) evaluate age and gender-related variations of lymphocyte subsets. Jugular blood samples were obtained from 159 animals, 77 males and 82 females, belonging to four age groups-1: 1-2 years (N=39; 21 males and 18 females), 2: 2-3 years (N=38; 16 males and 22 females), 3: 3-4 years (N=41; 19 males and 22 females) and 4: 4-7 years (N=41; 21 males and 20 females). T lymphocytes subsets were quantified by flow cytometry with monoclonal antibodies specific for CD2, CD4 and CD8 cell markers. B and NK cell counts were estimated by using a mathematical formula. No variations were found in T, B lymphocytes and NK cells between males and females. Animals of group 1 and 2 had a higher number of CD2, T, CD4+, CD8+, B lymphocytes and NK cells than animals of groups 3 and 4. The percentage of CD2 in group 1 was significantly lower than in group 4. The percentage of T and CD4+ lymphocytes in the group 1 were significantly higher than groups 2 and 3, respectively. Whereas the percentage of B cells calculated by flow cytometry was significantly lower in group 2 compared to group 4, the percentage of B cells calculated by a mathematical formula was higher in group 1. NK cells percentage was significantly lower in group 3 and 4 than in younger animals. In conclusion, in Andalusian horse, gender does not influence absolute numbers and percentages of T, B and NK. There is an age-related decline in absolute number of CD2, T, CD4+ and CD8+ lymphocytes, B lymphocytes and NK cells, with increasing percentage of CD2, T, CD4+ and B lymphocytes, and a decrease in NK with no differences in CD4/CD8 ratio. The decline of lymphocyte population numbers with age is a natural process in many animal species, and could be the origin for immune dysfunction observed in geriatric individuals.
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Affiliation(s)
- K Satué
- Department of Medicine and Surgery, Faculty of Veterinary Medicine, Cardenal Herrera-CEU University, Valencia, Spain.
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Wang L, Abbasi F, Gaigalas AK, Hoffman RA, Flagler D, Marti GE. Discrepancy in measuring CD4 expression on T-lymphocytes using fluorescein conjugates in comparison with unimolar CD4-phycoerythrin conjugates. CYTOMETRY PART B-CLINICAL CYTOMETRY 2007; 72:442-9. [PMID: 17474131 DOI: 10.1002/cyto.b.20354] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Numerous methods for quantitative fluorescence calibration (QFC) have been developed to quantify receptor expression on lymphocytes. However, the results from the use of these different QFC methods vary considerably in the literature. To better identify the causes of these discrepancies, we measured CD4 expression using FITC and phycoerythrin (PE) conjugates to stain CYTO-TROL Control Cells and T-lymphocytes in whole blood and isolated cell preparations. We further examined pH of the cellular microenvironment as a cause of discordant results obtained with the FITC conjugate. METHODS Calibration with Quantibrite PE-labeled microspheres and the use of unimolar CD4-PE conjugates provided direct measurement of the antibody bound per cell value (ABC) for CD4 expression on normal T-lymphocytes. Calibration for CD4-FITC monoclonal antibody (Mab) labeled CYTO-TROL Control Cells and normal T-lymphocytes was based on molecules of equivalent soluble fluorochrome (MESF) as determined by FITC-labeled microspheres traceable to NIST RM 8640. The MESF value for CD4-FITC Mab was determined that enabled the conversion of the MESF values obtained for CYTO-TROL cells to ABC. We investigated the likely pH change in the fluorescein microenvironments within FITC-labeled Mab and cells stained with FITC-labeled Mab using a pH sensitive indicator. RESULTS The mean ABC value for T-lymphocytes prepared from fresh whole blood using CD4-PE conjugate (48,321) was consistent with previous results, and it was much higher than the mean ABC using CD4-FITC Mab (22,156). The mean ABC value for CYTO-TROL cells using CD4-PE conjugate (43,090) was also higher than that using CD4-FITC conjugate (34,734), although the discrepancy was not as great. Further studies suggested the discrepancy in CYTO-TROL results may be accounted for by the low pH of the membrane microenvironment, but the greater discrepancy in T-lymphocytes could not be fully explained. CONCLUSION CD4 expression on fresh normal whole blood samples and CYTO-TROL cells can be consistently quantified in ABC units using Quantibrite PE quantification beads and unimolar CD4-PE conjugates. Quantification with CD4-FITC conjugate is not as consistent, but may be improved by the use of CD4 T-cells as biological calibrators. This approximation is valid only for surface receptors with consensus ABC values measured by different QFC methods serving as biological standards.
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Affiliation(s)
- Lili Wang
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8312, USA.
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Stewart JC, Villasmil ML, Frampton MW. Changes in fluorescence intensity of selected leukocyte surface markers following fixation. Cytometry A 2007; 71:379-85. [PMID: 17326232 DOI: 10.1002/cyto.a.20392] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Immunophenotyping of blood leukocytes often involves fixation with paraformaldehyde prior to cytometry analysis. However, the influence of cell type and marker specificity on the stability of fluorescence intensity after fixation has not been well studied. METHODS Human whole blood was stained using a panel of fluorescein isothiocyanate-labeled antibodies to surface markers. Unfixed and fixed samples were analyzed by flow cytometry at 0, 2, 4, 6, 24, 48, and 96 h after staining. Fluorescence measurements were converted to molecules of equivalent soluble fluorochrome for comparison. RESULTS Fixation caused a significant decrease in both forward and side scatter at 48 h which required gating adjustments to achieve resolution of cell populations. The autofluorescence increased progressively in fixed samples (ninefold at 96 h for monocytes). Variable decreases in marker-associated fluorescence became apparent after correction for autofluorescence. The magnitude of the decrease at 96 h varied with cell type and marker, from 5% for CD32 on monocytes to 39% for CD16 on neutrophils. CONCLUSION The change in fluorescence intensity following staining and fixation of leukocytes varies with cell type and surface marker. Fluorescence stability should be determined for each cell type and marker used, and the confounding effects of fixation on cell autofluorescence should be considered.
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Affiliation(s)
- Judith C Stewart
- Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA
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Li X, Tibbe AGJ, Droog E, Terstappen LWMM, Greve J. An immunomagnetic single-platform image cytometer for cell enumeration based on antibody specificity. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:412-9. [PMID: 17287315 PMCID: PMC1865616 DOI: 10.1128/cvi.00372-06] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Simplification of cell enumeration technologies is necessary, especially for resource-poor countries, where reliable and affordable enumeration systems are greatly needed. In this paper, an immunomagnetic single-platform image cytometer (SP ICM) for cell enumeration based on antibody specificity is reported. A chamber/magnet assembly was designed such that the immunomagnetically labeled, acridine orange-stained cells in a blood sample moved to the surface of the chamber, where a fluorescent image was captured and analyzed for cell enumeration. The system was evaluated by applying one kind of antibody to count leukocytes and one kind for each leukocyte subpopulation: CD45 for leukocytes, CD3 for T lymphocytes, and CD19 for B lymphocytes. Excellent precision and linearity were achieved. Moreover, these cell counts, each from blood specimens of 42 to 52 randomly selected patients, were compared with those obtained by SP (TruCount) and dual-platform (DP) flow cytometry (FCM) technologies. The cell counts obtained by our system were in between those obtained from the TruCount and DP FCM methods; and good correlations were achieved (R > or = 0.95). For CD4(+) counts, as we expected, the cell count by our system was significantly higher than the CD4(+) T-lymphocyte counts obtained by SP and DP FCM methods. Immunophenotyping of the immunomagnetically selected CD4(+) cells showed that, besides CD4(+) T lymphocytes, a proportion of the CD4(+) dim monocytes was also selected. Our system is a simple immunomagnetic SP ICM, which can potentially be used for enumeration of CD3(+) CD4(+) T lymphocytes in resource-poor countries if an additional CD3 immunofluorescent label is applied.
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Affiliation(s)
- Xiao Li
- Biophysical Engineering Group, University of Twente, Dienstweg 1, Building Zuidhorst, 7522 ND Enschede, The Netherlands.
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Wang L, Abbasi F, Gaigalas AK, Vogt RF, Marti GE. Comparison of fluorescein and phycoerythrin conjugates for quantifying CD20 expression on normal and leukemic B-cells. CYTOMETRY PART B-CLINICAL CYTOMETRY 2006; 70:410-5. [PMID: 16967494 DOI: 10.1002/cyto.b.20140] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Numerous methods for quantitative fluorescence calibration (QFC) have been developed to quantify receptor expression on lymphocytes as potential disease biomarkers. CD20 expression in B-cell chronic lymphocytic leukemia (B-CLL) is one of the best examples of such a biomarker, but results from the use of different QFC methods vary considerably. METHODS We measured CD20 expression on normal and B-CLL B-cells, using FITC and PE conjugates from the same monoclonal antibody (Mab). As a biological control and calibrator, we also measured CD4 expression on T-cells with FITC and PE Mab. Calibration curves were constructed using the CLSI (formerly NCCLS) consensus guidelines for QFC. Calibration with QuantiBRITE PE-labeled microspheres and the use of unimolar PE conjugates provided direct measurement of antibody bound per cell (ABC) for CD4 and CD20. Calibration for FITC conjugates was based on molecules of equivalent soluble fluorochrome (MESF), as determined by NIST RM 8640 microsphere standards. These MESF values were then converted to ABC, using the CD4 T-cell as a biologic calibrator, to normalize FITC and PE results for CD20 expression. RESULTS On normal B cells, the mean ABC value for unimolar CD20-PE conjugate was 143,500 (CV +/- 19.1%). The mean ABC value for B-CLL B-cells stained with the same conjugate was 21,700 (CV +/- 42.0%). Using the CD4 T-cell as a biologic calibrator for FITC conjugate, the mean ABC value for CD20-FITC on normal B-cells was 199,300. CD20-FITC staining on B-CLL cells was generally too weak for accurate quantification. On normal T-cells, the mean ABC value for CD4 unimolar PE conjugate was (36,800 +/- 10.4)%, and it did not differ significantly in CLL samples. CONCLUSION The expression of CD20 on normal and B-CLL lymphocytes can be quantified in ABC units using unimolar CD20-PE conjugates. In addition, CD4 expression on T-cells can be used as a biological calibrator to quantify CD20-FITC ABC, with reasonable agreement between the two conjugates with different fluorochromes. Issues regarding the accuracy of MESF microsphere calibrators and effective F/P ratios for FITC conjugates will require additional laboratory studies.
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Affiliation(s)
- Lili Wang
- Biochemical Science Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8312, USA.
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Warford A, Howat W, McCafferty J. Expression profiling by high-throughput immunohistochemistry. J Immunol Methods 2004; 290:81-92. [PMID: 15261573 DOI: 10.1016/j.jim.2004.04.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2004] [Indexed: 11/15/2022]
Abstract
Immunohistochemistry (IHC) provides valuable information on expression of proteins within tissues at a cellular and subcellular level. Recent developments in the practice of IHC now make it possible to contemplate using this technique as a high-throughput expression profiling system. Advances have been made in creation and use of tissue microarrays, in automated IHC and in image capture/analysis. Each of these technologies are reviewed and issues surrounding their use considered. The success of high-throughput IHC is also dependent on both generation and screening of appropriate antibodies. Antibody-related issues which are likely to affect the success of high-throughput IHC, such as specificity, sensitivity, fixation choice, etc., are also considered.
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Affiliation(s)
- Anthony Warford
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
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Abstract
OBJECTIVE Determine whether natural killer (NK) cells are capable of killing HIV-infected autologous primary T-cell blasts. DESIGN The ability of NK cells to kill HIV-infected primary T-cell blasts, whose cell surface major histocompatibility complex (MHC) class I molecules was decreased, was evaluated in a lytic assay. METHODS Phytohemagglutinin-treated CD4+ T cells were infected with HIV-1. Infected cells were separated from uninfected cells by removal of CD4+ T cells. The NK cells were isolated from peripheral blood mononuclear cells (PBMC) of the same donor as the CD4+ T cells by immunomagnetic bead separation. The NK cells isolated from PBMC were then used as effector cells and the HIV-infected T-cell blasts were used as target cells in a lytic assay. RESULTS It was demonstrated that HIV infection of primary CD4+ T cells results in a 61-68% reduction in surface expression of MHC class I molecules. Despite the decreased MHC class I expression the NK cells were incapable of lysing autologous HIV-infected T-cell blasts, yet were effective in the lysis of the NK cell sensitive cell line, K562. The inability of NK cells to lyse HIV-infected T-cell blasts is not dependent on the strain of HIV used to infected the CD4+ T cell CONCLUSION These studies indicate that despite drastic decreases in MHC class I molecule expression, HIV-infected T-cell blasts can evade destruction by autologous NK cells.
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Affiliation(s)
- Matthew I Bonaparte
- Department of Microbiology and Immunology, University of New York, Upstate Medical University, Syracuse, New York 13210, USA
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Abstract
Infection of humans with influenza A virus (IAV) results in a severe transient leukopenia. The goal of these studies was to analyze possible mechanisms behind this IAV-induced leukopenia with emphasis on the potential induction of apoptosis of lymphocytes by the virus. Analysis of lymphocyte subpopulations after exposure to IAV showed that a portion of CD3(+), CD4(+), CD8(+), and CD19(+) lymphocytes became apoptotic (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling positive). The percentage of cells that are infected was shown to be less than the percentage of apoptotic cells, suggesting that direct effects of cell infection by the virus cannot account fully for the high level of cell death. Removal of monocytes-macrophages after IAV exposure reduced the percent of lymphocytes that were apoptotic. Treatment of virus-exposed cultures with anti-tumor necrosis factor alpha did not reduce the percentage of lymphocytes that were apoptotic. In virus-exposed cultures treated with anti-FasL antibody, recombinant soluble human Fas, Ac-DEVD-CHO (caspase-3 inhibitor), or Z-VAD-FMK (general caspase inhibitor), apoptosis and production of the active form of caspase-3 was reduced. The apoptotic cells were Fas-high-density cells while the nonapoptotic cells expressed a low density of Fas. The present studies showed that Fas-FasL signaling plays a major role in the induction of apoptosis in lymphocytes after exposure to IAV. Since the host response to influenza virus commonly results in recovery from the infection, with residual disease uncommon, lymphocyte apoptosis likely represents a part of an overall beneficial immune response but could be a possible mechanism of disease pathogenesis.
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Affiliation(s)
- J E Nichols
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, 301 University Ave., Galveston, TX 77555-0435, USA.
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18
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Barnett D, Storie I, Granger V, Whitby L, Reilly JT, Brough S, Garner S, Lawry J, Richards S, Bell AE, Shenton BK. Standardization of lymphocyte antibody binding capacity - a multi-centre study. CLINICAL AND LABORATORY HAEMATOLOGY 2000; 22:89-96. [PMID: 10792398 DOI: 10.1046/j.1365-2257.2000.00286.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
As quantitative flow cytometry is being increasingly used to characterize non-malignant and malignant disorders, interlaboratory standardization becomes an important issue. However, the lack of standardized methods and process controls with predefined antibody binding capacity values, limits direct interlaboratory comparison. The present study has addressed these issues using a stable whole blood product and a standardized antigen quantification protocol. It was demonstrated that: (i) a standard technical protocol can result in a high degree of interlaboratory concordance; (ii) interlaboratory variation of less than 12% can be achieved for CD4 antibody binding capacity values; and (iii) stable whole blood can be used as a process control with predefined antibody binding capacity values. Furthermore, using such an approach, a normal range was established for CD3, CD4 CD8 and CD19. These antigens appear to be expressed in a hierarchical manner, a factor that could be used as a procedural quality control measure.
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Affiliation(s)
- D Barnett
- UK NEQAS for Leucocyte Immunophenotyping, Royal Hallamshire Hospital (co-ordinating centre), Sheffield, UK.
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19
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Jabs WJ, Paulsen M, Wagner HJ, Kirchner H, Klüter H. Analysis of Epstein-Barr virus (EBV) receptor CD21 on peripheral B lymphocytes of long-term EBV- adults. Clin Exp Immunol 1999; 116:468-73. [PMID: 10361236 PMCID: PMC1905320 DOI: 10.1046/j.1365-2249.1999.00912.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Primary infections with EBV are rarely observed after the age of 20. Some individuals even remain seronegative all their lives. Previously, a lack of EBV receptors on B cells of persistently EBV- adults was described as a reason for long-term EBV-seronegativity. The present study examined the CD21 receptor status of 20 repeatedly EBV- healthy adults and 32 EBV+ volunteers by means of flow cytometry. CD21 molecules on the surface of CD19+ B cells were quantified using anti-IgG-coated microbeads. The percentage of CD19+/CD21+ B lymphocytes was slightly lower in the peripheral blood of EBV- donors, but the CD21 antibody binding capacity on CD19+ B cells showed no significant differences between EBV- and EBV+ adults. In vitro studies showed an equally good EBV transformability of peripheral B lymphocytes of EBV- and EBV+ donors. Since HLA-DR was recently described as a co-receptor for EBV infection of B cells, we also determined HLA-DRB1 alleles in the EBV- group. We found a significant negative association of EBV-seronegativity with HLA-DR13 in comparison with 111 healthy blood donors. In summary, a biologically significant lack of the EBV receptor CD21 on peripheral B lymphocytes of persistently EBV- adults was excluded as a reason for long-term EBV-seronegativity.
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Affiliation(s)
- W J Jabs
- Institute of Immunology and Transfusion Medicine, Department of Paediatrics, University of Lübeck School of Medicine, Lübeck, Germany.
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20
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Flaminio MJB, Rush BR, Shuman W. Peripheral Blood Lymphocyte Subpopulations and Immunoglobulin Concentrations in Healthy Foals and Foals with Rhodococcus equi Pneumonia. J Vet Intern Med 1999. [DOI: 10.1111/j.1939-1676.1999.tb02180.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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21
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Serke S, Johnsen H, Huhn D, Kvalheim G. European survey of the flow cytometric determination of CD34-expressing cells. Cytotherapy 1999; 1:343-7. [DOI: 10.1080/0032472031000141275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Dumont LJ, VandenBroeke T, Ault KA. Platelet surface P-selectin measurements in platelet preparations: an international collaborative study. Biomedical Excellence for Safer Transfusion (BEST) Working Party of the International Society of Blood Transfusion (ISBT). Transfus Med Rev 1999; 13:31-42. [PMID: 9924762 DOI: 10.1016/s0887-7963(99)80086-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Taji H, Kagami Y, Okada Y, Andou M, Nishi Y, Saito H, Seto M, Morishima Y. Growth inhibition of CD20-positive B lymphoma cell lines by IDEC-C2B8 anti-CD20 monoclonal antibody. Jpn J Cancer Res 1998; 89:748-56. [PMID: 9738982 PMCID: PMC5921892 DOI: 10.1111/j.1349-7006.1998.tb03280.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Treatment with IDEC-C2B8 (C2B8), the chimeric anti-CD20 antibody, was shown in a phase I-II study to be very effective for the treatment of low-grade B-cell lymphoma, in contrast to the results of most previous immunotherapies with monoclonal antibodies. In a study designed to elucidate the reason for this efficacy, two cell lines derived from lymphomas with BCL2 gene rearrangement (SU-DHL-4 and SU-DHL-6) showed remarkable growth inhibition and cell-death, and two other cell lines derived from a diffuse lymphoma (RC-K8) and a mantle cell lymphoma (SP-49) showed moderate growth inhibition, but neither a CD20 weakly positive cell line (NALL-1) nor a negative cell line (MOLT-4) showed any growth inhibition. An examination of the intensity of cell-surface CD20 expression showed no correlation between intensity and degree of growth inhibition among the four cell lines showing growth inhibition. Morphological examination revealed condensed and fragmented nuclei and budding of the plasma membrane, both characteristic of apoptosis, with some cells in these cell lines showing growth inhibition by C2B8. Such apoptosis was also confirmed by flow cytometric analysis, suggesting that, at least in part, apoptosis plays a role in this growth inhibition. This growth-inhibitory mechanism may thus account for the effectiveness of C2B8 antibody therapy.
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Affiliation(s)
- H Taji
- Department of Hematology and Chemotherapy, Aichi Cancer Center Hospital, Nagoya
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24
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Serke S, Huhn D. Circulating CD34-expressing cells: German Proficiency Testing Survey. JOURNAL OF HEMATOTHERAPY 1998; 7:37-43. [PMID: 9507379 DOI: 10.1089/scd.1.1998.7.37] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Determination of absolute numbers of CD34-expressing cells is critical in the setting of peripheral blood stem and progenitor cell transplantation/reinfusion. The diagnostic value of the parameter, CD34-expressing cells/microliter, has been validated. A survey of CD34-expressing cells has been integrated into a series of flow cytometry proficiency testing surveys (reticulocytes, lymphocytes, leukemia, and lymphoma) that we have established in Germany. Commercially available, modified, stabilized myeloblastic leukemia cells (KG1a cell line) spiked at different numbers into two normal blood samples were sent out, and report forms were returned from 50 of 58 participants. With a predicted percentage of CD34-expressing cells of 0.5% (sample A) and of 0.25% (sample B), the respective mean values analyzing data from 44 participants returning the completed forms were 0.49% (sample A) and 0.29% (sample B). The coefficients of variation were 57% and 83%, respectively. Engineered samples based on normal blood and on commercially available stabilized modified KG1a cells seem to be reliable material for external quality assessment surveys of CD34-expressing cells.
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Affiliation(s)
- S Serke
- Department of Internal Medicine, Virchow-Klinikum, Humboldt-University, Berlin, Germany
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