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Table 4 Model parameter values for the LEUKOCYTE MEMBRANE and LIGANDS along with corresponding in vitro values

From: Dynamics of in silico leukocyte rolling, activation, and adhesion

Parameter Name Description Model Parameter Value Experimental Value Reference
LeukTotalWidth LEUKOCYTE MEMBRANE width (in the y [east-west] dimension) 20 MEMBRANE UNITS Avg. Human Leukocyte Diameters (μm): Lymphocyte: 6.2; Neutrophil: 7; Monocyte: 7.5 [48]
LeukTotalLength LEUKOCYTE MEMBRANE length (in the x [north-south] dimension) 30 MEMBRANE UNITS   
LeukExposedWidth CONTACT ZONE width (in the y dimension) 8 MEMBRANE UNITS NA NA
LeukExposedLength CONTACT ZONE length (in the x dimension) 10 MEMBRANE UNITS NA NA
PSGL1DensityMean ± PSGL1DensitySTDev Mean number of PSGL-1 molecules (± SD) represented by each PSGL1 agent Experiment 1: Neutrophils 150 ± 5a molecules ~18,000/Human Neutrophil [54]
   Experiment 3: Monocytes 150 ± 5b molecules N/A N/A
VLA4DensityMean ± VLA4DensitySTDev Mean number of VLA-4 molecules (± SD) represented by each VLA4 agent Experiment 2: T-lymphocytes 45 ± 5 molecules 3,000/Human T-Lymphocyte [55]
   Experiment 3: Monocytes 60 ± 5 molecules 6,000/Human Monocyte  
CXCR2DensityMean ± CXCR2DensitySTDev Number of CXCR-2 molecules (± standard deviation) represented by each CXCR2 agent 1 ± 0 molecules NA NA
VLA4MaxPercHighAff Maximum percent of VLA-4 integrins on the leukocyte membrane that can be induced into a high affinity statec 12.5% 10% [49]
Pon (PSGL1-PSELECTIN1) Probability of forming a PSGL1-PSELECTIN1 BOND 0.001 NAd [56]
Pon (LOW AFFINITY VLA4-VCAM1) Probability of forming a LOW AFFINITY VLA4-VCAM1 BOND 0.001 NAd [55]
Pon (HIGH AFFINITY VLA4-VCAM1) Probability of forming a HIGH AFFINITY VLA4-VCAM1 BOND 0.005 NAd [55]
Pon (CXCR2-GROA) Probability of forming a CXCR2-GROA BOND 1.0c NA NA
Poff (CXCR2-GROA) Probability of breaking a CXCR2-GROA BOND 1.0c NA NA
  1. a PSGL1DensityMean ± PSGL1DensitySTDev parameter values used for simulating Experiment 1, neutrophil rolling, were originally 25 ± 5. They were changed to the values currently listed to more closely reflect the experimental values of PSGL-1 density reported in the literature. No significant differences were observed when using these new parameter values.
  2. b Values for PSGL-1 sites/human monocyte were not found in the literature and were assumed to be similar to values reported for human neutrophils.
  3. c See Methods.
  4. d Pon and Kon are intended to map to aspects of the same in vitro phenomena. However, there is no direct mapping between these parameters because the parent models belong to fundamentally different classes [57].