Table 4

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

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

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.

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.

c See Methods.

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].

Tang et al. BMC Systems Biology 2007 1:14   doi:10.1186/1752-0509-1-14