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Table 2 Description of parameter values involved in the IL-7 dynamics

From: Improving cancer detection through combinations of cancer and immune biomarkers: a modelling approach

Parameter Description (units) Baseline values
\(a_{i}\) CD8\(^{+}\) T cells doubling time (day\(^{-1}\)) 2.0794
\(d_{i}\) CD8\(^{+}\) T cells half-life (day\(^{-1}\)) 0.4
\(d_{t}\) Killing rate of tumour cells by immune effector cells (day\(^{-1}\)) \(10^{-6}\)
\(k_{ei}\) IL-7 half life (day\(^{-1}\)) 2.14
M Carrying capacity of immune cells \(10^{9}\)
\(f_{i}R_{i}\) Influx of IL-7 secreted by immune cells, into the vasculature ((pg/ml)/cell/day) \(10.925\times 10^{-6}\)
\(f_{hi}R_{hi}N_{h}\) Healthy cells shedding influx of IL-7 (pg/day) \(1.9548\times 10^{4}\) (low shedding); or \(7.1724\times 10^{4}\) (high shedding)
\(c_{IL7}\) Cut-off limit of IL-7 assay (for healthy vs. disease states), when the biomarker is produced by both immune and healthy cells (pg/ml) 3.8 (low threshold) or 18 (high threshold)
\(d_{IL7}\) Detection limit of IL-7 assay (i.e., min concentration of IL-7 detectable in plasma), when the biomarker is produced by the immune cells alone (pg/ml) 1.0
\(V_{pl}\) Mean plasma volume in a 70-year female patient (ml) 3150
\(D_{T}^{t}\) Tumour detection time based on the CA-125 biomarker (days) To be determined
\(D_{T}^{i}\) Tumour detection time based on the IL-7 biomarker (days) To be determined