Human NK Cells Differ More in Their KIR2DL1-Dependent Thresholds for HLA-Cw6-Mediated Inhibition than in Their Maximal Killing Capacity
A) The Basic model. The variables represented by this model are: N – the number of free NK cells; T – the number of free target cells; and C – the number of NK-target cell conjugates. The Parameters that govern the behaviour of these populations are: β - the conjugation rate (cells*min)−1; τ - the conjugate lifetime (min), such that conjugates will break up at rate 1/τ (min)−1; and κ - the death rate of post-encounter target cells, such that (1-κ) is the fraction of living targets returning to the free target population. B) Model with a delay in cell death. Here, Td is the number of dying target cells; they die at rate µ ((min)−1), such that 1/µ is the dying target cell lifetime (min). C) Model with a delay in cell activation. The model version shown here does not include target cell death delay. The variables here are: Nr – the number of free resting NK cells; Na – the number of free activated NK cells; T – the number of free target cells; Cr –the number of cell conjugates of target and resting NK cells; and Ca – the number of cell conjugates of target and activated NK cells. Parameters are the same as in the basic model, except for different conjugation and dissociation rates for resting and activated NK cells: βr and τr for resting and βa and τa for activated NK cells, respectively.