FIGURE 2.

Antigen specific characteristics affect Memory Population Size and antigen independent mechanisms affect EM/CM ratio for CD4+ T cells. (A) Simulation set-up: Ag-specific mechanisms have varying affects on Ag-specific T cell populations (numbered circles) within a single LN. Ag-independent mechanisms, here conceptualized as three different LN environments, cause variations in cells from the same Ag-specific population. (B) Binding probability affects the number of CD4+ T cells generated in LN. y-axis: total numbers of T cells in blood and peripheral tissue. x-axis: days post-vaccination. CD4+ T cell populations were assigned increasing binding thresholds (a_i) from low (Ag1-specific T cells) to high (Ag5-specific T cells) such that the binding probability, P_i(bind), of Ag1-specific T cells was highest, followed by Ag2-specific T cells, and so on with Ag5-specific T cells having a very low chance of binding their matching p_iMHC presented on the surface of a DC. All parameters were at baseline values, except binding thresholds, which were set at 30, 90, 150, 200, 300 for Ag1-Ag5, respectively. (C) Binding time affects amount of CM, but not EM, generated. Numbers of CD4+ T cells in blood and tissue are plotted post-vaccination for 3 simulations, with DC-T cell binding time (max binding time Naïve) increasing from LN 1 (4 h) to LN 2 (8 h) to LN 3 (12 h). (D) Memory T cell populations at 30 days post-vaccination corresponding to time courses in panel B are plotted in Memory Design Space. Colors show binding probability from low (blue) to high (red) and correspond to graphs in Panel B. Error bars represent SEM (n = 10). (E) T cell populations measured 30 days post-vaccination in blood and peripheral tissues corresponding to time courses in panel C are plotted in Memory Design Space. Purple: LN 1, Red: LN 2, Orange: LN 3. Error bars represent SEM (n = 10). See Supplementary Figure S1 for statistical analysis of change in skew.