This is the MATLAB source code for a stochastic agent-based model of CD8+ T cell responses following vaccination. The model simulates T cell activation, proliferation, contraction, and differentiation into effector and memory populations. Cell division is regulated by intracellular c-Myc dynamics, and the model includes asymmetric inheritance of c-Myc between daughter cells. A lineage tracking module is also added to follow the descendants and division histories of individual simulated T cell families.