CD8A and infection: It is important to note that overall increase in 2° CD8 T cell accumulation in the ‘late’ group is facilitated by both antigenic stimulation and increased sensitivity to IL-2 signals following complex treatment, as 1° M CD8 T cells activated with the stimulatory IL-2/S4B6 complexes in the absence of infection undergo a moderate level of homeostatic driven proliferation (S5 Fig).