CD8A and neoplasm: Treatment with the combination therapy also led to significantly increased numbers of activated, proliferating CD8+ T cells compared to either CD8+ T cells isolated from animals treated with HPPH or tumor-controlling PDT (P ≤ 0.01); the increase in activated, proliferating CD8+ T cells following the combination therapy was not significantly different from the increase induced by the immune-enhancing PDT regimen (P ≤ 0.2).