IL4 and benign prostatic hyperplasia: In addition, most tissue samples collected from patients with BPH are infiltrated by a vastly increased population of T lymphocytes, which release a variety of inflammatory cytokines, such as interleukin (IL)-1β, IL-2, IL-4, IL-6, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α, which play important roles in the maturation of the stroma and development of stromal nodules in BPH [9].