PMEL and neoplasm: However, no significant change was observed in the spleen (Fig. 6a), indicating that both the production of IFN-γ and TNF-α and consequent Treg depletion is restricted to tumor tissue, presumably due to local production of IFN-γ and TNF-α by CD8+ Teff encountering cognate gp100 tumor Ag in tumor but not in spleen.