IL4 and neoplasm: Young TIL cultures comprised of more than 90% of CD3+ T cells, a variable percentage of CD3+CD8+ and CD3+ CD4+ T cells, and less than 10% of CD3-CD16+ NK cells, a similar phenotype of EBV-CTL cultures from PBMCs.TIL cultures secreted high levels of the Th1 cytokines, IFNγ and TNF-α, and low levels of the Th2 cytokines, IL-4 and IL-10.Young TILs could recognize autologous EBV-transformed B lymphoblast cell lines, but not autologous EBV-negative blast cells or allogeneic EBV-negative tumor cells.