 To attack tumor cells and viruses, CD-4 cells coordinate the overall immune response and help activate CD8 T-lymphocytes.Often called “effector” or “cytotoxic” T-cells, CD-8+ T-lymphocytes they respond to intracellular pathogens and cancer cells.Under viral attack CD-4+ T-cells fail to mature, fail to produce IL-2 and gamma interferon, and consequently fail to coordinate CD-8 responses to viruses.