Immune system is composed of innate and adaptive responses and plays critical roles in cancer development and destruction. A century ago, Paul Ehrlich postulated that cancer would be quite common in long-lived organisms if not for the protective effects of immunity. About 50 years later, Burnet and Thomas proposed the concept of cancer immunosurveillance based on the experimental evidence of immune recognition of tumor antigens expressed on tumor cells (Dunn et al. 2004 ) . In 1971, the US Congress created a National Cancer Act – a War on Cancer. Among many tough questions asked were whether the immune system can be manipulated so that it recognizes tumor.
