TY - CHAP M1 - Book, Section TI - The Immune System and Immunotherapy A1 - Saibil, Samuel D. A1 - Wang, Ben X. A1 - Butler, Marcus O. A2 - Harrington, Lea A. A2 - Tannock, Ian F. A2 - Hill, Richard P. A2 - Cescon, David W. PY - 2021 T2 - The Basic Science of Oncology, 6e AB - One feature that is common to all organisms is the ability to defend themselves against challenges in the environment in which they live. Mammals have a complex phalanx of defenses against bacteria, viruses, and parasites, which comprise the immune system. The immune system can be characterized broadly as having 2 major arms: innate immunity and adaptive immunity. The innate immune system is the “first line of defense” against pathogens and includes macrophages and dendritic cells that function in part to present antigens to the cells in the adaptive immune system. The adaptive arm of the immune system is mediated by lymphocytes and responds with higher specificity to pathogens. Key cells of the adaptive immune system are helper T cells (TH) that express a marker known as CD4, cytotoxic T lymphocytes (CTL) that are distinguished by the CD8 marker, and B cells that produce antibodies. The molecular components of pathogens that are recognized by T and B cells are referred to broadly as antigens. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - hemonc.mhmedical.com/content.aspx?aid=1179325974 ER -