• Includes the thymus, spleen, lymphatic system, bone marrow, tonsils, and Peyer's patches, and the migratory cells these organs generate: lymphocytes, granulocytes, and cells of the monocyte- macrophage type.
  CRISP Thesaurus
  National Institutes of Health, 2006
• The body's defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• The complex group of organs and cells that defends the body against infection or disease.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• The complex group of organs like thymus, spleen, tonsils, lymphatic system, hematopoetic system and cells like lymphocytes, granulocytes, monocytes and macrophages that defends the body against infection or disease. It consists of a complex interrelated cellular, molecular and genetic component.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• The immune system distinguishes self from nonself and eliminates potentially harmful nonself molecules and cells from the body. The immune system also has the capacity to recognize and destroy abnormal cells that derive from host tissues. Any molecule capable of being recognized by the immune system is considered an antigen (Ag).
  Merck Manuals
  Merck & Co., Inc., 2020
• The immune system is an inherent self-defense system consisting of cells that helps the body distinguish between self and non-self molecules. Different pathways regulate different immune cells to help the body differentiate the bodies own healthy cells from disease-causing agents including bacteria, viruses, fungi, parasites, cancerous...
  Medscape
  WebMD, 2019
• Immune system, the complex group of defense responses found in humans and other advanced vertebrates that helps repel disease-causing organisms (pathogens). Immunity from disease is actually conferred by two cooperative defense systems, called nonspecific, innate immunity and specific, acquired...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2020