Immune system - what is and definition

Immune system - The structures, substances, and processes that protect the body from INFECTION. These include organs, tissues, cells, and molecules. The immune system functions in close collaboration with the NERVOUS SYSTEM and the endocrine system.

The main organs and tissues of the immune system include

• BONE MARROW
• THYMUS
• SPLEEN
• lymph nodes
• BLOOD
• LYMPH
• adenoids and tonsils
• APPENDIX
• MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT)
• SKIN
• tears
• saliva

The primary cells of the immune system include

• B-cell lymphocytes (PLASMA cells, memory Bcells)
• T-cell lymphocytes (helper T-cells, cytotoxic Tcells, memory T-cells, suppressor T-cells)
• granulocytes (neutrophils, eosinophils, and basophils)
• macrophages and dendritic cells
• mast cells
• monocytes
• M cells
• natural killer (NK) cells Key molecules of the immune system include
• HUMAN LEUKOCYTE ANTIGENS (HLAs)
• complement factors
• CLUSTERS OF DIFFERENTIATION
• IMMUNOGLOBIN
• antigens
• antibodies
• PROSTAGLANDINS
• HISTAMINE
• LEUKOTRIENES
• CYTOKINES (CHEMOKINES, INTERLEUKINS, MONOKINES, INTERFERONS, LYMPHOKINES, COLONY-STIMULATING FACTORS [CSFS], and TUMOR NECROSIS FACTORS [TNFS])

For further discussion of the structures and functions of the immune system, please see the overview section “The Immune System and Allergies.”

See also ANTIBODY; ANTIGEN; ANTIBODY-MEDIATED IMMUNITY; B-CELL LYMPHOCYTE; CELL-MEDIATED IMMUNITY; COMPLEMENT CASCADE; GRANULOCYTE; IMMUNE RESPONSE; LYMPH NODE; LYMPHOCYTE; MACROPHAGE; MAJOR HISTOCOMPATIBILITY COMPLEX (MHC); MONOCYTE; NATURAL KILLER (NK) CELL; PSYCHONEUROIMMUNOLOGY; T-CELL LYMPHOCYTE.

Open discussion on the topic Immune system - what is and definition