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Cell-mediated immunity is an immune response that does not involve antibodies or complement but rather involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells. CD4 cells or helper T cells provide protection against different pathogens.

Cellular immunity protects the body by:

1. activating antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens;
2. activating macrophages and natural killer cells, enabling them to destroy intracellular pathogens; and
3. stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses.

Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria. It also plays a major role in transplant rejection.

v • d • e Blood (WBC and RBC) Cellular/ HSCs Myeloid/ Myeloblast CFU-GEMM CFU-GM CFU-G: Granulocytes Band cell · Neutrophil CFU-M: Monocytes Macrophages Histiocytes · Kupffer cells · Alveolar macrophage · Microglia · Osteoclasts · Epithelioid cells · giant cells (Langhans giant cells, Foreign-body giant cell, Touton giant cells) CFU-DL Dendritic cells (Langerhans cells, Follicular dendritic cells) Common Myelomonocyte CFU-Baso Granulocytes (Basophil) CFU-Eos Granulocytes (Eosinophil) MEP CFU-Meg Megakaryoblast · Megakaryocyte · Platelets CFU-E Reticulocyte · Normoblast CFU-Mast Mast cell precursors Noncellular Plasma myeloid navs: cells/physio, disease of RBCs+megakaryocytes/monocytes+granulocytes/neoplasia, symptoms+signs/eponymous

v • d • e Immune system / Immunology Systems Adaptive vs. Innate · Humoral vs. Cellular · Complement (Anaphylatoxins) · Intrinsic Lymphoid Antigens Antigen (Superantigen, Allergen) · Hapten Epitope (Linear, Conformational) Antibodies Antibody (Monoclonal antibodies, Polyclonal antibodies, Autoantibody) · Polyclonal B cell response · Allotype · Isotype · Idiotype Immune complex Immunity vs. tolerance action: Immunity · Autoimmunity · Alloimmunity · Allergy · Inflammation · Cross-reactivity inaction: Tolerance (Central, Peripheral, Clonal anergy, Clonal deletion, Tolerance in pregnancy) · Immunodeficiency Immunogenetics Somatic hypermutation · V(D)J recombination · Junctional diversity  · Immunoglobulin class switching · MHC/HLA Immune cells/ White blood cells Lymphoid: T cell · B cell · NK cell Myeloid: Mast cell · Basophil · Eosinophil · Phagocytes (Neutrophil, Macrophage/Reticuloendothelial system) Professional APCs: Dendritic cell · Macrophage · B cell Substances Cytokines · Opsonin · Cytolysin Lymphopoiesis Lymphoblast · Prolymphocyte Other Diagnostic immunology · Plant disease resistance lymphocyte navs: cells/physio, immunodeficiency/immunoproliferative immunoglobulin/neoplasia, proc

v • d • e Immune disorders: hypersensitivity and autoimmune diseases Type I/allergy/atopy (IgE) Foreign Atopic dermatitis · Allergic urticaria · Hay fever · Allergic asthma · Anaphylaxis · Food allergy (Milk, Egg, Peanut, Tree nut, Seafood, Soy, Wheat), Penicillin allergy Autoimmune none Type II/ADCC (IgM, IgG) Foreign Pernicious anemia · Hemolytic disease of the newborn Autoimmune Cytotoxic Autoimmune hemolytic anemia · Idiopathic thrombocytopenic purpura  · Bullous pemphigoid  · Pemphigus vulgaris · Rheumatic fever · Goodpasture's syndrome "Type 5"/receptor Graves' disease · Myasthenia gravis Type III (Immune complex) Foreign Henoch-Schönlein purpura · Hypersensitivity vasculitis · Reactive arthritis · Rheumatoid arthritis · Farmer's lung · Post-streptococcal glomerulonephritis · Serum sickness · Arthus reaction Autoimmune Systemic lupus erythematosus · Subacute bacterial endocarditis Type IV/cell-mediated (T-cells) Foreign Contact dermatitis · Mantoux test Autoimmune Diabetes mellitus type 1 · Hashimoto's thyroiditis · Guillain–Barré syndrome  · Multiple sclerosis  · Coeliac disease · Giant cell arteritis GVHD Transfusion-associated graft versus host disease Unknown/ multiple Foreign Hypersensitivity pneumonitis (Allergic bronchopulmonary aspergillosis) · Transplant rejection · Latex allergy (I+IV) Autoimmune Sjögren's syndrome · Autoimmune hepatitis · Autoimmune polyendocrine syndrome (APS1, APS2) · Autoimmune adrenalitis lymphocyte navs: cells/physio, immunodeficiency/immunoproliferative immunoglobulin/neoplasia, proc

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