Human Immune Response Cellular and biochemical processes that protect humans from the effects of foreign substances– usually microorganisms and their proteins

How do you know your immune system is working? Looks like Sounds like Feels like

What happens during the immune response?  Organism Feels sick/’crummy’: fever, tired, achy  Organ Systems Cardiovascular, Lymphatic, Endocrine  Cells Increased white blood cell (leukocyte) count  Biochemicals Production of immune response proteins – antibodies and inflammatory chemicals

Immune Response – Overview Barriers Mechanical Chemical Non- Specific Response Fever Inflammation Phagocytosis Specific Response Cell Mediated – T cells Humoral Mediated – B cells Memory/Immunity Recognize and Respond Prevent Remember

Results When the human immune response is activated the results include:  Disease symptoms  Allergies and allergic reactions  Acquired immunity from vaccinations  Autoimmune diseases (ie. lupus, ALS, rheumatoid arthritis, multiple sclerosis)  Organ and tissue rejection

Prevention  Barriers act to prevent pathogens from entering the body  Mechanical Barriers  Skin  Mucous membranes, hair, sweat  Chemical Barriers  Enzymes (various organs)  Phagocytes (neutrophils and monocytes)  Secretions (mucus, sweat …)

Recognize  Immune system recognizes proteins as ‘self’ or ‘non-self’  Non-self proteins are called antigens and are found on the surface membranes of pathogens  Antigens associated with bacteria, fungi, viruses:  attract neutrophils to begin phagocytosis  provoke an immune response when identified by lymphocytes called helper T-cells

Response

Response - Non-Specific  Non–specific response = same response to any antigen  Response is fast, but inefficient  Traits shared by large number of pathogens are recognized using small number of receptors

Response - Non-Specific  Inflammation  Histamine from basophils cause capillaries to dilate and neutrophils leak out to site of infection  Creates a barrier of proteins around infected site to help prevent spread to other tissues  Inflammatory Response Video Inflammatory Response Video

Response - Non-Specific  Fever  Chemicals produced by basophils and eosinophils increase metabolic rate and body temperature  Increased temperature:  increases production of neutrophils and metabolic activity of phagocytes  slows bacterial growth and reproduction

Response - Non-Specific  Phagocytosis  Neutrophils become phagocytes and engulf/digest cells marked with non-self proteins  Monocytes become macrophages and engulf/digest cells marked with non-self proteins macrophage phagocyte

Response – Specific  Specific response is slower, but more efficient, than the non-specific response  Specific response = a response that is different for every antigen (ie. specific to that antigen). Uses a vast array of receptors  Specific response is carried out by two types of lymphocytes  T-cells develop in thymus gland and do cell-mediated response  B- cells develop in bone marrow and do antibody-mediated (humoral) response

Response – Specific  Cell-mediated response (T-cells)  Cytotoxic (killer) T cells – transfer proteins inside cells with specific antigen, membrane leak, cell dies.  Helper T cells – stimulate division of B cells.  Both killer and helper T cells give rise to memory T cells.  Killer T Cell Video Killer T Cell Video

Response – Specific  Antibody-mediated (humoral) response (B-cells)  B-cells become plasma cell that produce antibodies and release them in blood stream.  Antibodies are specific for a particular antigen. They bind to antigen and either:  Cause agglutination (then phagocythized)  Inactivate pathogens directly  B-cells also produce memory B-cells

Response – Specific  Antibodies are special proteins that can bind to an antigen and mark it for destruction by other specific and nonspecific mechanisms

Response – Specific

Remember  Memory T and B cells remain dormant after 1 st exposure.  2 nd exposure: specific cytotoxic T cells, helper T cells and plasma cells produced faster and in larger numbers. Strong, fast response.  Results in “natural immunity”.  “Artificial immunity” by vaccination.

video Vaccinations – artificial immunity  Weakened bacteria and viruses  antigens stimulate primary immune response without symptoms.

Immune Response - Summary  Immune Response Video Immune Response Video  Immune Response Video Immune Response Video

Autoimmune Disorders  Immune system cannot distinguish between self and non-self antigens.

Autoimmune Disorders

Allergies  Immune response to allergens = non-harmful antigens.  Histamine release and inflammatory response.