Innate Immunity Innate immunity The first and second lines of defense Non specific to an invader o First line of defense skin is intact Includes mucous membranes and their secretions and normal microbiota o Second line of defense Skin is breached We need phagocytosis Phagocytes will come and eat those bitches coupled with fever and inflammation and antimicrobial substances Neutrophil and macrophage the major phagocytic cells in the human body Interferons proteins that protect uninfected cells from viruses Only get created once a viral infection is present somewhere else in the body Nonspecific Monocytes are immature macrophages which mature outside of the blood vessel o Inflammation Oh Jesus I lightly stabbed myself Damaged cells release some crazy ass chemicals causing dilation of the blood cells So blood moves into the area to kill those bitches which causes the swelling Neutrophils in the bloodstream squeeze through the blood vessel wall into damaged areas to start eating those motherfuckers Phagocytosis the desired end result of any foreign microbe or whatever invasion What is happening o Seven stages chemotaxis and adherence of phagocyte to microbe Ingestion of microbe by phagocyte Formation of phagosome phagocytic vessel Fusion of phagosome with lysosome to form phagolysosome Digestion of ingested microbes by enzymes in the phagolysosome Formation of residual body containing indigestible material Discharge of waste materials o Chemotaxis allows phagocytes to migrate to infection sites and destroy invading bacteria o Phagocytosis is an important second line of immune defense Phagocytes can also stimulate T and B cells more on those later o The mechanism of killing is H2O2 in the cytoplasm combined with Myeloperoxidase in the lysosome plus chlorine ions to create hypochlorite o Chronic Granulomatous Disease is a genetic disorder that induces an inability of phagocytes to make H2O2 These individuals suffer from repeated bacterial infections Mycobacterium tuberculosis lives in the phagocytic cell I don t know what else to do with this information Fever a second line of defense What is happening Macrophage ingest a gram negative bacterium Bacterium is degraded in a vacuole releasing endotoxins that induce the macrophage to produce cytokines IL 1 and TNF a Cytokines are released into bloodstream go to hypothalamus in brain which produces prostaglandins resetting the body s temperature pyrogenic response o A fever is essentially the speeding up of cellular activity You ll find that small cuts and bruises heal faster when you have a fever Adaptive Immunity Specific immunity resistance to a specific invader Body reacts against non self but not self The third line of immunodefense is specific Antigen foreign material that induces an immune response They must be foreign to host and reasonably large 10 000 MW Usually proteins or polysaccharides Note cyanide is not an antigen because it is too small Antibodies protein molecules synthesized in response to the presence of an antigen Once formed it will combine with an antigen They are also called immunoglobulins Ig 481 Humoral Immunity a quick overview Foreign bodies have little components of the cell walls that are antigens in themselves These antigens have chemical groups on their surfaces called epitopes or antigenic determinants Antibodies are made to bind with a specific kind of epitope Most antibodies are Y shaped with two epitope binding sites There are 5 common types or immunoglobulins compounded antibody structures o IgG a monomer most common A single Y antibody the kind of antibody in a flu shot serum o IgM The first antibody on the scene Less common 5 Y s It fixes complement o IgA Secretory immunoglobulin as it is secreted 2 Y s o IgD we don t know a lot about this one Monomer o IgE responsible for allergic reaction Monomer Haptens a molecule too small to be an antigen by itself In people with genetic allergies to a specific hapten it will bind to a protein carrier that is part of the self making a mega antigenic product Now antibodies probably IgE s will activate and proceed as usual If the hapten ever appears again even without binding to anything antibodies will be back via allergic reaction Antibodies How are these suckers made There are two pathways that can produce antibodies They can either be differentiated by T cells or B cells B in bone marrow T in the thymus o B Cell activation extracellular antigens roll into town B cells specific to certain antigenic epitopes are waiting for them An antigen fragment is taken into the cell then displayed on the surface of a MHC This B cell will then interact with a helper T cell specific to that eptitope which gives the B cell some cytokines B Cell is activated and begins clonal expansion producing plasma cells that will make moe antibodies o B cell will clone itself many times over before producing plasma cells o The antigens present initially are not active but are leftover chunks from phagocytosis o Some B cells will go in a different direction and produce memory cells which at a later date can be stimulated to become antibody producing plasma cells Anamnestic Response any response to an antigen after the primary response This is possible through memory B cells binds to two units o Agglutination reduces number of infectious units to be dealt with One antibody o Activation of complement two antibodies side by side on one unit will activate a complement that can lyse the cell o Opsonization Coating an antigen in antibodies as it enters a macrophage for phagocytosis o Antibody dependent cell mediated cytotoxicity antibodies attached to target cell cause destruction by macrophages eosinophils and NK cells no idea what this means o Neutralization multiple antibodies attaching to a bacteria or virus or toxin to prevent them from doing anything A thing to remember about adaptive immunity o Naturally acquired ie not through vaccines or anything Active antigens enter the body naturally body induces antibodies and specialized lymphocytes Passive antibodies pass from mother to fetus via placenta or mother s milk o Artificially acquired Active antigens are introduced in vaccines body produces antibodies and specialized lymphocytes Vaccines may be composed of killed or attenuated bacteria or viruses microbial components toxoids recombinant or nucleic acid Passive preformed antibodies in immune serum are introduced by ingestion Not used very often anymore but are used mainly to prevent