Nonspecific Immunity

What is non specific immunity? Protects regardless of pathogen Includes first and second line of defense –We’ll discuss third line in another lecture!

First line of defense

What is the first line of defense? Physical barriers Chemical barriers Normal Microbiota

What are physical barriers? Skin –Epidermis Many cells packed tightly Keratin Arid Benign microbes sloughing –Dermis Infections most likely from –Subcutaneous staphylococci

What are chemical barriers? Lysozyme Mucous membranes Lacrimal apparatus Saliva Mucociliary escalator Epiglottis Urine Vaginal secretions Lactic acid mantle

Normal Microbiota Microbial antagonism/competitive exclusion: Normal microbiota compete with pathogens. –Candida albicans –E.coli –Salmonella –Shigella

Second line of defense

What constitutes the second line of defense? Phagocytosis Inflammation Complement Interferons

What are phagocytes? Literally means ___________ All are leukocytes Neutrophils Leukocytes Monocytes –Macrophages Eosinophils Basophils

How do phagocytes work? Adherence Phagosome Phagolysosome

Does phagocytosis always work? Nope! Adherence inhibition –Streptococcus pyogenes M protein –Capsules also H pylori, Streptococcus pneumoniae Ingested but still alive –Staphylococcus leukocidins –Streptococcus streptolysin Staphylococcus

Does phagocytosis always work? Mycobacterium tuberculosis, HIV, Chlamydia, Plasmodium –Prevents fusion and acidification of enzymes –Multiply within phagocyte Chlamydia inclusion on pap smear cell

How do leukocytes get to a wound? Diapedesis Chemotaxis

What about inflammation? Pain Redness Swelling Heat Acute inflammation –Boil: S. aureus Chronic inflammation –M. tuberculosis

What is fever? Pyrogens –Exogenous Some viruses, endotoxins –Endogenous Interleukin I Inhibits pathogens Reduces iron availability Stimulates immune response

The Complement System Serum proteins activated in a cascade. Figure 16.9

Effects of Complement Activation Opsonization or immune adherence: Enhanced phagocytosis. Membrane attack complex: Cytolysis. Attract phagocytes. Figure 16.10

Effects of Complement Activation Figure 16.11

What happens with complement? –20 subunits –Cascade reaction –Classic pathway Binding to mannan stimulates –AnimationAnimation

What happens with complement? –20 subunits –Cascade reaction –Lectin pathway Binding to mannan stimulates –AnimationAnimation

What are interferons? Antiviral –Induce antiviral protein production –Causes neutrophils and macrophages to phagocytize bacteria. –animationanimation