INNATE IMMUNITY

INNATE IMMUNITY

1. non-specific defense where no recognition of the pathogen

   • fully functional without previous exposure to invaders
     • occurs immediately

2. 4 types of innate immunity

   • 1. Physical and chemical barriers (1st line defense)
     • 2. The inflammatory response (2nd line defense)
       • 3. Phagocytes and natural killer cells
         • 4. Protective proteins

3. 1. Physical and chemical barriers

   • - skin - mucus by mucous membrane ensnares microbes - ciliated cells in respiratory tract sweep mucus - lysozyme lyse bacteria - acidic pH in stomach inhibits microbes

4. 2. inflammatory response

   • - tissues are damaged - signs : 1. redness 2. heat 3. swelling 4. pain
     • - injured tissue cells & mast cells release histamine causes capillary to become more permeable - inflamed area exhibits redness, heat, swelling and pain - WBC migrate to the injured tissues - macrophages & dendritic cells release cytokines that stimulate inflammatory response & phagocytize pathogen - they squeeze thru the capillary wall & phagocytize pathogen - blood clotting forms to seal break in blood vessel

5. 3. Phagocytes and NK cells

   • 1. neutrophils - phagocytize bacteria - have antimicrobial peptides & bacteria-digesting enzyme in cytoplasm - kill engulf bacteria with free radicals
     • 2. eosinophils - phagocytic cells - mount on parasite that are too large to be phagocytized
       • 3. macrophages & dendritic cells - engulf pathogens - stimulate T cells
         • 4. Natural killer cells (NK) - large, granular lymphocytes - kill virus-infected cells and cancer cells - NK cell recognize that these cells lack of MHC-I - NK cell induce them to undergo apoptosis

6. 4. Protective proteins

   • 1. Complement - composed of plasma protein that "complement" certain immune responses - activated by pathogens - destroy pathogen in 3 ways : enhanced inflammation : increased phagocytosis : membrane attack complexes
   • 2. Interferons - cytokines that affect behavior of other cell - produce by virus-infected cells - bind to the receptor of non-infected cell causing them to produce substance that slow cellular metabolism & interfere with viral infection