1. Human Immunity Non-specific Immunity

2. Non-Specific Immunity  Non-specific = doesn’t distinguish between types of infectious agents  Innate  1 st line of defense = skin and mucous membranes  2 nd line of defense  Phagocytic cells  Inflammation (Sign that 2 nd line is working)  Complement system

3. 1 st line – Skin and Mucous Membranes  Physical barrier  Low H2O content  Secretions  Sebum, sweat  Stomach acid  Bile, duodenal enzymes  Lysozyme  Normal microbiota (microbiome)microbiome

4. 2 nd line – Phagocytosis *Limits spread of microbes in advance of specific response  Leukocytes = white blood cells  Neutrophils makes up 60-70% of leukocytes (chemotaxis)  Monocytes make up 5% of leukocytes. Circulate in blood and then become macrophages in tissues.  Macrophages engulf and digest with lysozyme in lysosomes.  Process of phagocytosis  Chemokines

5. Phagocytosis

6. 2 nd line -- Inflammation  Inflammatory response is an increased blood flow to the inured area resulting in leaking of fluid from capillaries into area causing swelling.  Rubor, calor, tumor, dolor  Triggered by chemical signals  from invader or host cells.  Basophils and mast cells release histamines.  Pus

7. 2 nd line -- Fever  Can provide non-specific defense against disease  Pyrogens  Produced by macrophages  Affect hypothalamus

8. 2 nd line – Natural Killer Cells  In blood and lymph  Use receptors to tell healthy cells versus cells with cancer or virus  Match with Class I MHC proteins (MHC = Major Histocompatibility Complex)  If not match, damage membrane and induce cell lysis

9. 2 nd line – Complement System

10.  ~30 proteins circulate in the blood and can be activated  Cascade of signals and proteins binding and hydrolyzing…  Classical Pathway - activated by the specific immune defense  Alternative Pathway – C3 protein binding directly to pathogen  Effects:  Activates inflammatory response  Acts as opsonin to increase phagocytosis (Opsonization)  Activates cascade to trigger MACs (Membrane Attack Complexes)  Large holes in membranes of gram – bacteria and enveloped viruses