Hum

an Im

mun

ityNon-specific

Imm

unity

Non-Specific Immunity Non-specific = doesn’t distinguish between types of infectious

agents Innate

1st line of defense = skin and mucous membranes

2nd line of defense Phagocytic cells Inflammation (Sign that 2nd line is working) Complement system

1st line – Skin and Mucous Membranes Physical barrier Low H2O content

Secretions Sebum, sweat Stomach acid Bile, duodenal enzymes Lysozyme

Normal microbiota (microbiome)

2nd 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

Phagocytosis

2nd 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

2nd line -- Fever

Can provide non-specific defense against disease

Pyrogens Produced by macrophages Affect hypothalamus

2nd 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

2nd line – Complement System

2nd line – Complement System ~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