Immune Response

Innate Immune Response

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The Immune System The immune system is a group of cells &

soluble molecules, which interact & distinguish patterns in the body as “self” or “non-self,” in order to eliminate those that are “non-self.”

“Non-self” entities include: Microorganisms, transplants, tumors, foreign

substances (eg: asbestos, particulate matter)

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The Immune Response To achieve its duty, the immune system has developed two

mechanisms: Innate immune response (IIR)

Non- specific

Adaptive immune response (AIR) Specific

Together, these two systems provide an efficient defense system

It makes it possible that although we spend our lives surrounded by germs, we sporadically get sick. Most infections are fixed successfully by IIR Other infections that IIR can not resolve, AIR will be triggered and

overcome successfully This is followed by lasting immunological memory

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Innate Immune Response (IIR) Is the first line of defense in the Immune

response Crucial to control of microorganisms growing

freely during early stage of IR Lacks memory It is NOT antigen (Ag) specific There are a limited recognition molecules Leads to the AIR

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Innate Immune Response (IIR)

Innate Immune Response

Surface (External) Barriers

SkinMucous membranes

Body secretions

Internal Defenses

PhagocytesNK cells

InflammationAntimicrobial

proteinsFever

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First line of defense

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IIR: External Barriers First line of defense against pathogenic “invaders”

Skin Largest organ in the body Produce lactic (low pH) & fatty acids, sweat, skin oils, which

make it difficult for microorganisms (MO’s) to survive When skin is injured, protects the body by way of inflammation

Mucus Mucosal membranes (mb) lining inner surfaces of the body

secrete mucus, which function as protective carbohydrate layer to stop bacterial invasion

Also traps and removes bacteria & particulate matter, by complementary action of cilliary movement, sneezing, coughing

Body secretions Washing actions of tears, saliva, and urine removes bacteria

and foreign particles from the body

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Natural or Innate Immunity: Inflammation When pathogenic agents penetrate external

barriers, the first reaction of the body is the inflammatory response Any time the cells or tissues of the body are

injured, internally or on the surface, by whatever agent, the inflammatory response occurs

Acute Inflammatory Response occurs in blood vessels near injury Acute Inflammatory Response helps leukocytes to leave

the blood vessel (diapedesis or emigration) & travel to injury site via chemotaxis

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Acute Inflammatory Response Chemotaxis- is the movement of cells in

response to a chemical attractant Interferon- if the cell injury is due to viral

infections, interferon, a protein that protects the body against viral infections is released

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Inflammation Cardinal signs of acute inflammation

Redness Heat Swelling Pain Impairment of function (sometimes)

Inflammatory mediators Histamine Blood proteins Kinins, prostaglandins, leukotrienes, and complement

Released by injured tissue, phagocytes, lymphocytes, basophils, and mast cells

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Acute Inflammatory Response Complement- a complex of interrelated and

interacting proteins manufactured in the liver

It is the major mechanism for destroying foreign substances

Active in inflammation and phagocytosis and also assists the action of antibodies in the specific response if the infecting agent is not destroyed by the nonspecific defenses

Figure 21.4, step 4

Innatedefenses

Internaldefenses

Leukocytosis.Neutrophils enter bloodfrom bone marrow.

Margination.Neutrophils clingto capillary wall.

Diapedesis.Neutrophils flatten andsqueeze out of capillaries.

Chemotaxis.Neutrophilsfollow chemicaltrail.Capillary wallBasementmembraneEndothelium

Inflammatorychemicalsdiffusingfrom theinflamed siteact as chemotacticagents.

1 2 3

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Phagocytosis

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IIR: Fever Systemic response to invading microorganisms Leukocytes and macrophages exposed to foreign

substances secrete pyrogens Pyrogens reset the body’s thermostat upward

High fevers are dangerous because heat denatures enzymes

Benefits of moderate fever Causes the liver and spleen to hold iron and zinc

(needed by microorganisms) Increases metabolic rate, which speeds up repair