NON-SPECIFIC HOST DEFENSE

First line of defense 

Skin

Mucous membrane

Factors that accounts for the skin’s ability to resist pathogens 

1. Dryness of most areas of skin inhibits colonization by many pathogens.

2. Acidity and temperature of skin inhibit the growth of pathogens

3. Oil sebum produce fatty acid which is toxic to some pathogens.

4. Perspiration- contain enzyme LYSOZYME, which destroy peptidoglycans in bacterial cell.

5. Soughing dead skin remove pathogens.

Mucous 

       Lysozyme 

-            destroy peptidoglycan of cell.

       Lactoferrin 

-            binds iron (which needed by pathogen and deprived by this)

       Lactoperoxidase 

-            produces superoxide radicals highly reactive forms of oxygen which are   toxic to bacteria. 

Digestive Tract 

1.        Digestive enzymes

2.        Acidity of stomach

3.        Alkalinity of intestine

4.        Bacteria trapped in mucous lining and destroyed by enzyme. 

Urinary Tract 

1.                  Frequent urination flushed microorganism from urethra. 

2.                  Respiratory System 

3.                  Cilia

4.                  Lysozyme (saliva)                        human swallow approximately 1 liter of saliva per day. 

Microbial Antagonism 

1.      Normal flora prevent other organism in colonization to a particular site. 

2.      Inhibitory capability of the indigenous microflora  3. Competition for colonization site

4.      Competition for nutrient.

5.      Production of substance that kill other bacteria 

.

Inflammation 

-     Response to any local injury, irritation,  microbial invasion or bacterial toxin  by   a complex series of events 

Cardinal Signs of inflammation 

1.      Redness

2.      Heat

3.      Swelling

4.      Pain

Major events in acute inflammation 

1.      Increase diameter of capillaries 

2.      Increase permeability of capillaries, allowing escape of plasma and plasma proteins.

3.      Exit of WBC from the capillaries and their accumulation at the site of injury. 

Sequence of events of inflammation

1.      Tissue injury

2.      Vasodilatation

3.      Increase permeability

4.      Emigration of WBC

5.      Chemotaxis

6.      Phagocytosis

Primary purposes of inflammatory response 

1.      Localize an infection

2.      Prevent the spread of microbial invaders.

3.      Neutralize any toxins being produced at the site.

4.      Repair of damaged tissue 

Terminologies 

Inflammatory Exudates

-      accumulation of fluid cells, and cellular debris at the inflammation site. Pyocyanin

-      bluish green pigment.

Pus

-      yellow, thick greenish containing any live and dead WBC.

Phagocytes 

-      phagocytic WBC

Phagocytosis 

-      process by which phagocytes surround and ingest foreign materials. 

•      Professional Phagocytes 

•      Macrophages

•      Neutrophils 

•      Macrophages 

          Developed from monocytes during the inflammatory response to infection.

                        Types:

a.      Wandering Macrophages- those that leave the B.V. and migrate to  infected area.

b.      Fixed Macrophages-  known as histiocytes.

                                           - remain in tissues and organ to trap foreign debri.

Reticuloendothelial System 

        -macrophages are found in its tissue.

        -found in cells in:

1.    Liver (Kupfer  Cells)

2.    Spleen

3.    Lymph nodes

4.    Bone marrow

5.    Lungs (Alveoli)

6.    Blood vessels

7.    Intestine

8.    Brain  (microglia)

                     -removal and engulfment of debrie, dead cells and microorganism. 

Chemotaxis 

          Attraction of phagocytes to the site  where it is needed.

        •     Chemotactic  agents-  chemical attractants 

4 steps in Phagocytosis 

1.      Chemotaxis

2.      Attachment

3.      Ingestion

4.      Digestion

5.      Chemokines      chemotactic agents that are produced by the various cells of human body. 

Attachment 

        -phagocytes can only ingest objects to which they can attach. 

Ingestion 

        -Pseudopodia surrounds the object  àINGEST 

Digestion        object is broken down and dissolved by digestive enzymes and other. 

Second line of defense 

1.      Transferrin

2.      Pyrogen

3.      Interferrons

4.      Complement system

5.      Acute phase

6.      Cytokines

Transferrin 

-Serves as defense by requesting iron and depriving pathogens of this essential nutrients. 

Pyrogens 

-            Stimulate the production of fever.

                        Ex.  Interleukin 1 (11-1)

                  fever will augments host defenses by:                                 a.  Stimulate WBC

b.    Reduce available free plasma iron

c.     Induce production of IL-1 which causes the proliferation, maturation                                        and  activation of lympocytes in the immunologic defenses. 

Interferons 

-            interfere with viral replication:

      Three  types:

a.    Alpha ( OC )- produce by: B lympocytes, monocytes, macrophages.

b.    Beta-  produced by fibroblast and other virus infected cells.

c.     Gamma (Y)- produced by activated T Lympocytes, Natural killer cell.

Complement System

-            Group of proteins that is complementary to the action of immune system.

-            Small, antiviral protein produced by virus (infected cell)

-            Specific, effective against a variety of viruses, not just a particular type of viruses.

-            Complement Results 

-            Initiation and amplification of inflammation

-            Attraction of phagocytes to the sites where they are needed.  (Chemotaxis)

-            Activation of leukocytes

-            Lysis of bacteria and other foreign cells. 

Acute Phase Protein 

-            Increase rapid response to infection, inflammation and tissue injury.

                   Include:

a.    C-reactive protein 

b.    Serum amylad A protein

c.     Protease inhalators

Cytokines 

-            Chemical messenger between immune system (with in)  and immune system and other system of the body.