White blood cells

[Ref: WG21:p518-523]

Normal level
= 4000 to 11000 per microliter

Composition of WBC population

Granulocytes (polymorphonuclear leukocytes, PMNs) are the most numerous
* Includes neutrophil, eosinophil, and basophil

• Neutrophil
  * Neutrophilic granules
  * 50-70% of WBC
  * N = 3000-6000 per microliter
• Eosinophil
  * Granules stain with acidic dye
  * 1-4% of WBC
  * N = 150-300 per microliter
• Basophil
  * Granules stain with alkaline dye
  * 0.4% of WBC
  * N = 0-100 per microliter

Lymphocytes
* Large round nuclei and scanty cytoplasm
* 20-40% of WBC
* N = 1500-4000 per microliter

Monocytes
* Kidney-shaped nuclei
* Agranular cytoplasm
* 2-8% of WBC
* N = 300-600 per microliter

 

 

Granulocytes

Neutrophil

Halflife = 6 hours

100 billion neutrophils are produced daily

Many neutrophils enter the tissues
* Attracted to endothelial surface by selectins
--> Roll along the surface
--> Binds firmly to neutrophil adhesion molecule (of the integrin family)
--> Squeezes through the walls between endothelial cells by a process called diapedesis

Inflammation

During inflammation, large numbers of neutrophils are produced and released from bone marrow

Neu

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Stopped at WG21:p520

@@ Will finish after viva and after reading some decent immunology book. WG is too brief!!!

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Principal opsonins that coat the bacteria = IgG and complement proteins

 

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IL-4 = Basophil differentiation

IL-5 = Eosinophil differentiation

 

IL-1, then IL-6, then IL-3, act to commit pluripotential uncommitted stem cells to committed progenitor cells

 

IL-1, IL-6, and TNF-alpha --> fever

IL-1 reduce appetite

=====

[WG21:p526]

Complement system

1. Opsonization, chemotaxis, lysis of cells
2. Activate B cells and aiding immune memory
3. Help dispose of waste products after apoptosis

 

=====

[WG21:p527]

TH1 cells secrete IL-2 and gamma-interferon
--> Primarily cellular immunity
* IL12 encourage TH1 formation

TH2 cells secrete IL-4 and IL-5
--> Interact primarily with B cells (humoral immunity)
* IL4 encourage TH2 formation

 

IL1
* From macrophages
* Activate T cells and macrophages

IL2
* From TH1 cells
* Cause activated T cells to proliferate (autocrine) [WG21:p529]
* Activate lymphocytes, NK cells and macrophages
* Inhibited by glucocorticoids

 

Gamma Interferon
* From TH1 and NK cells
* Activation of macrophages
* Inhibit TH2 cells

 

Cytotoxic T cells = CD8 (heterodimer)
* Binds to MHC-I

T helper cells = CD4 (single protein)
* Binds to MHC-II

 

Class I MHC proteins = coupled to internally synthesized proteins (e.g. viral proteins)
* Cytotoxic T cells (CD8)

Class II MHC proteins = targets extracellular antigens (e.g. bacteria) that enter the cell by endocytosis and digested
* T helper cells (CD4)

 

Class I antigen = ALL nucleated cells

Class II antigen = present in antigen-presenting cells (B cells and activated T cells)

 

=====

[WG21:p530]

Functions of immunoglobulin

• Neutralising some protein toxins
• Blocking attachment of some viruses and bacteria to cells
• Opsonizing bacteria
• Activating complement system

 

Central tolerance occurs in the thymus for T cells, the bone marrow for B cells