Disorders of Immune Reaction-Definition Terms

The antigen is a foreign protein substance that can evoke an immune response mediated by plasma cells .
The incomplete antigen is a nonprotein foreign substance that can evoke an immune response by combining whit one of the body proteins (where this combination acts as an antigen).
When a tissue structure is considered antigenic is called autoantigen and leads to an autoimmune disease.

The antibodies are proteins secreted by plasma cells,called immunoglobulins.

Immunity-is a useful reaction against living irritants resulting in their elimination.
Hypersensitivity-a hurmful reaction against living irritants (bacteria,virus,etc) or non living irritants (such as food proteins,dust,pollens,drugs,etc) leading to tissue destruction.

STEM CELLS - Sources and Therapeutic Applications

Stem cells exist in various parts of the human body at every stage of development from embryo to adult.
They are the master cells of the body.They are unspecialized cells that can divide giving copies of themselves and under proper conditions can alo develop into mature cells of different types such as liver cells,nerve cells,skin,pancreatic insulin producing cells,cardiac muscle,vessels and many others.The recent exhaustive researches about stem cells prove that these cells can be ued in repairing,treating and curing a variety of diseases and injuries.
Also a number of recent experiments have raised the possibility that stem cells from one tissue may be able to give rise to cell types of a completely different tissue.This phenomenon is known as stem cell plasticity.
Exemples of such plasticity include bone marrow stem cells becoming neurons or pancreatic islet cells that are capable of producing insulin.

Sources of STEM CELLS:
Stem Cells can be colected from:
-aborted fetuses or IVF embryos (fertilized eggs)-but it is a etthical utility
-bone marrow
-peripherial blood
-umbilical cord blood
-skin
-pulp of milk teeth
-and fat cells are recnt sources of adult stem cells

Therapeutic Applications of STEM CELLS:
-Generation of different types of neurons for the treatment of Alzheimer's disease
-Spinal Cord Injuries
-Parkinson's disease
-Generation of insulin-secreting pancreatic islet cells to treat type I Diabetes
-Production of heart muscle cells to repair myocardial injury
-Generation of hair folicle stem cells for the treatment of certain types of baldness
-Drug testing
-Cancer research
-Research on embryonic development.