Question

What are 3 antigen classifications AND their combinations (don't worry about Rh factor(+)).

Answer 1

1. Blood typing

Under the ABO blood group system, the types of antigen present are A-antigen and B antigen., antigen H which remains absent in the Bombay blood group, this blood group is often confused with the O blood group.

The different combinations with these antigens possible are: A+, A-, B+, B-, AB+, AB-, O+, O-, hh (Bombay phenotype)

Other classification systems include-

2. Antigens can be classified on the basis of their Origin

1. Exogenous antigens

• The antigens usually enters through phagocytosis and starts circulating in the body fluids. They are trapped by the antigen processing cells. Eg: bacteria, viruses, fungi, etc

2. Endogenous antigens

• These are the body’s own cells or compounds that are processed by the macrophages and presented to the immune system by the cytotoxic T – cells. Eg. Blood group antigens, HLA.

3. Autoantigens

Autoantigens are complex of proteins that are often recognized by the body’s immune system which eventually leads to autoimmune disorders. Eg. Nucleoproteins

3. Antigens can be classified on the basis of the immune response

1. Complete Antigen is proteins or polysaccharides in nature and is able to produce an immune response by themselves.

2. Incomplete Antigen or Hapten is the foreign substance, that is unable to induce an immune response on its own, they require carrier molecule to perform as a complete antigen.