Classification of Antigen, T- dependent antigen and T- Independent antigen

T- Dependent antigen


The consequences of antigen contact with RBC depend on the types of antigen or nature of antigen and signals received by the B cells. Contacting antigen alone is not enough to activate B cells because nearly all protein antigen need antigen specific T cell help to generate an antibody response. Basically immune response to all most all the antigens depend on both T cells and B cells understanding the antigen in a related fashion. This type of antigen is called T-dependent antigen (TD-Ag).

T- Independent antigen  

Several  antigens do not require the presence of helper T cells, they are called T- independent antigen or TI-Ag. They can be classified into two categories.
1  TI-1 group, at high concentration induce activation of many B cells both specific and non specific.
2  TI-2 do not have polyclonal cell activator properties, nor do they activate macrophages. These antigens are highly repetitive polymetric antigens such as polysaccharides from bacterial cell wall. 

Classification based on Relationship with Host

Heterophilic Antigen

It is a type of common antigen present in human, animals and microorganisms.

Xenogenic Antigen

Xenogenic Antigen
This antigen comes from different genus and generic. The important xenogenic antigen are pathogenic microorganisms, plant proteins, animal serum.

Allogenic Antigen

A specific antigen that exists in different individual of same genus. The important human allogenic antigen include
  • Red cell blood type antigen
  • Rh antigen system  et al
  • Human leukocyte antigen

Auto Antigen

A tissue constituent that usually induce an immune response to the host's tissues

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