The document discusses different types of antigens that can induce an immune response in the body. It describes exogenous antigens that enter the body from outside sources like viruses or bacteria, and endogenous antigens that are produced inside the body, including viral and tumor proteins. Endogenous antigens are further broken down into heterogenic antigens involved in tissue transplantation, allogenic antigens that occur between individuals of the same species, and autologous antigens that originate from within the body itself.

1.  Read and develop our knowledge

2. Its foreign molecule which induce the immune system in the
body.
It stimulates the lymphocytes to produce the antibody.
T-cell and B-cell are the antigen presenting cells.

3. Its majorly classified into two types
1. Exogenous antigen.
 Endogenous antigen.
 And endogenous antigen is fatherly classified into 3 types
1. Heterogenic antigen.
2. Allogenic antigen.
3. Autologous antigen.

4. This type of antigen are enter from the outside of the body.
This antigen entering site are macrophages, dentric cells etc.
Example: virus, bacteria and fungi etc.

5. These type of antigen found inside the cytosol of the human
cells.
Example: viral protein, tumer protein etc.
It was in three types.

6. It also known as xenogenic antigen.
It is foreign molecules related with the tissue
transplantation and serology at the time entering
molecule are heterogenic antigen.

7. This type of antigen occurs only in the
individual species.
For example blood group antigen.

8. The antigen originate from the body it self is
autologous antigen.
Example: Thyroglobulin and DNA etc.