Factors influencing the antigenicity of antigens
Antigen must be a foreign substance as more foreign the substance, the more immunogenic in nature. However the following factors can also influence it,
1. The antigenic response which is indicated by the quantum of antibody formed in response to antigenic stimulation varies depending on the dosage of antigenadministered, route of administration and use of adjuvant etc.
2. Molecular weight of the antigen affect the antigenicity as low molecular antigenscan only combine with the antibody (hapten).
3. Very low molecular weight substance cannot act as an antigen. Because of this the virus which has the very low molecular weight proteins escapes the immune response.
4. Very large molecular antigen directly induces the B cell differentiation with out the involvement of T Cells.
5. Degradability is essential as in the antigen presenting cells process the antigenby degrading them and processed peptide antigen along with the MHC II molecule presented to the T cells and such antigens are called T dependent antigen.
6. Antigen induced antibody response can be suppressed by administrating the antibody passively either prior to or shortly after administration of antigen (This is utilized for the treatment of Rh antigen induced antibody in the mother leading to Erythroblastosis fetalis).