Antigens are molecules capable of stimulating an immune response. Each antigen has distinct surface features, or epitopes, resulting in specific responses.
Antibodies (immunoglobins) are Y-shaped proteins produced by B cells of the immune system in response to exposure to antigens. Each antibody contains a paratope which recognizes a specific epitope on an antigen, acting like a lock and key binding mechanism. This binding helps to eliminate antigens from the body, either by direct neutralization or by ‘tagging’ for other arms of the immune system.
Comparison Chart on Differences Between Antigen & Antibody
Substance that can induce an immune response
Proteins that recognize and bind to antigens
Usually proteins, may also be polysaccharides, lipids or nucleic acids
Within the body or externally
Within the body
Specific binding site
The Role of Antigens & Antibodies in Vaccinations
Vaccines contain antigens which stimulate the B lymphocytes of the immune system to respond by producing plasma cells which secrete disease specific antibodies (Primary response). Some of the B cells become memory B cells, which will recognise future exposure to the disease. This results in a faster and more intense production of antibodies, which effectively work to eliminate the disease by binding to the antigens (Secondary response).