Define Antigen and Antibody. Name any two diagnostic kits based upon them.
Antigen: A foreign substance, which elicits an immune response from the body, is called an antigen.
Antibody: A protein, which is synthesized in response to an antigen in the body, is called an antibody.
Two diagnostic kits; based on antigen and antibody are as follows:
(a) ELISA kit
(b) Pregnancy test kit