Specific or adaptive immunity comes into action when a pathogen passes the first line of defense and it helps fight and eliminate a particular Antigen (a term with which you designate any substance recognized as foreign to the organism that is trying to get an immune reaction).

This is based on the action of antibodies, special blood proteins that recognize specific foreign substances, and lymphocytes, the cells present in the blood and other tissues, which are a form of T or B lymphocytes, that then activate and regulate the immune response, as well as detect and destroy foreign material. They produce specific antibodies and memorize the identity of the invader, to ensure a quicker response in the event of a later attack.