The adaptive immune response is mediated by lymphocytes. Its hallmarks are a high specificity for distinct antigens and an immunological memory.
An adaptive immune response is stimulated by exposure to infectious agents or their products. It is mediated by T and B lymphocytes. Through their differentiation, an immunological memory is established. Repeated exposure to the same antigen will then lead to a faster and more vigorous immune response. This is also the principle behind vaccinations.