**2.2. Acquired immunity**

The acquired or adaptive immune response is the second line of defense mechanism which offer better protection against re-exposure to the same pathogen [2]. The acquired immune system is further subclassified into humoral mediated immunity which involves antibody production by B lymphocytes and cell mediated immunity comprising CD4+ and CD8+T lymphocytes. Acquired immunity has immunological memory and it is highly specific. The specificity occurs because each lymphocyte carries surface receptors for a single antigen [1]. When compared to innate immunity, it has slower response, however it is much more potent and robust and the response varies among individuals.

Innate and adaptive immune systems as well as complement counteract each other to produce an effective function and mechanism of eliminating the invading agents.
