Three of such principal cells of the immune system are lymphocytes, antigens, and effector cells. Below, brief descriptions of the roles of these three cells in immune response are discussed.
Lymphocytes have been noted to be cells that emanate from stem cells within the larger immune system. As far as immune response is concerned, the lymphocytes take charge of the adaptive response (Guermonprez et al., 2012). For this to happen, there are a series of functional activities that come together. Working together with specific receptors, the lymphocytes function towards the recognition of specific antigens that enter the body. Consequently, the effect of antigens in the body would be hampered if the lymphocytes are not functioning properly. Bryant, Trinder and Curtis (2004) also noted that one the lymphocytes emanate from the stem cells, they go on to form three different populations of cells which are B cells, T cells and natural killer (NK). Of the three however, it is the B and T cells that take part in the adaptive immunity as NK cells function as innate immunity. The B cells for example produce antibodies, whiles the T cells engage in cell-mediated immunity (Guermonprez et al., 2012).
The second principal cells are the antigen presenting cells, which have the core role of aiding the lymphocytes to undertake the adaptive response. In some cases therefore, the antigen presenting cells are considered to be also responsible for adaptive response. The antigen presenting cells function by bringing antigens to the lymphocytes. Writing on the anatomy of the immune system, Zen and Parkos (2003) indicated that the location of the antigen presenting cells (APC) makes it very convenient for it to play its role. This is because these APCs are found in the periphery. From this location, they are able to examine the tissues to identify antigens.