Specialization in Adaptive Immunity

Adaptive immunity evolved to deal with the cornucopia of pathogenic microbes that are present in the environment. Randomization of immune receptors and division of labor among highly specialized immune cell subsets were both key steps in the development of an immune system that could distinguish each unique microbial threat in a sea of potential threats. B cells recognize microbial pathogens through a randomly rearranged antigen receptor and begin to produce soluble antibodies that may affect the removal of microbes from the host. B cells can differentiate into long-lived cells that continuously produce antibodies that protect the host from future microbial threats and are capable of tailoring their activity to a specific threat by modifying the type or quality of antibody they produce. In a similar manner, specialized subsets of T cells developed that could seek out and destroy intracellular pathogens that were hidden from antibodies, while yet other subsets of helper cells produce specific cytokines to modulate the humoral and cell-mediated immune responses of the host. This specialization permits the immune system to stock a limited number of sentinel cells that can sense infection and differentiate into a variety of distinct cell lineages individually suited to perform the necessary antimicrobial tasks.