Cellular immune responses, through both T and B cells, are critical to understanding the role and regulation of lymphocytes following viral infection, as well as defining responses to vaccination. T cells play a critical role in adaptive immunity, including pathogen elimination through the engagement of CD4 and CD8 receptors, which trigger signaling mechanisms. B cells contribute to generating antibodies following exposure to foreign pathogens through interactions with CD4+ lymphocytes. While these different cell types have distinctly different modes of action in terms of contributions to protection (cytotoxic versus antibody mediated), they account for the majority of adaptive immunity induced following infection or vaccination. While the ability to measure cell-mediated immunity (CMI) has steadily improved, there is much to learn with regard to their contribution to the protection of birds against diseases induced by avian influenza virus. The rapidly increasing knowledge of genomic avian sequences, along with the increasing availability of monoclonal antibodies detecting avian cell-associated antigen markers, has made techniques to measure CMI more specific and informative for researchers.
Keywords: Avian influenza; Avian lymphocytes; Cell-mediated immunity; Cytokines; Cytotoxicity; ELISPOT; Flow cytometry; Proliferation.