Specific Immunity If a pathogen enters the body, the non-specific defenses (innate immunity) are activated (discussed above); concurrently, the specific defenses (acquired immunity) are also stimulated. Once activated, the specific immune system mounts a defense that is specific to the invader, global , and long-lasting . The B- and T-lymphocytes mediate the specific response to pathogen infection; they work together but utilize different mechanisms to destroy invading pathogens. The majority of circulating lymphocytes are T-cells while B-cells comprise about 15% of the total. NK cells are about 5% of the total lymphocytes. T-cells are responsible for a cell-mediated defense while B-cells produce antibodies to protect the body. Clonal Selection An important aspect of specific immunity is the principle of clonal selection. Only those B- or T-lymphocytes that have been activated by antigen exposure will proliferate . After proliferation, the clones differentiate into plasma, cytotoxic, memory, etc. lymphocytes.
This is the end of the preview.
access the rest of the document.