Description:
The human body has two first lines of defense against harmful pathogens andtoxins. First, there are antimicrobial substances that kill bugs andtoxins; these substances are in saliva and nasal secretions. When anorganism gets past this defense, the inflammatory response reacts, releasinghistamine and calling white blood cells to the injury site, causing swelling.One of the body's immune mechanisms involves a substance known as interferon.Cells which have been invaded by viruses release interferon, hitting receptorsites on adjacent cells, which produce antiviral enzymes preventing virusreplication. Recombinant DNA techniques allow us to easily make interferon.Another semispecific immune response is a blood protein known as complement.These immune responses, as well as B and T cells, are different from thenon-specific response in that they target only one specific type of pathogenat a time, instead of hitting anything that moves, as do phagocytes.In the highly-specific responses lie antibody-mediated and cell-mediatedimmunity. Cell mediated immunity works through T cells and macrophages,while antibody-mediated immunity uses helper T cells and B cells.AIDS, by the way, works by blocking the immune system response, so that anAIDS victim is victim to other infections that the immune system usually kills. |