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Second Line of Defense
The second line of defense is nonspecific resistance, also classified as innate immunity, which destroys invaders in a generalized way without targeting specific individuals.
1. Phagocytic cells
- Example - macrophages are cells derived from monocytes that leave the bloodstream and enter body tissues to patrol for pathogens (they are like the police on the street looking for law breakers). When the macrophage encounters a microbe, it engulfs it and displays the pathogen antigens on its cell surface at the major histocompatibility complex or MHC proteins on cell surface that can bind to foreign antigens for display sites on the cell.
- The macrophage will also release interleukin-1 which raises body temperature and activates T cells to release interleukin-2.
2. Inflammation (or Inflammatory Response) is a localized tissue response that occurs when your tissues are damaged and in response to other stimuli. The damaged cells release chemicals including histamine, bradykinin, and prostagladins. These chemicals cause blood vessels to leak flouid into the tissues, causing swelling. Inflammation brings more white blood cells to the site where the microbes have invaded in order to heal. the inflammatory response produces swelling, redness, heat, and pain.
3. Fever inhibits bacterial growth and increases the rate of tissue repair during an infection. It also, increases the production of WBCs.
Check for understanding:
-Is the second line of defense considered to be an innate or adaptive immune response and why?
-What are the three modes of action of the 2nd line of defense?
