Immunology

• Natural killer cells


  Part of innate immune system, easily kill virally infected cells and tumor cells
• Natural killer cells


  • Distinguish infected cells and tumors from normal and uninfected cells by recognizing changes of a surface molecule called MHC (major histocompatibility complex) class I
  • Activated in response to a family of cytokines called interferons
  • Release cytotoxic (cell-killing) granules which then destroy the altered cells that miss the MHC class I
• B cells


  Grow to maturity independent of the thymus
• T cells


  Developed and mature in the thymus
• B cell response to foreign material (antigens)

  1. Differentiate into plasma cells

  2. Plasma cells produce immunoglobulins (antibodies)

  3. Antibodies neutralize foreign objects like bacteria and viruses

  4. Antibodies find their way into the bloodstream, tissues, respiratory secretions, intestinal secretions, and even tears
• B cell memory


  1. cells can mature into memory cells, which allows a rapid response if the same infection is encountered again
• Plasma cells


  Developed from B-cells, responsible for making immunoglobulins
• T cells


  Also called T-lymphocytes, often named in lab reports as CD2 cells, develop from hematopoietic stem cells in the bone marrow
• T cell mediated immunity


  Also called cell mediated immunity
• Natural Killer (NK) cells


  A type of white blood cell that plays a crucial role in the body's immune system, helping to protect the body against viruses and cancer
• MHC (major histocompatibility complex) class I


  A surface molecule found on most cells in the body, whose function is to display pieces of protein from inside the cell to the outside, allowing the immune system to monitor the health of cells
• Infected cells and tumors

  May reduce or alter the display of MHC class I molecules, which is a signal to the immune system that something is wrong
• Interferons


  A family of cytokines (signaling molecules) that are released by infected cells or by immune cells in response to infection, and activate NK cells
• Cytotoxic (cell-killing) granules


  When NK cells find a cell with altered MHC class I molecules, they release cytotoxic granules that contain proteins called perforins and granzymes, which enter the target cell and trigger programmed cell death, effectively destroying the altered cell