B cell T cell

T & B cells con't Humoral Immune Response: involves the activation and clonal selection of B cells. B cells produce antibodies the circulate the blood. Cell-mediated Immune Response: involves activation of cytotoxic T cells, which destroy infected cells. Helper T cells aid both responses. They secrete cytokines that activate B cells and cytotoxic T cells. (activated by MHCs Class II) Cytotoxic T cells: display antigenic fragments on the surfaces of all the infected cells. Bind to MHC Class I.

So... B CELLS make ANTIBODIES, which provide HUMORAL IMMUNITY, which fights PATHOGENS circulating in the blood. CYTOTOXIC T CELLS destroy infected body cells. HELPER T CELLS activate BOTH B & T CELLS.

RECALL: Activated B cells produce memory and plasma cells RECALL: Activated B cells produce memory and plasma cells. These circulate the blood to destroy the antigen. Types of antibody action: Neutralization: antibodies bind to pathogen surface proteins, preventing it from infecting more cells Opsonization: increased phagocytosis of the antigen Lysis Active Immunity: develops naturally as the bodies response to an infection (or artificially by vaccination). Eg- A microbe stimulates an immune response which results in memory cells being produced for that microbe. Passive Immunity: receives antibodies (eg- fetus receives them through the placenta)

Try THIS!! If a disease inhibits the helper T cells from working, what would directly occur as a result? Describe the long term effects. Do you know of a disease like this? Discuss.

DISEASE! Allergies are caused by antibodies attaching to receptors on mast cells (cells in many tissues that are rich in histamine and heparin granules). The next time the allergen enters, it binds to the mast cell, triggering the release of histamine. Lupus, rheumatoid arthritis and multiple sclerosis are all auto immune diseases, meaning the immune system attacks itself. HIV infects the helper T cells, suppressing the immune system.

Fun Facts Certain antigens on red blood cells determine your blood type MHC molecules are responsible for the rejection of tissue grafts and organ transplants. Pg 247 in Holtzclaw for details....

Three cheers for immune systems!!