Chapter 21: T cells – Flashcards

-Plays a central role in adaptive immune response -Activate both humoral and cellular arms -Once primed by APC presentation of antigens, they help activate T and B cells, induce T and B cell proliferation, their cytokines recruit other immune cells -Amplifies the immune response of the innate immune system -Activate macrophages (more potent killers) -Mobilize lymphocytes and macrophages, and attract other types of WBCs

-No immune response

-Helper T cells binds with the self-nonself complexes of the B cells that has encountered its antigen and is displaying it on MHC II on its surface -Interact directly with B cells displaying antigen fragments bound to MHC II receptors

-Helper T cells releases interleukins as co-stimulatory signals to complete B cell activation -Stimulate B cells to divide more rapidly and begin antibody formation

-Yes, can bind to T cell-independent antigens -Response is weak and short lived

-T cells that activate B cells

-Helper T cell binds to dendritic cells -CD8 cells require helper T cell activation into destructive cytotoxic T cells -Causes dendritic T cells to express co-stimulatory molecules required for CD8 cell activation

-Helper T cell stimulates the dendritic cells to express co-stimulatory molecules

-Dendritic cells can now activate CD8 cell with the help of interleukin 2 secreted by T cells

-Directly attacks and kills other cells -Activated T cells circulate in blood, lymph, and lymphoid organs in search of body cells displaying antigens they recognize

-Cytotoxic T cells binds specific membrane receptors on target cells, and stimulates apoptosis -Cytotoxic T cells releases perforins and granzymes by exocytosis (perforins create pores through which granzymes enter target cells: granzymes stimulate apoptosis)

-Cytotoxic T cell identifies foreign antigens on MCH I proteins and binds tightly to target cell

-Cytotoxic T cells releases perforin and granzymes molecules from its granules by exocytosis

-Perforin molecules insert into the target membranes, polymerize, and form transmembrane pores (cylindrical holes) similar to those produced by complement activation

-Granzymes enter target cells via the pores -Once inside, granzymes activate enzymes that trigger apoptosis

-Cytotoxic T cell detaches and searches for another prey

-Acquired Immune Deficiency Syndrome

-Caused by human immunodeficiency virus (HIV)

-Can enter the body through blood transfusions, blood contaminated needles, sexual intercourse and oral sex, mother to fetus

-Cripples the immune system by interfering with the function of helper T cells

-Opportunistic infections -Virus also invades the brain -> dementia

-Antivirals

-The immune system loses ability to distinguish between self and nonself

-Production of autoantibodies and sensitized helper T cells that destroy the body tissues

-Multiple Sclerosis -Myasthenia gravis -Type 1 diabetes -Hashimotos's disease -Rheumatoid arthritis

-Suppress the entire immune system