Lecture 11 Block 3 Flashcards
(30 cards)
what are the epitopes of antigens
recognition sites for B or T cells
what is B cell and T cell specificity
antigen receptors on the surface of T or B cells recognize specific antigens/epitopes
what is clone selection
an antigen interacts with lymphocytes that have corresponding antigen receptors and induces proliferation and differentiation of those lymphocytes
what are the two types of clones that activated lymphocytes can develop into
short lived effector cells that combat the antigen and long-lived memory cells that memorize specific antigens
what is self tolerance
As B and T cells develop, those that have antigen receptors against normal body cells are destroyed by apoptosis
what is humoral immunity
the aspect of immunity that is mediated by macromolecules found in ECF such as secreted antibodies, complement proteins, and certain antimicrobial peptides. it defends against bacteria, toxins, and viruses in body fluids
what is B cell mediated humoral immunity
B cell exposure to antigen tiggers clonal selection to produce memory B cells and plasma cells
what are plasma cells and what do they do
secrete 2000 antibodies specific for antigen per second, they can circulate several weeks, binding to and marking antigen for destruction
what are T dependent antigens (proteins)and what do they do
induce production of both plasma cells and memory B cells. it requires that helper T cells release cytokines in response to specific antigen.
what do IL-2 and T-dependent antigens do
activate B cells to produce plasma cells and memory B cells
what do T-dependent antigens (polysaccharides) do
activate B cells to produce plasma cells. T-dependnet antigens do not activate Helper T cells to release IL-2 , without helper T-cells releasing IL-2, proliferating B cells do not develop into memory B cells
what are antibody functions
- neutralization
- agglutination
- opsonization
- complement activation
- enhancing activation of NK cells
what does neutralization do
binding of antibody can block the activity of some pathogens
what happens in agglutination
cross-binding of antibody and pathogen can link and clump pathogens together
what happens in opsonization
binding of antibodies to a pathogen facilitates phagocytosis of the pathogen
what happens in complement activation
IgM and IgG can activate complement system through the classic pathwat
what happnens in enhancing activation of NK cells
IgG tails can bind to receptors on the surface of NK cells and allow NK cells to specifically attack antibody marked cells
what is cell-mediated immunity
mediated by T cells and involved lysis of cells by cytotoxic T cells, it defends against bacteria and viruses in body cells
what are the types of T lymphocytes
Helper T cells, cytotoxic T cells and suppressor T cells
what do helper T cells do
secrete cytokines that enhance activity of B cells and other T cells
what do cytotoxic T cells do
kill cells infected by virus or bacteria and other abnormal cells
what do suppressor T cells do
secrete cytokines that suppress activity of B cells and other T cells
what is the major histocompatibility complex
a set of cell surface proteins essential for the specific immune system to recognize foreign molecules
what is antigen presentation
MHC binds antigen within the cell and transports it to the surface of the cell where it can be recognized by T cells
