ch. 43 part 2 Flashcards
cytokines are released from the ________ to activate the helper T cell
macrophage/dendritic cell
activation of B cell in humoral response
- entered antigen taken in by receptor-mediated endocytosis
- MHC 2 presents antigen on B cell surface
- activated helper T cell recognizes antigen and releases cytokines
- activated B cell divides into memory and plasma cells
plasma B cells
secrete antibodies that go out and identify/mark foreign pathogen
how many antibodies does each plasma cell release
over a trillion over 4-5 days
- 2,000 per second
what do antibodies do
mark pathogens for inactivation/destruction
- don’t kill them
3 processes performed by antigens
- neutralization
- opsonization
- antigen-antibody complex
- agglutination
- precipitation
neutralization
antibodies bind to viral surface proteins, preventing infection of a host cell
opsonization
antibodies bind to antigens on bacteria, triggering phagocytosis
positive feedback system of opsonization
- dendritic cells/macrophages present antigens on surface to become antigen-presenting cells
- stimulates humoral immunity
- opsonization enhances antigen presentation and humoral immunity
antigen-antibody complexes
may bind to complement protein, which triggers cascade of complement protein activation to form membrane attack complex
membrane attack complex
forms pore in the membrane of the foreign cells, leading to its lysis
how can humoral immunity kill infected cells
- viral infected cells often display part of virus on infected cell surface
- if antibodies specific for epitopes on these viral fragments, they bind to viral proteins
- natural killer cells induce infected cells to undergo apoptosis
agglutination
antibodies often have 2 receptor sites for antigens on pathogens, and binds to 2 antigens. this creates a clump, which is easier to engulf by macrophages
precipitation
binds to free-floating antigens and clumps them together, which are then engulfed by macrophage
how many different forms/classes of immunoglobulins can B cells express
5
different forms of immunoglobulins
- similar antigen-binding specificity
- different heavy chain C regions
- IgD is membrane bound
- IgA, IgE, IgG, and IgM are soluble
cytotoxic T cells
use toxic proteins to kill cells infected by viruses or other intracellular pathogens
what do cytotoxic T cells recognize
fragments of foreign proteins produced by infected cells
what does an activated cytotoxic T cell secrete
proteins that disrupt membranes of target cells and trigger apoptosis
CD8 protein function
between cytotoxic T cell and virus-infected cell, determines if infected cell needs to be killed or not
- helps recognize if class I MHC
what does cytokines interleukin 2 do
stimulates production of specialized helper T cells and cytotoxic T cells to eliminate threat
what tells the cytotoxic T cell to kill an infected cell
signal from helper T cell attached to macrophage
what is released in the gap between the cytotoxic T cell and infected cell
vesicles containing perforins
what do perforins do
create channels that allow water to rush into the cell
