Lecture 14 Flashcards
Innate immunity
First line of defense, resistance to microbe or foreign material, NO MEMORY (skin, mucus)
Adaptive immune response
activated by cells and chemicals of innate immunity, tailored to particular foreign agent, MEMORY
Characteristics of adaptive immunity (4)
- discrimination between self and non-self
- specificity
- Diversity
- memory
Naturally acquired active immunity
specific immunity a host develops after exposure to foreign substance
Naturally acquired passive immunity
Transfer of antibodies (mother to infant - breast milk)
artificially acquired active immunity (vaccine)
intentional exposure to foreign material (antigen)
Artificially acquired passive immunity
preformed antibodies or lymphocytes produced by one host are introduced into another host
Antigens
self and non-self substances that illicit an immune response, large complex molecules
Antigenic determinant sites (epitopes)
site on antigen that is recognized by specific antibody, valence = # of epitopes on antigen
T cell development
multiple subsets of t cells, initiate, orchestrate, an adaptive immune response, originate from CLP cells from bone marrow
Thymic selection
Determines what kind of T cell any given immature cell will become
Pos - Sorted into 2 types based on t cell receptor
neg - t cells that recognize self antigen destroyed
T helper cells
CD4+ cells, activated by antigen presentation, role is to help other immune cells by releasing signals
Different T helper cells (most important)
TH0 (mature, not activated), TH1 (help activate macrophages), TH2 (help B cells produce antibodies), TH17 (assist in antibacterial responses), Treg (control lymphocyte responses)
Cytotoxic t cells (2 types of cell they can kill)
CD8+ cells activated by antigen presented by dendritic cells
1. virus infected
2. cancer neoantigens
Kills by perforin which activates apoptosis
B cells
mature in bone marrow, has to be activated by specific antigen
B cell receptors
made of membrane bound antibodies, major naive b cells attach an antibody to their cell membrane antibody faces antigen
T dependent antigen activation (require 2 signal), (what they differentiate to)
1.antigen b cell receptor specific interaction
2. Activated t helper binds b cell presented antigen and secretes b cell growth factors
1. Plasma cell 2. Memory cell
antibody (found where, what does it recognize)
found in blood serum, tissue fluids, mucosal surfaces, antibody can recognize and bind antigen that caused its production
Antibody (made out of)
immunoglobulin, glycoprotein made by activated b cells, serves as antigen receptor on b cell surface
Antibody (chains)
Fc (crystallizable fragment), 2 Fab (antigen binding fragment), light chain
Antibody structure (and regions)
four polypeptide chains (2 heavy, 2 light), connected by disulfide bridges
1. constant regions - does not vary
2. variable regions - sequence varies
Immunoglobulin function (Fab)
binds antigen specifically, marks antigen for immunological attach, activates non specific defence mechanisms that destroy antigen
Immunoglobulin function (Fc)
mediates binding to host tissue, receptor on various immune cells, first component of complement system
Primary antibody response
relatively slow antibody response when antigen is encountered for first time
Secondary antibody response
occurs upon subsequent exposure to same antigen, rapid, prevents illness, MEMORY
Consequences of antigen-antibody binding
toxin neutralization (prevent toxic action), precipitation + agglutination (aids phagocytosis), opsonization (foreign microbe coated with antibodies cells destroyed)
