final Flashcards
active immunity
body is exposed to pathogen and produces its own antibodies (natural: infection, artificial: vaccination)
passive immunity
occurs when we acquire antibodies made my another organism
natural: placenta, breast milk, artificial: gamma globulins, faster and does not generate memory
constant region
on the main tail - determines the mechanism used to destroy the antigen, structural framework, same on the antibody
Fab
the light chain on the tails - the binding fragment - recognizes the antigen, consists of two variable and two constant domains
Fc
he main tail, crystallizable fragment - interacts with other elements of the immune system such as phagocytes or components of the complement pathway to promote removal of the antigen
variable region
on the two tails, antigen specificity of the antibody, binds to the antigen, divalent
IgM
pentamer, associated with primary response, strongly activates the complements, naive B cells, micro heavy chain
IgG
monomer, most abundant isotype in the serum, longest half life (23 days), 4 subclasses (IgG1-4), most IgG cross the placenta (FcRB), opsonin (Fc receptor fetus to placenta), activates complements gamma heavy chain
IgA
mono to tetramer, in external excretions (saliva, intestinal and bronchial mucus, breast milk) alpha chain
IgE
monomer, target parasites and allergen, decorate mast cells, basophils, and eosinophils through FcR, causing degranulation, transportation relies on the Fc fragment
IgD
appear on the surface of B cells, the role is unclear
five physiological functions of antibodies
- antigen clumping (valence) and neutralization
- opsonization
- ADCC
- complement fixation
antigen clumping and neutralization
toxins, control infection, targets of the therapeutic antibodies
opsonization
neutrophils and macrophages *FCgama, IGg - opsonin an antibody or other substance which binds to foreign microorganisms or cells making them more susceptible to phagocytosis.
ADCC
through degranulation of mast cells, basophils, eosinophils and NK (IgE, IgG) - antibody-dependent cell-mediated cytotoxicity, is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies.
complement fixation
C3b (potent in opsonization: tagging pathogens, immune complexes (antigen-antibody), and apoptotic cells for phagocytosis) opsonization, degranulation, chemotaxis, MAC (membrane attack complex) (IgM, IgG) - the process of binding serum complement to the product formed by the union of an antibody and the antigen for which it is specific that occurs when complement is added to a suitable mixture of such an antibody and antigen
primary immune response
clonal selection - plasma membrane of naive B cells, IgA, IgB heterodimer to form BCR, BCR binds to specific antigen leading to receptor oligomerization, specific clone of the B cells proliferates, specific clone of the B cell proliferates and differentiates into IgM secreting plasma membranes and memory B cells, activated B cells can undergo isotope switching and differentiate into plasma cells (IgG, Iga, IgE corresponding memory B cells
secondary response
memory cells encounter the same antigen, rapid clonal expansion to effector to effector cells, differentiation into isotope plasma cells, antibody production and secretion, secondary response is faster and stronger
MHC class I
expressed on all nuceated human cells and recognized by cytotoxic t cells - CD8 binding- B2 microglobulin, cytotoxic T cell attack the virus-infected cells
MHC class II
expressed on all antigen-presenting cells (macrophages, B cells, dendritic cells) recognized by helper T cells - CD4 binding, attacks the antigen presenting cells
cTcells attack cells expressing antigen through MHC-I
release pore-forming perforins, release granzymes that activate apoptotic cascade, activate d
helper tcells enhance immunity
secrete cytokines that activate other immune cells (IFNgamma (TH1) interleukins (activation of B cells, mast cells and eosinophils: TH2 activation of cytotoxic T cells (TH1) 2. bind to B cells and promote their differentiation into plasma cells and memory B cells (including class switching) - HIV destroys helper T cells
integrated immune response to bacterial infection
inflammation, components of bacterial cell wall can directly activate complement cascade leading to chemotaxis, opsonization and MAC formation, alert adaptive immune response: antibody-mediated if bacteria are extracellular, activation of helper T cells lead to cytokine secretion and increased b cell clonal expansion antibody production and B and helper T memory cell generation, repair
integrated immune response
humoral and cell mediated, innate and antibody mediated defense (cestracellular - body cells are infectd cytotoxic T cells and NK cells activated macrohages also secrete cytokines (IFN), NK cells recognize some infected cells lacking MHC-I and kill them -