Immunology & Genetics Flashcards
two major mechanisms of the immune system
innate (natural) immunity and acquired (adaptive) immunity
innate (natural) immunity characteristics
present at birth, immediately responsive, non-specific
cells of the innate immune response
phagocytes: NK cells, neutrophils, macrophages/monocytes, and dendritic cells (note that these can also function as APCs in the adaptive response)
cells of the adaptive immune system
B & T lymphocytes, APCs (which can also act as phagocytes in the innate response)
two arms of the adaptive immune response
cellular (lymphocytes interacting with APCs) and humoral (antibody production)
adaptive immunity: naturally acquired active
developing immunity after exposure to a disease
adaptive immunity: naturally acquired passive
short term immunity from maternal antibodies passed to a fetus
adaptive immunity: artificially acquired active
developing immunity due to exposure to a vaccine
adaptive immunity: artificially acquired passive
short term immunization due to injection of antibodies
active vs passive adaptive immunity
active: an antigen is introduced and a specific antibody is formed, either natural from infection or induced from vaccination
passive: antibody is “given” to an individual (temporary, lasts as long as antibody remains active in circulation), either natural from maternal transfer of induced from injection
characteristics of lag and log phases of the primary (initial exposure) adaptive immune response
- lag phase (slow production of IgM antibody, can take days to weeks depending on antigenicity)
- log phase (steady production that plateaus and changes from IgM to IgG and then declines)
characteristics of the lag and log phases of the amnestic (repeat exposure) adaptive immune response
- lag phase (short rapid - hours to days - triggered by smaller amounts of antigen exposure to “primed” memory B cells
- log phase is increased/more drastic with a higher overall titer and longer plateau, primarily IgG produced
2 primary organs of the immune system & their function
where immune cells differentiate and mature
- bone marrow
- thymus (differentiation of T cells)
7 secondary organs of the immune system and their function
where immune cells interact with each other and antigens
- lymph nodes
- spleen
- liver
- tonsils
- adenoids
- appendix
- MALT (mucosa associated lymphoid tissue)
T helper cell functions and CD marker
CD3 (common) and CD4; recognize antigens presented by MHC class 2 receptors on APCs, produce cytokines, stimulate cytotoxic T cells, stimulate B cells to become plasma cells
T cytotoxic cell CD marker and functions
CD3 (common) and CD8; regulates immune response, interacts with MHC I receptors, destroys tumor cells and infected cells
B cells CD marker and functions
CD19, 20, 22; mature into plasma cells that produce antibodies or into memory B cells that participate in the amnestic immune response
hematopoietic stem cell CD marker
CD 33/34
type 1 hypersensitivity reaction: mediator, onset duration, and example
IgE mediated
within 1 hour
anaphylaxis
type 2 hypersensitivity mediator, onset, and example
IgG or IgM (cytotoxic)
hours to days
hemolytic anemia
type 3 hypersensitivity reaction mediator, onset, and example
immune complex mediated
1-3 weeks
lupus
type 4 hypersensitivity reactions mediator, onset, and example
T cell/cytokine mediated
days to weeks
Rash
interleukin broad definition
cytokine made by a WBC that acts on another WBC
IL-2 function
promotes proliferation of activated T and B cells, activates NK cells
factors affecting antigenicity
- size (>10,000 daltons)
- chemical compisition
- shape
- solubility
- foreignness to host
- route of exposure
- ability of host to mount an immune response
macromolecule composition of immunoglobulins
82-96% protein, 4-18% carb
variable region of immunoglobulin: location, function
amino terminal end (Fab region), antigen binding site
constant region of immunoglobulin: location and function
carboxy terminal/ Fc region. Location of heavy chain that determines class, binds complement
heavy and light chains of immunoglobulins are held together by
disulfide bonds (both within heavy chains and between heavy/light chains)
IgG
- % of total serum immunoglobulin
- structure
- functions
- subclasses
- half life
- binds complement?
- crosses placenta?
- 80% of total serum immunoglobulins
- monomeric structure
- responds after IgM as a part of the amnestic response, enhances phagocytosis, inactivates viruses & kills bacteria
- IgG1 (most abundant), IgG2, IgG3, IgG4
- 25 day half life (IgG1 and 2), 7-8 days for IgG3, 21-23 days for IgG4
- TWO IGG MOLECULES ARE REQUIRED TO BIND COMPLEMENT (CLASSICAL PATHWAY)
- All subclasses cross the placenta
IgM
- % of total serum immunoglobulin
- structure
- functions
- subclasses
- half life
- binds complement?
- crosses placenta?
- 5% of total serum immunoglobulins
- pentameric structure (has J chain, can be disrupted with 2ME or DTT)
- first Ig class produced by fetus, first Ig class produced in primary immune response, promotes lysis and phagocytosis
- IgM1 and IgM2
- 5-8 day half life
- BINDS COMPLEMENT - ONLY ONE MOLECULE REQUIRED
- does NOT cross placenta
IgA
- % of total serum immunoglobulin
- structure
- functions
- subclasses
- half life
- binds complement?
- crosses placenta?
- 15% of total serum immunoglobulin
- monomeric structure in serum, dimeric structure (with J chain) in secretions
- first line of defense in secretions, made by epithelium
- IgA1 and IgA2
- 5-8 day half life
- Activates ALTERNATIVE complement pathway
- Does NOT cross the placenta
IgD
- % of total serum immunoglobulin
- structure
- functions
- subclasses
- half life
- binds complement?
- crosses placenta?
- only trace amounts present in serum
- monomeric structure
- found of surface of unstimulated B cells, serves as receptor for antigens to start humoral differentiation
- no subclasses
- 2-3 day half life
- does not bind complement
- does not cross placenta
IgE
- % of total serum immunoglobulin
- structure
- functions
- subclasses
- half life
- binds complement?
- crosses placenta?
- trace amounts in serum
- monomeric structure
- sits of surface of basophils, triggers release of histamine
- no subclasses
- 2 day half life
- does not bind complement
- does not cross placenta
papain cleavage location
cleaves Fab region; leaves one Fc and two Fab segments
pepsin cleavage location
leaves 1 Fc segment and 1 Fab segment (both Fab regions still attached)
affinity vs avidity
affinity: strength of a single binding site
avidity: strength of the binding of the antibody overall
“the binding affinity is the strength of an interaction between two molecules, whereas avidity is the total strength of all non-covalent interactions between the two proteins”
direct vs indirect hemagglutination
direct: antibody can crosslink red cells (IgM)
indirect: red cell is sensitized/coated by an antibody (IgG) and requires anti-IgG to be visible to the naked eye
zeta potential
net negative charge on the surface of a red blood cell; antibodies must overcome this to directly agglutinate them (only IgM is capable of this)
macrophages in the spleen have receptors for which part of an immunoglobulin?
Fc; Fab portion would be bound to antigen
why do HLTA antibodies typically not cause red cell destruction?
low avidity; spleen macrophages can remove the coating immunoglobulin without actually destroying the red cell
2 factors that affect clinical significance of an antibody
- temperature of reactivity (37/body temperature = more significant)
- affinity/avidity towards red cell antigen (stronger = more significant)
2 main outcomes/goals of complement cascades
- opsonization
2. MAC formation
autosomal dominant inheritance pattern
not affected by sex; appears in every generation; affected individuals transmit to half of their offspring, unaffected individuals do not transmit
autosomal recessive inheritance pattern
not affected by sex; trait appears only in ~1/4th of siblings (does not appear in parents or their offspring)
sex-linked dominant inheritance pattern
affected males will transmit to all daughters but not to sons
affected females will transmit to half of their children (either sex); however, monozygous females will transmit to all of their children
sex-linked recessive inheritance pattern
affected males will transmit to all daughters but only half of sons
hardy-weinberg equations
- p^2 + 2pq + q^2 = 1, referring to GENOTYPE frequencies
2. p + q = 1, referring to GENE frequencies
