SECRETS Immuno - Basics Flashcards
primary lymphoid organs
bone marrow = B & T
thymus = T
fetal liver
where lymphocytes mature
secondary lymphoid organs
appendix
tonsils
peyer’s patches
mature lymphocytes respond to antigens on APCs
innate immunity
first line of defense
nonspecific
PRRs –> recognize PAMPs
prevent microbes from entering
destroy/limit growth
neutrophils, macrophages, eosinophils, basophils, mast cells, NK cells
adaptive immunity
B, plasma cells
helper T, cytotoxic T cells
specific, memory
bridge from innate – adaptive
dendritic cells
cell mediate immunity
helper t Cells
vs virus, fungi, mycobacteria
type IV hypersensitivity, tumor destruction, graft rejection
MHC class I
all nucleated cells
interact with CD8+ T cells –> destruction
display nonself peptides that have been processed intracellularly
MHC class II
APCs = dendritic cells, macrophages, memory b cells
interact with CD4+ T cells –> upregulate Th cytokine production –> macrophage activation, plasma cell proliferation
display exogenous nonself peptides obtained via phatocytosis, endocytosis
ADCC
bing IgG to Fcy receptors
destruction via phagocytes or NK cells
IgA
mucosal immunity
poor activator of complement
IgD
on mature B cells
unclear role
IgE
on tissue mast cells and blood basophils
mediate type I hypersensitivity
parasitic killing via ADCC
IgG
in blood, crosses placenta longest half life ligand for Fc receptors activate classical complement pathway most abundant Ig in secondary immune response highest affinity (strength)
IgM
in blood, pentamers
activate classical complement pathway
earliest Ab produced
most abundant Ig in primary immune response
highest avidity (number of binding sites)
neutrophil chemotaxis
IL-8
C5a
LTB4
C1 esterase inhibitor deficiency
overproduce anaphylatoxins –> recurrent angioedema
contraindication for ACEi
C2 or C4 deficiency
resemble autoimmune disease, usually asx
C2 is most common deficiency, assoc with septicemia (strep pneumo)
C3 deficiency
reduced opsonization –> recurrent pyogenic infections
type III hypersensitivity = decreased immune complex clearance
C5-8 deficiency
no MAC
increased risk of neisseria infections
MAC can kill most unenapsulated gram neg organisms
DAF deficiency
increased complement mediated hemolysis
paroxysmal nocturnal hemoglobulinuria
macrophage
CD14+CD16+
CD40+
phagocytosis
APC to T cells
secrete IL-1, IL-6, IL-8, IL-12, TNF-a
eosinophil
phagocytic
parasitic organisms
extremely basic proteins in granules
basophil
nonphagocytic
allergic response
release histamine, IgE on surface
mast cell
allergic response, similar to basophil
release histamine, FcE on surface
helper T cell
CD4+
activated by foreign antigen on MHC II
regulate fxn of other immune cells
TH1
induced by IL-12
secrete IFN-y –> activate macrophages & TH1, suppress TH2, kill intracellular pathogens
IL-2 –> activate CTLs & propagate response, T cell proliferation
TH2
induced by IL-4
secrete IL-4 --> promote IgE & IgG class switch & B cells to plasma cells IL-5 --> promote eosinophil prolif, aid IgA class switch IL-10 --> anti-inflammatory
cytotoxic T cell
CD8+
direct cell killing
MHC I
perforins, granzymes, IFN-y, TNF-B, FasL
B cell
CD19+CD20+
diff into plasma cells
release antibodies
APC for Th cells (MHC II)
NK cells
CD16+
large granular lymphocyte
lyse virally infected cells (ADCC) and tumor cells with less MHC I
perforins, granzymes, IFN-y, TNF-a
secreted by T cells
IL-3
hematopoietic stem cell diff into myeloid progenitors
macrophage cytokines
TNF-a = acute phase, responsible for septic shock and cachexia IL-1 = acute phase, fever IL-6 = acute phase, fever IL-8 = neutrophil chemotaxis IL-12 = TH1 cell diff, NK activation
