Immunology Flashcards
lymph node follicles
site of B cell localization and proliferation
- primary are dense and dormant
- secondary have active pale center
lymph node medulla
cords and sinuses - sinuses communicate with efferent lymphatics and contain reticular cells and macrophages
paracortex of lymph nodes
houses T cells, between follicles and medulla, contains HEVs where lymphocytes enter
region of lymph node not well developed in DiGeorge syndrome
paracortex
final lymph drainage
right lymphatic duct to right side above diaphragm, everything else to thoracic duct
superficial inguinal drainage
think skin - anal canal, below ubilicus, scrotum, vulva
para-aortic drainage
testes, ovaries, kidneys, uterus
celiac drainage
liver, stomach, spleen, pancreas, upper duodenum
composition of white pump in spleen
follicle has B cells, periarteriolar lymphoid sheath has T cells
marginal zone in spleen
between red and white pulp - contains macrophages and special B cells, where APC capture antigens for recognition by lymphocytes
people are susceptible to what after spleenectomy
encapsulated organisms (pneumococcal, Hib, meningococcal)
things seen in spleenectomy
- Howell-Jolly bodies (nuclear remnants
- target cells
- thrombocytosis (loss of sequestration)
- lymphocytosis (loss of sequestration)
THymus is derived from…..
THird pharyngeal pouch
Hassall corpuscles
epithelial reticular cells in thymus
thymoma is associated with….
myasthenia gravis and superior vena cava syndrome
MHC Class 1
- bind to TCR and CD8
- 1 long chain and 1 short chain (alpha 1-3 and beta2 microglobulin)
- expressed on all nucleated cells
- present endogenous peptides
MHC class 1 loading
rough endoplasmic reticulum after delivery via transporter associated with antigen processing
MHC class 2
- bind to TCR and CD4
- 2 equal chain
- present on all APCs
- exogenous protein presented to CD4 cells
- loaded from acidified endosome
MHC
present on cells, binds to T cell receptor
HLA A3
hemochromatosis
HLA B8
Addison disease, myasthenia gravis, Graves
HLA B27
seronegative arthopathies
HLA DQ2/DQ8
celiac disease
HLA DR2
MS, hay fever, SLE, goodpasture
HLA DR3
diabetes type 1, SLE Graves, Hashimoto, Addisons
HLA DR4
Rheumatoid arthritis, type 1 diabetes, Addison
HLA DR5
pernicious anemia and B12 deficiency and Hashimotos
NK cells
innate immunity
- perforin and granzymes to induce apoptosis of virally infected cells and tumor cells
positive and negative selection in thymus
positive - in cortex, TCR that bind to self MHC survive
negative - in medulla, TCR with high affinity for self antigen die
autoimmune regulator (AIRE)
allows self-antigen presentation in thymus, deficiency leads to autoimmune polyendocrine syndrome-1
TH1 activators
IL12 IFN-gamma
TH2 activators
IL2, IL4
TH17 activators
TGF beta, IL6
TH1 cells
- secrete gamma IFN, IL2
- activates macrophages and CTLs
- inhibited by IL-4 and IL-10
TH2 cells
- Secretes IL4,5,6,10,13
- recruits eos for parsite defence and promotes IgE by B cells
- inhibited by gamma-IFN
IL-12
released by dendritic cells, macrophages and APCs to make TH1 cells
IFN-gamma
macrophage stimulation
expression in Tregs
CD3, CD4, CD25, FOXP3
anti-inflammatory cytokines
IL-10 and TGF-beta
IPEX (immune dysregulation, polyendocrinopathy, enteropathy, Xlinked syndrome)
defect in FOXP3 (no Treg) leading to autoimmunity - associated with diabetes in male infants
CD 28 and B7
B7 on APC and CD 28 on T cell, leading to activation
CD40 and CD40L
secondary signal in B cell activation, CD40 on B cell, CD40L on T cell
4 Cs of Fc
- constant
- carboxy terminal
- complement binding
- carbohydrate side chains
mechanisms for antibody diversity
- random recombination of VJ and VDJ
- random nucleotide addition by terminal deoxynecleotidyl tranferase
- random light and heavy
mechanisms for antibody specificity
somatic hypermutation and isotype switching
antibodies that fix complement
IgG and IgM
antibody that crosses placenta
IgG
CRP
acute phase reactant - opsonin, fixes complement, facilitates phagocytosis
marker of inflammation
ferritin
acute phase reactant - sequesters iron
fibrinogen
acute phase reactant - coag factor promoting endothelial repair
hepcidin
acute phase reactant - decreased iron absorption and decreased iron release from macrophages leading to anemia of chronic disease
serum amyloid A
acute phase reactant - long elevation can lead to amyloidosis
classic pathway activation
IgG and IgM (GM makes classic cars)
alternative pathway activation
microbe surface molecules
lectin pathway activation
mannose or other sugars on microbe surface
complement opsonin
C3b (b binds bacteria)
anaphylatoxins complement
C3a, C4a, C5a
neutrophil chemotaxis complement
C5a
complement inhibitors
C1 esterase and DAF (CD55)
C3 deficiency
increase in respiratory tract infections, more type 3 reactions
C5-C9 deficiency
Neisseria bacteria
C1 esterase inhibitor deficiency
hereditary angioedema due to activation of kallikrein, increase bradykinin - low C4
