Immuno1 0518FA Flashcards
lymph node functions
- nonspecific filtration by macros.
- store and activate B and T cells.
- Ab production.
LN follicle
site of B cell localization, proliferation.
located in outer cortex.
primary LN follicle
dense, dormant.
secondary LN follicle
pale central germinal centers, active
medullary cords
closely packed lymphocytes and plasma cells
medullary sinuses
contain reticular cells, macrophages
what part of lymph node communicates with efferent lymphatics?
medullary sinuses
paracortex
region between follicles and medulla.
high endothelial venules.
contains T cells.
where do T and B cells enter LN from blood?
postcapillary (high endothelial) venules
lymph drainage of upper limb, lateral breast
axillary LN
lymph drainage of stomach
celiac LN
lymph drainage of duodenum, jejunum
superior mesenteric LN
lymph drainage of sigmoid colon
colic to inferior mesenteric LN
lymph drainage of rectum (lower portion, above pectinate line)
internal iliac LN
lymph drainage of anal canal (below pectinate line)
superficial inguinal LN
lymph drainage of testes
superficial and deep plexuses to PARA-AORTIC LN
lymph drainage of scrotum
superficial inguinal LN
lymph drainage of thigh (superficial)
superficial inguinal LN
lymph drainage of lateral side of dorsum of foot
popliteal
right lymphatic duct drains…
right arm and right half of head
thoracic duct drains…
everything that right lymphatic duct does not
red pulp of spleen
SINUSOIDS: long vasc channels with fenestrated “barrel hoop” BM.
macrophages nearby.
white pulp of spleen
T cells in periarterial lymphatic sheath (PALS).
B cells in follicles.
what do splenic macros remove?
encapsulated bacteria
what happens with splenic dysfunction?
decrease IgM = decrease complement activation = decrease C3b opsonization =
INCREASED SUSCEPTIBILITY TO ENCAPSULATED ORGANISMS
encapsulated organisms
SHINS: Salmonella. H.influenzae. N.meningitidis. S.pneumoniae.
findings in postsplenectomy
- Howell-Jolly bodies: nuclear remnants.
- target cells.
- thrombocytosis.
thymus
site of T cell differentiation and maturation
thymus derived from…?
epith of 3rd branchial pouches
lymphocyte origin
mesenchyme
cortex of thymus
dense with immature T cells
medulla of thymus
pale with mature T cells and epith reticular cells.
contains Hassall’s corpuscles.
where does positive selection occur in thymus?
cortex
MHC restriction
where does negative selection occur in thymus?
medulla
nonreactive to self
innate immunity
receptors recognize GERMLINE encoded pathogens.
fast, nonspecific.
no memory.
cells in innate response
neutrophils. macrophages. dendritic cells. natural killer. complement.
adaptive immunity
receptors recognize pathogens that undergo VDJ recombination during lymphocyte development.
slow on first expo.
memory response is faster, more robust.
cells in adaptive immunity
T cells.
B cells.
circulating Ab.
MHC role
present Ag fragments to T cells.
bind TCR.
MHC I
encoded by HLA-A, B, C.
expressed on ALL NUCLEATED cells.
Ag loaded in RER with mostly intracellular peptides.
what cell does not express MHC I?
RBC (no nucleus)
MHC I mediates immunity against…?
viruses
what does MHC I pair with?
beta 2 microglobulin (aids in transport to cell surface)
MHC II
encoded by HLA-DR, DP, DQ.
expressed only on APCs.
Ag loaded following release of invariant chain in acidified endosome.
HLA-A3
hemochromatosis
HLA-B27
Psoriasis.
Ankylosing spondylitis.
IBD.
Reiter’s syndrome.
HLA-B8
Grave’s disease
HLA-DR2
Multiple sclerosis.
Hay fever.
SLE.
Goodpastures.
“2 Dr’s: Me and Hieu So Good”
HLA-DR3
diabetes mellitus type I
HLA-DR4
diabetes mellitus type I.
rheumatoid arthritis.
HLA-DR5
pernicious anemia (B12 def). Hashimoto thyroiditis.
HLA-DR7
steroid-responsive nephrotic syndrome
natural killer cells
use PERFORIN and GRANZYME to induce apoptosis in virally infected cells and tumor cells (NOT direct lysis)
which cytokines enhance NK action?
IL-12
IFN-a
IFN-b
IFN-g
NK cell surface markers
CD16 OR CD56
what induces NK cells to kill?
exposure to nonspecific activation signal on TARGET CELL or an absence of MHC I on target cell surface
which cell is the only lymphocyte member of innate imm system?
NK cells
B cell functions
- make Ab.
- type I hypersens: IgE.
- type II, III hypersens: IgG.
- hyperacute organ rejection.
T cell functions
- CD4+: help B cells make Ab. make IFN-g to activate macros.
- CD8+: kill virus-infected cells directly.
- type IV delayed hypersens: cell-mediated.
- acute and chronic organ rejection.
which Ab class is needed for opsonizing bact, neutralizing viruses?
IgG
which Ab class is needed for activating complement?
IgG, IgM
which Ab class is needed for sensitizing mast cells?
IgE
which Ab class is needed for type I hypersensitivity (allergy)?
IgE
which Ab class is needed for type II (cytotoxic) and type III (immune complex)?
IgG
positive selection
occurs in thymic cortex.
T cells expressing TCRs capable of binding self MHC molecules survive.
negative selection
occurs in thymic medulla.
T cells expressing TCRs with HIGH AFFINITY for self Ags undergo apoptosis.
what cytokine induces helper T cell transformation into Th1?
IL-12
what cytokine induces helper T cell transformation into Th2?
IL-4
antigen-presenting cells
- dendritic cells.
- macrophages.
- B cells.
which APC can activate naive T cells?
dendritic cells
Th1 cell function
- regulate cell-mediated response.
- secrete IL-2, IFN-g.
- activate macros and CD8+ T cells.
- inhibited by IL-10 (from Th2).
Th2 cell function
- regulate humoral response.
- secrete IL-4, IL-5, IL-10.
- help B cells make Ab.
- inhibited by INF-g (from Th1).
which Ab is produced more by B cells (aided by Th2)?
IgE > IgG
macrophage-lymphocyte interaction
activated lymphocytes secrete IFN-g.
macrophages release IL-1, TNF-a.
= stimulate each other.
cytotoxic CD8+ T cells
kill virus-infected, neoplastic, and donor graft cells by INDUCTING APOPTOSIS
cytotoxic granules of cytotoxic T cells contain…?
preformed proteins:
- perforin
- granzyme
- granulysin
perforin
helps deliver content of granules INTO target cell
granzyme
serine protease.
activates apoptosis inside target cell.
granulysin
antimicrobial.
induces apoptosis.
regulatory T cells
help maintain specific immune tolerance by SUPPRESSING CD4 and CD8 T cell effector functions.
surface markers of regulatory T cells
CD3, CD4, CD25
cytokines produced by regulatory T cells
ANTI-inflammatory:
IL-10 and TGF-b
what portion of Ab recognizes Ag?
variable part of L and H chains
what portion of Ab fixes complement?
Fc portion (IgG, IgM)
Fab portion
Ab-binding fragment. determines IDIOTYPE (Ag-specfic).
Fc portion
Constant.
Carboxy terminal.
Carbohydrate side chains.
Complement binding.
determines ISOTYPE (IgM, D, G, etc).
Ab functions
- opsonization.
- neutralization.
- complement activation.
Ab diversity
- random recombination of VJ (light chain) or VDJ (heavy chain) genes.
- random combination of heavy with light chains.
- somatic hypermutation - after Ag stimulation.
- addition of nucleotides to DNA during recombination (by terminal deoxynucleotidyl transferase)