secondary lymphoid organs

antigens

lymphocytes encounter _______ in secondary lymphoid tissues

marginal sinus

separates read and white pulp

B, t, Ag

these cells enter the spleen through the marginal sinus

macs and dcs

capture Ag in mariginal zone

marginal zone b cells

respond first in marginal zone of spleen

HEVs

b and t enter the lymph nodes through

DC and Ag

enter the lymph nodes through afferent lymphatics

peyer's patch

part of MALT

M cells

ag enters the peyer's patch through the

vasculature

here b and t cells enter the peyer's patch

neutrophil entry

lymphocyte entry into lymph node follows same path as

CCl19 and CCl21

bound by HEV on surface, attract lymphocytes to form tight adhesion

selectins

guide luekocytes to particular tissues

l selectin

cd26l, critical for lymphocyte entry into secondary lymphoid tissues which binds to sugar groups on HEVs for tight adhesion

rolling

interactions between l selectin and sugar groups permit weak

LFA-1

promotes t cell adhesion and interaction with targets

CCR7

signaling promotes conformational change to high affinity LFA-1 and FLA-cluster

FRCs

in t cell zone, facilitate interactoins of t cells and dcs

conduits

made by FRCs, network through t cell zone, presents CCl19 and CCL21

CCR7

attracts DCs and T cells to FRCs, causes migration

afferent lymphatics

free antigens enter FRC through ______________, allowing it to be presented to DCs

CXCL13

FDCs in follicles make _________- to attract B cells to FRCs

Ag in lymph nodes

naive t cells become activated by DCs displaying

cortical sinuses

if t cells are not activated, they drain back to the lymph nodes through

self peptide:MHC complexes and IL-7

while LN, non activated t cells receive signals through _____________ to stay alive and proliferate

clonal expansion of t cells with identical antigen specifity

when a t cell recognizes Ag presented by dendritic cell, it arrests migration and begins to proliferate in LN

effector function

once t cell has proliferated for a feew days, it aquires _____ and can leave LN

egress

________ from LN also follows a chemical gradient via GPCR signalging

S1P

used to draw out T cells from the lymph node if they do not meet an antigen, high concentration in lymph and blood

low

concentration of S1P in LN

S1PR1

promotes egress of t cells,

S1P lyase

degrades S1P, keeps concentration low in LN

expresses B7 molecules and adhesion

when DC is activated by pathogen it

MHC II

B7 and adhesion molecues on activated DCs attract _____ to activate t cells

naive t cells

DCs specialized in activating

ag to t cells

b cells in follicles are activated by presenting

conventional DCs

activate naive t cells

plasmacytoid DCs

responde to viral infections be secreting large amounts of type one IFNs

PRRs

when DCs ecnounter pathogens ____ are triggered

DEC205

enables pathogen phagocytosis of DCs

enable interactions

DCs in LN upregulate molecules to __________ with naive t cells

paracortex

in LN, mature DCs interact with t cells in the

stable

after activation of the DC, the MHCII molecules because _____ on surface and overlap less with lysosomes

no longer

maturation induces stabilization of MHC II and costimulatory molecules and DCs in LN are _________ phagocytic

prime t cells or transfer Ag

DCs migrating to LN can