L5: lymphoid anatomy Flashcards
what are primary and secondary lymphoid tissues
primary = where BandT cells develop = thymus and bone marrow
secondary = where lymphocytes migrate to = lymph nodes, spleen, MALT
what do lymphoid vessels contain
lymph fluid
lymphocytes
tissue dendritic cells
what enters via afferent lymphatic
antigen loaded dendritic cells or macrophages
where do b cells proliferate in an infection
germinal centre of secondary follicle
where are t cells in the lymph node
paracortex
3 types of Mucosal associated lymphoid tissues (MALT)
gut (GALT)
Nasal (NALT)
bronchus (BALT)
what specific parts of body are MALT
tonsils
appendix
peyers patches in gut
what do mucosal cells allow
antigens to transit from gut lumen into lymphoid structures (peyers patches)
where does the spleen filter antigens from
blood via arteires (NO afferent lymphatics)
what is periarteriolar lymphoid sheaths (PALS)
portion of the white pulp of the spleen containing lots of T cells
surround the red pulp of the spleen
major lymphatic vessel that drains into blood
thoracic duct
what do high endothelial venules allow
the lymphocutes leave bloodstream and enter lymph node
what 2 main things direct lymphocyte migration
adhesion molecules
chemokines
where is the adhesion molecule L-selectin expressed and what is its ligand
all types of leukocytes
cd34
what is CR3 adhesion molecule expression on and what is its ligand
monocytes, neutrophils, macrophages
ICAM-1 ligand
what is PSGL-1 expressed on and what is its ligand
neutrophils
E and P selectin
4 steps of migration
rolling adhesion
tight binding
diapedesis
migration
how does rolling attachment work
inflammatory response to infection induce P-selectin and E-selectin expression on vessels
these recognise sulphated sialyl-Lewis X structures on immune cells
cells roll along the surface and slow down
how does firm attachment work
ICAM-1 and ICAM-2 are induced on vessels by TNF
this binds to LFA-1 and CR3 on leukocytes
forming firm attachment
what is extravasion
leukocytes crossing the endothelial wall
movement is known as diapedesis
CXCL8 and CCL2
chemokinesd produced at infection site
what is CXCL8 released by and what does it attract
macrophages
attracts neutrophils
