Lymphocyte Migration

Meaning of homing

Leukocyte migration out of blood into tissue or injury site

Meaning of migration/recruitment

Movement of leukocyte through body

Meaning of recirculation

Homing of lymphocyte to secondary lymphoid organs, stay for a bit and then return to blood

Meaning of trafficking

Non random movement of cells

What causes inflammation

Neutrophil and monocyte migration to sites of injury/infection

What causes cell mediated immunity

Effector and memory T cell migration to site of injury/infection

Where do naive T and B cells migrate to

Secondary lymphoid organs

What is the function of selectin and selectin ligand

Mediate first step of low affinity binding of leukocyte to endothelial cell lining venules

What are selectin and selectin ligands

Plasma membrane carbohydrate binding adhesion molecule

What are the 3 types of selectin

P, E, L

P selectin responds to what

Histamine/thrombin

E selectin responds to what

IL-1 and TNF

L selectin expressed on what

Leukocyte

What is the function of integrin and integrin ligand

Mediate adhesion of cells to other cell or to ECM

What increase the expression of integrin

IL1, IL6 TNF alpha

What are the antigens associated with integrin

LFA-1 and VLA 4

What are the ligands of integrin

ICAM-1/VCAM-1 expressed on cytokine activated EC

Function of chemokine

Inflammation (recruitment of leukocyte), increased adhesion of leukocyte to EC, migration of leukocyte, traffic lymphocyte throughout secondary lymphoid organ, migration of DC from infection to lymph node

What are examples of chemoattractant

C3a, C5a, leukotriene

What is margination

Leukocyte that are heavier move away from the blood flow and closer to vessel lining

What is the process of selectin mediated rolling of leukocyte on endothelium

Cells that encounter microbe secrete cytokine → Selectin is expressed on EC → Blood vessel dilate and blood flow slows → Margination → Leukocytes pushed along EC in rolling motion

What increases affinity of integrin

Chemokine

How does leukocyte integrin disrupt junction protein

Binding of leukocyte integrin and ICAM-1/VCAM-1 causes phosphorylation by kinases on cadherin

What is the process of leukocyte movement through endothelium called

Diapedesis or paracellular transmigration

What do lymphocyte use to enter into lymph node

High endothelial venules

Where does lymphocyte exit the lymph node

Efferent lymphatic vessel

What stimulate T cell proliferation

IL2, IL12, IFN gamma

What do lymphocyte use to enter into blood vessel

Thoracic duct or cephalic lymphatic vein

What is the function of the CCR7 receptor

Facilitate naive T cell movement, DC migration

Fibroblast reticular cells in the T cell zone secrete what

cCL21/CCL19

What does CCL19/CCL21 do

Bind to CCR7 on T cell to facilitate specific movement

Where is there a high concentration of S1P

Blood and lymph

High concentration of S1P in blood causes what

Receptor to be internalized

What happens when a naive T cell is activated by an antigen

Suppression of S1PR for several days to prevent the cell from leaving the lymphoid organ

Why shouldn’t newly activated T cell leave lymphoid organs

Need to proliferate and differentiation into effector T cell in the lymphoid organ and not blood

Why can lymphocytes migrate to the spleen even if there is no HEV

Presence of CCR7 binding chemokines

What chemokine receptor is expressed on B cell

CXCR5

What is function of CXCR5

Promote movement in response of CXCL13 made by FDC