Lymphocyte recirculation Cell adhesion molecules Chemokines Extravasation Lymphocyte trafficking a. Naive lymphocyte recirculation b. Effector and memory cell trafficking

1. LeukocyteTrafficking

2. Index
Lymphocyte recirculation
Cell adhesion molecules
Chemokines
Extravasation
Lymphocyte trafficking
a. Naive lymphocyte recirculation
b. Effector and memory cell trafficking

3. Lymphocyte re-circulation
Lymphocytes
constantly re-circulate
from blood to spleen,
lymph nodes, and 3°
lymphoid tissues
Continual circulation
allows max. no. of
lymphocytes to
encounter Ag.
A complete circuit can
be performed 1-2 per
day.

4. Cell Adhesion Molecules(CAMs)
Endothelial cells exhibit ‘cell adhesion
molecules’ – CAMs
Recirculating leucocytes form receptors which
bind to CAMs

5. Types of CAM’s
Selectins – resp. for initial
contact between leukocytes
and endothelial cells
• Bind to specific CHO
groups (i.e., mucins)
• Types-L-,P-,E-selectins
Mucins – glycosylated
proteins
Bind to selectins on
endothelium
Eg, L-selectin recognizes
mucins (CD34 and glyCAM)
on endothelium of lymph
nodes

6. Integrins – heterodimer
proteins
• Expressed by leukocytes
• Bind to ICAM on vasc.
endothelium
ICAM’s – CAM’s with Ig
domains
• expressed on vasc.
Endothelia
• Bind to integrin.

7. Chemokines
• Small polypeptides of 90-130 a.a.
• Are major regu7lator of leukocyte trafficking.
• Types of chemokines-
1. C-C subgroup
2. C-X-C subgroup
• Types of chemokine receptors-l
1. CC receptors
2. CXC receptors

9. Extravasation
Blood flow
Neutrophil

10. Rolling Activation Adhesion

11. Lymphocyte trafficking
Defn-Process of migration of different lymphocytes into
different tissues.
High-endothelial venules(HEV’s)
• Are cuboidal cells +nt in capillaries.
• Express a variety of CAMs.
• CAMs that are tissue specific-Vascular addressins.

12. Naïve T cell Recirculation

13. Effector cell and memory cell
recirculation