excellent review article : ley et al., nature immunology reviews, 7:678, 2007
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Excellent review article : Ley et al., Nature Immunology Reviews, 7:678, 2007Video Acknowledgments to Dr. Tim Springer, Harvard University
Homing of naïve/effector/memory cells
Recruitment of phagocytic cells
Leukocyte/Lymphocyte Trafficking
Functions in Immune Response:
Adhesion Molecules
Leukocyte Recirculation
IMMUNOSURVEILLANCE
Critical for Effective Immune Responses
Constant Process – required for rapidly controlling infections
Leukocyte adhesion deficiencies – highlight the role of certain adhesion molecules in this process
The Big PictureEndothelial Cells
Blood Flow -->
PMN
Rolling Activation
Firm Adhesion
Diapedesis
ADHESION MOLECULE FAMILIES(and related proteins)
1.
2.
3.
4.
Selectins - Family of C-type Lectins
Integrins - Family of HeterodimericReceptors b2-integrins
Cell Adhesion Molecules (CAMs) - Composed of Ig Domains
Signaling Molecules (Receptors/Ligands) - Chemoattractant and Chemokine Receptors
Physical Factors InfluencingLymphocyte/Leukocyte Migration
1.
2.
3.
Blood Flow
Physical Barriers
Ability to Detect Infection
Step 1: Rolling
Selectins & CHO LigandsStep 1: Rolling
***
Endothelium
Leukocyte
P-Selectin
E-Selectin
L-Selectin
Sialyl Lewis X and others
Intravital Microscopy. The mouse mesentery preparation.
The following in vivo microscopy is of postcapillary venules from a different type of preparation, hamster cheek pouch
Timothy A. Springer, Harvard Medical School
Timothy A. Springer, Harvard Medical School
IMMUNOSURVEILLANCE
Incomplete glycosylation of sLewx: no binding to selectins LAD II - Leukocyte Adhesion Deficiency Type 2
Step 2: Activation
Chemotactic Receptors & Ligands
Step 2: Activation
FMLP
IL-1
C5aTNF-a
Infection
1. Activates both cell types – endothelial and leukocyte2. Causes “inside-out signaling3. Gradient-dependent migration of leukocytes
b2-integrins and Inflammatory Activators
NH2
COOH
FMLPPAF
IL-8
C5a
a bG protein Complex
Inside-Out Signaling
Cell AdhesionMolecules - CAMS
Endothelium
S S S SS SS SS SS SS S
S S S SS SS SS SS S
S S S SS SS SS SS SICAM-1
ICAM-2
VCAM
PECAM
Step 3: Firm Adhesion
Infection Inflammatory Mediators
InflammatoryMediators
LAD I - Leukocyte Adhesion Deficiency Type 1Missing functional CD18 : no expression of CD11a-d
PECAM:PECAM Integrin:ICAM
JAM-1:Integrin JAM-1:JAM-1
Step 4: Diapedesis
Endothelial Cells
Blood Flow
Leukocyte
Rolling
Selectin-mediated
1 Activation
Cytokine-mediated
2
FirmAdhesion
Migration
Integrin-mediated
34
Naïve Lymphocyte Homing in Lymph Nodes
L-Selectin
SSSSSSSSSS
LFA-1
ICAM-1PNAd
CCR7
CCL19
Rolling
Activation Firm Adhesion
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