Biomedical Engineering Reference
In-Depth Information
10
CHAPTER
Adhesion Molecules in Leukocytes and
Their Reactivity
Maria Bokarewa and Piotr Mydel
Department of Rheumatology and Infl ammation Research,
University of Göteborg, 41346 Sweden
ABSTRACT
Adhesion molecules belong to central regulators of leukocyte functions mediating
cell-cell and cell-matrix interactions. In leukocytes, adhesion molecules mediate
canonical functions participating in surface binding, transendothelial and
interstitial migration. Additionally, each leukocyte type constitutively expresses
or gains the expression of adhesion molecules characteristic for its functions.
h e ef ect on cell function depends on the type of adhesion molecule involved,
the receptor partner it mobilizes, and the pathway of intracellular transduction it
activates. Neutrophils and eosinophils have a limited panel of adhesion molecules
which helps their rapid mobilization to the site of infectious or allergenic entrance,
phagocytosis and degranulation. In monocytes, adhesion molecules facilitate
phagocytosis and interstitial migration and support the broad dif erentiation
capacity forming the subset of macrophages required in a particular tissue
environment. Adhesion molecules on lymphocytes are key regulators of T and
B cell maturation, tissue-specii c trai cking and antigen presentation. h e major
groups of adhesion molecules identii ed in leukocytes include selectins together
with their ligands mucins, and integrins with their specii c ligands. Ligation of
integrins by their counterparts or by the proteins of extracellular matrix containing
RGD-motif induces conformation changes and clustering of integrins in cell
membrane followed by intracellular signals (outside-in signaling). Stimulation
of leukocytes through growth factor receptors, G-protein coupled receptors, and
immunoreceptors potentiates the ai nity of adhesion molecules and their reactivity
(inside-out signaling). A net of intracellular signaling initiated by these receptors
