Chemokines

Chemokines = chemotactic cytokines constituting a superfamily of soluble molecules:

• of small protein nature (8 to 12 kDa)
• secreted by a wide variety of cells
• exerting chemotaxis on leukocytes
• involved in the development, differentiation, anatomical distribution, circulation and effector functions of these cells.

Structure

small proteins: 8 to 12 kDa – 66 to 78 aa
soluble form → fixation on the glycosaminoglycan of the cell surface

Preserved aa sequence patterns.

Except: Fractalkine and CXCL16 which have a membrane expression.

Type of chemokines

• CC (chemokines α)
• CXC (chemokines β)
• the C chemokine
• the CX3C.

function of Chemokine

Homeostatic chemokines: directly involved in the homeostasis and homing of lymphocytes and their circulation

Inflammatory chemokines: helping cell recruitment at the site of inflammation.

Dual-function chemokines.

Chemokine Receptors

19 functional receptors listed, expressed mainly on leukocytes and divided into 04 families
each family of receptors interacts specifically with a given family of chemokines:
• CCRs linking CC chemokines: 11 receptors (CCR1 to CCR11)
• CXCRs binding CXC chemokines: 5 receptors (CXCR1 to CXCR5)
• CX3CR binding the CX3C chemokines: 1 single receptor (CX3CR1)
• XCRs linking XC chemokines: 1 single receptor (XCR1)