Short note on Chemokines.

Chemokines are a family of small proteins that act primarily as chemoattractants for specific types of leukocytes.
They are classified into four major groups according to the arrangement of cysteine (C) residues in the proteins.

1. C-X-C Chemokines - have one amino acid residue separating the first two of the four conserved cysteine residues.
2. C-C Chemokines - has first two conserved cysteine residues adjacent.
3. C Chemokines - lack the first and third of the four conserved cysteines.
4. CX3C Chemokines - Contain three amino acids between the two cysteines.

Chemokines have two main functions:

1. In acute inflammation - Chemokines stimulate leukocyte attachment to endothelium and they stimulate migration of leukocytes in tissues to the site of infection or tissue damage.
2. Maintanance of tissue architecture - Some chemokines are produced constitutively in tissues and are sometimes called homeostatic chemokines.