The rapidly expanding superfamily of chemokines (chemo tactic cytokines) are important mediators of white blood cell trafficking and activation. Chemokines are small proteins (60 -70 amino acids) containing conserved cysteine residues which form disulphide bonds.
Most of the chemokines described to date contain four conserved cysteine residues and two subgroups have been delineated depending upon the organisation of the first two cysteine residues in the protein.
C-x-C chemokines which include Interleukin 8 (IL-8) and epithelial derived neutrophil attractant-78 (ENA-78) are potent chemoattractants for neutrophils but not monocytes.
Chemokines of the C-C subfamily such as RANTES and Monocyte Chemoattractant Protein 1 (MCP-1) are potent chemoattractants for monocytes but not neutrophils.
Some chemokines of the C-C subfamily can also mediate chemotaxis and activation of T- lymphocytes and basophils.
Of the currently identified
C-C chemokines, RANTES, MCP-3 and eotaxin are potent in eosinophil
and monocyte chemoattraction and activation assays at nanomolar
concentrations.