[Fractalkine--structure, functions and biological activity]

Although chemokines, as chemotactic factors, were already known in 70's of the past century, it was only the progress in molecular biology, genetics and immunology which occurred in the past few years that opened the way to discover new molecules, their chemical structure and biological functions. Fkn (fractalkine, CX3CL1) is a unique chemokine and the only representative of CX3C group. It exists as a membrane-bound and soluble form. It interacts with cells expressing CX3CR1, a G-coupled protein receptor. The polymorphism of CX3CR1 gene modulates Fkn affinity to its receptror, which influences the risk of development and progression of various diseases. Its unique character is determined by its functions. Fkn is not only a chemotactic factor, but it also participates in leukocyte trafficking, adhesion and cytotoxic activities, modulates expression of cytokines, adhesion molecules, free oxygen radicals, iNOS and influences apoptosis. Its elucidation should not only help understanding of molecular events occurring in many autoimmune inflammatory, neoplasmatic diseases, but would allow to use Fkn, its receptor, or anti-Fkn antibodies in treatment of those diseases.