Detection of fractalkine in human seminal plasma and its role in infertile patients.

Abstract

Fractalkine is a relatively newly discovered CX(3)C chemokine, which is a chemoattractant for T cells, monocytes and natural killer cells. Several reports have demonstrated the association between chemokine levels in seminal plasma and semen quality. The fractalkine levels in ejaculates from normal donors and infertile male patients with or without asthenozoospermia, were examined and correlated with sperm motility and morphology. Western blot analysis showed fractalkine protein to be present in the seminal plasma. Fractalkine titres in the seminal plasma of infertile men with asthenozoospermia (0.64 +/- 0.04 microg/ml; n = 58) were lower than those in patients without asthenozoospermia (0.94 +/- 0.10 microg/ml; n = 22, P < 0.01) and fertile donors (1.04 +/- 0.07 microg/ml; n = 10, P < 0.001). There was no significant difference between fractalkine levels in patients with and without leukospermia. No significant correlation was found between fractalkine and interleukin-8 levels in seminal plasma. Sperm motility was positively correlated (R(2) = 0.14, P < 0.001) with fractalkine concentration. The existence of CX(3)CR-positive leukocytes in semen was confirmed using specific primers for CX(3)CR. These results suggest that fractalkine is a chemokine associated with sperm motility and the migration of CX(3)CR-positive leukocytes into semen.