Seminal plasma lactoferrin but not transferrin reflects gonadal function in dogs

Lactoferrin purified from canine seminal plasma by a three-step chromatography procedure had a molecular mass of 75.2 kDa and cross-reacted with antiserum to equine seminal plasma lactoferrin. Seminal plasma lactoferrin concentrations were determined by a competitive enzyme-linked immunosorbent assay (ELISA) by using rabbit anti-equine lactoferrin antibody and alkaline phosphatase-labeled goat anti-rabbit IgG antibody in 14 normal dogs and found to range from 12 to 197 mug/ml, with a mean value of 77 +/- 59 mug/ml (the mean +/- SD). Seminal plasma transferrin concentrations were determined by a sandwich ELISA with goat antibody to canine serum transferrin and alkaline phosphatase-conjugated goat anti-canine transferrin antibody and found to range from 0.32 to 12.6 mug/m/, with a mean value of 2.44 +/- 3.25 mug/ml. The lactoferrin concentration significantly correlated with the sperm concentration (r=0.7025, P<0.01), but there was no significant correlation between the seminal plasma transferrin concentration and sperm density. These results indicate that seminal plasma lactoferrin, but not transferrin, reflects gonadal function.