Boar seminal plasma or hen's egg yolk decrease the in-vitro chemotactic and phagocytotic activities of neutrophils when co-incubated with boar or bull sperm

The objective was to determine the effects of boar seminal plasma and hen's egg yolk on chemotaxis and phagocytosis of porcine and bovine polymorphonuclear neutrophils (PMNs) in vitro. Chemotactic activity of PMNs was determined following culture for 90 min in a blind well chamber. Phagocytosis was assayed after co-culture of PMNs with sperm for 60 min. In the presence of ≥ 5% boar seminal plasma, chemotactic activity of PMNs was reduced (P < 0.05) in both pigs (from 1126.1 to 934.2-1009.1 cells/mm2) and in cows (from 1067.1 to 768.9-800.0 cells/mm2). Furthermore, ≥ 5% boar seminal plasma reduced (P < 0.05) leukocyte phagocytosis in pigs (26.2-32.1%) and cows (27.2-30.0%) compared to controls (41.7 and 42.1%, respectively). Although 20% hen's egg yolk increased (P < 0.05) chemotactic activity of PMNs in pigs (from 790.4 to 1006.1 cells/mm2) and cows (from 789.9 to 953.5 cells/mm2), egg yolk increased (P < 0.05) phagocytotic activity of porcine PMNs (from 24.3 to 33.8%), but not the activity of bovine PMNs (15.1 vs 15.8% in controls). Boar seminal plasma and caffeine reduced (P < 0.05) the egg yolk-induced increase in chemotaxis in both species (from 988.6 to 795.2 or 813.2 cells/mm2 in pigs and from 953.5 to 779.4 or 833.8 cells/mm2 in cows), and phagocytotic activities of PMN (from 33.8% to 15.2 or 13.3%) only in pigs (but not in cows; 11.2-15.1%). In conclusion, hen's egg yolk increased chemotactic activity of PMNs in both pigs and cows, whereas egg yolk increased only phagocytosis of PMNs in pigs, but not in cows. Even in the presence of egg yolk, boar seminal plasma and caffeine significantly reduced chemotactic activity of PMNs in pigs and cows, and phagocytotic activity of porcine PMNs.