Enhancement of Chemotactic Response of Polymorphonuclear Leukocytes into the Mammary Gland and Isolation from Milk

Intramammary infusion of saline containing .1% glycogen resulted in diapedesis of numerous leukocytes (93% polymorphonuclear leukocytes) into milk. Direct microscopic somatic cell counts of primary milk 11 h after infusion with 100 ml of either saline containing .1% glycogen, saline, distilled water, or noninfused averaged 4.17, 1.06, .05, and .10 X 10(6) cells/ml of milk. Four times more polymorphonuclear leukocytes were isolated from residual milk (6.1 X 10(9) cells) collected 11 h following infusion than from primary milk (1.5 X 10(9)). The polymorphonuclear leukocytes isolated from either the primary or residual milk collected 11 h after infusion of saline containing .1% glycogen phagocytosed Staphylococcus aureus with great avidity. Sixty-eight percent of a culture of heat-killed phosphorus-32-labeled Staphylococcus auresu (400 X 10(6)) were phagocytosed within 60 min by 25 X 10(6) polymorphonuclear leukocytes. When isolated polymorphonuclear leukocytes were incubated with live Staphylococcus aureus, 98% of the ingested organisms were killed. Isolation of polymorphonuclear leukocytes from residual milk 11 h after intramammary infusion of saline containing .1% glycogen will provide large numbers of polymorphonuclear leukocytes for in vitro studies of the cellular defense of the mammary gland.