Leukocyte response of bovine mammary gland to injection of killed cells and cell walls of Staphylococcus aureus.

Injection of mammary glands of cows with heat-killed staphylococcal cells, staphylococcal cell walls, or distilled water induced leukocytosis. The magnitude of leukocytic response to staphylococcal antigens in cows of each treatment group depended on the extent of previous experience with staphylococcal cell materials. The 2nd intramammary injection produced greater reactions than did the 1st, and the 1st injection in cows previously parenterally vaccinated with killed cells in oil-water adjuvant produced responses comparable with those elicited by the 2nd intramammary injection in nonvaccinated cows. The implications that these changes have toward understanding the pathogenesis of, and immunity to, staphylococcal mastitis were discussed.