The effects of interleukin-8 (IL-8) on bovine mammary functions such as milk protein secretion were evaluated. Recombinant bovine IL-8 (rBoIL-8; 5, or 25/ μg per milk cistern) or placebo saline was individually infused into a front mammary milk cistern on each of six cows at the beginning of drying-off (cessation of milking). The milk cistern fluid was collected at –1, 0, 0.4, 1, 3, 7, 14 and 30 days after infusion. In the mammary glands infused with 25 μg of rBoIL-8, increases in SCC and the concentrations of serum proteins such as serum albumin and IgG2, and decreases in the concentrations of casein and β-lactoglobulin, were observed from 1 to 30 days after the infusions. In the mammary glands infused with 5 βg of rBoIL-8, these changes were smaller than those in the glands infused with 25 βg of rBoIL-8. Lactation was hormonally induced in the cows at 90 days after infusion. In the hormonally induced lactation, the quantity and quality of the milk recovered to the levels recorded before the rBoIL-8 infusion. These results indicated that rBoIL-8 could reversibly induce leukocytes and serum proteins such as IgG2 and suppress the secretion of milk specific proteins such as caseins. (Clinical Biochemistry Section, Hokkaido Research Station TEL +81-11-851-5226)
Reference:
Watanabe et al. (2000) J. Vet. Med. B 47:653-662.
