We investigated the effect of intramammary infusion of recombinant bovine (rb) cytokines on the mononuclear cell populations in udders and measured the score of the California mastitis test (CMT). The udders of 21 cows with naturally occurring subclinical mastitis were infused with recombinant bovine granulocyte-macrophage colony-stimulating factor (rbGM-CSF), recombinant bovine interleukin 8 (rbIL-8), or a combination of both. Seven days after infusion of the control solution without any cytokines, the above cytokines were infused into the udders. Milk samples were collected from the udders on days 0, 1/4, 1, 2, 3, 7, and 14 after the infusions. The CMT score rose sharply between days 1/4 and 2, followed by a smooth decline to low pre-infusion levels between days 7 and 14. Interestingly, the percentage of CD14+ cells increased on days 1 and 2 after infusion of only rbGM-CSF. Subsequent to this increase in the percentage of CD14+ cells, the percentages of CD4+ and CD8+ cells also increased on days 2 and 3, suggesting that the infusion of rbGM-CSF enhanced cellular immunity in the mammary gland. In contrast, the percentages of CD4+ and CD8+ cells decreased on days 1/4 and 1 after infusion of rbIL-8 and the combination. However, the underlying mechanism of the decrease following combined infusion of both cytokines is not understood and needs to be addressed in future. Our results showed that intramammary infusion of rbGM-CSF induces an alteration in the mononuclear cell populations in milk. This observation indicates that rbGM-CSF may have the potential to be used as a therapeutic agent for subclinical mastitis of dairy cows.
(Research Team for Production Diseases, TEL +81-29-838-7708)
Reference:
Kiku, Y. et al. (2008) Mastitis Control: From Science to Practice, Wageningen Academic Publishers: p160.
