Bovine interleukin-1 expression by cultured mammary epithelial cells (MAC-T) and its involvement in the release of MAC-T derived interleukin-8

MAC-T cells, an established bovine mammary epithelial cell line, were utilized to investigate both expression of interleukin-1 (IL-1) mRNA and secretion of IL-1 after Escherichia coli lipopolysaccharide (E. coli LPS) stimulation. In addition, recombinant human IL-1beta, recombinant human IL-1 receptor antagonist (IL-1ra) and a neutralizing goat antibody against type I human IL-1 receptor were used to study the involvement of IL-1 in the release of IL-8. The expression of MAC-T derived IL-1alpha mRNA was correlated to production of IL-1alpha protein as measured by an IL-1alpha sandwich ELISA. Secretion of IL-1alpha was dose- and time-dependent, with a maximal level of 600 pg/ml detectable upon 2-h stimulation with 20 microg of LPS per ml. IL-1ra and the neutralizing antibody significantly blocked the ability of IL-1beta to stimulate secretion of IL-8 by MAC-T cells. During this study, we have demonstrated that MAC-T cells secrete IL-1 in response to LPS stimulation and IL-1 is an important mediator for the release of the bovine IL-8 by MAC-T cells. These results further indicate the potential importance of mammary epithelial cells as a source of immunoregulation in the mammary gland via cytokine elaboration.