Muramyl Dipeptide Can Influence Mammary Gland Lymphocytes

Mammary gland is important organ for all calf. The mammary gland of the bovine is divided lengthwise into left and right halves and is further divided into anterior and posterior quarters. Inflammation of the mammary gland is one of the most serious production diseases of dairy cattle. Lukocytes play an important role during mammary gland inflammation. During inflammation, leukocytes move from the blood to the mammary gland. Programmed leukocyte cell death plays an important role in the inflammatory response of the mammary gland. The study was implemented on eight healthy heifers in age 16 to 18 months. Each mammary gland in each quarter of the udder was injected with 20 ml phosphate buffered saline (PBS) with 500 mu g of muramyl dipeptide synthetic derivate. The lymphocytes obtained by lavages of mammary glands were analysed by flow cytometry and subsequently by software WinMDI 2.8. Proportion of apoptotic lymphocytes was enumerated by staining with Annexin-V and propidium iodide. The cytokine concentrations were determined using sandwich ELISA. Apoptosis of lymphocytes and concentration of TNF-alpha were peaked 48 hours following stimulation of the mammary glands by muramyl dipeptide. We have found high correlation in initial stage of mastitis between apoptosis of lymphocytes and TNF-alpha production especially in 48 hours after experimentally induced inflammation.