Cellular immunity in the mammary gland with particular reference to T, B lymphocytes and macrophages

Initial steps were carried out in the identification of T and B-cells in milk of sheep at all stages of lactation and some studies were made in the interactions of these cells with mammary macrophages with in vitro assays for cellular immunity. It was found that the predominant mononuclear cell in mammary secretion was the macrophage but lymphocytes were also found at relatively constant levels throughout the lactational cycle. T-cells were identified (E-rosettes) but their percentage fluctuated within wide limits (0-80%). There was no discernible trend associated with stage of lactation. B-cells also fluctuated widely but it was evident that contaminating monocytes reduced the accuracy of the count. A functional characteristic of macrophages, the enhancement of lymphocyte mitogenesis, appeared to operate with macrophages from the mammary gland. Furthermore, mammary macrophages were shown to have potentially microbicidal super oxide which was demonstrable in a chemiluminescence assay.