Ken-ichi Asai

Predominant subpopulations of T lymphocytes in the mammary gland secretions during lactation and intraepithelial T lymphocytes in the intestine of dairy cows.

Lymphocytes obtained from mammary gland secretions (MGS) during lactation or the dry period of dairy cows were simultaneously analyzed and compared to ileal intraepithelial lymphocytes (IEL) and peripheral blood lymphocytes (PBL) using monoclonal antibodies (mAb) specific for bovine leukocyte differentiation antigens. The T-lymphocytes of MGS during lactation and those in IEL were predominantly CD8(+), while T-cells in MGS during the dry period were predominantly CD4(+). In addition, the proportion of gamma delta T-cells in MGS during lactation and IEL was fairly high. A large percentage of CD8(+) cells and T-cells coexpressed the activation molecule, ACT2, yielding a high proportion of ACT2(+) CD8 T-cells and ACT2(+) gamma delta T-cells, in MGS during lactation and IEL. However, both types of cells were found at an extremely low level in MGS during the dry period and in PBL. Thus, the predominant T-cell populations in MGS during lactation are phenotypically similar to those in IEL in the intestine.

Inflammatory responses of bovine polymorphonuclear neutrophils induced by staphylococcal enterotoxin C via stimulation of mononuclear cells.

ABSTRACT To elucidate the pathological roles of staphylococcal enterotoxin C (SEC) in bovine staphylococcal mastitis, a histopathological analysis of SEC-inoculated mammary glands was performed. SEC-inoculated mammary glands exhibited interstitial inflammation, and the leukocytes that migrated into the gland were predominantly polymorphonuclear neutrophils (PMN). In the gland cistern tissues dissected from SEC-inoculated mammary glands, epithelial cellular degeneration was observed. We also investigated the physiological effects of SEC on PMN in vitro. PMN migration was induced by culture supernatant of SEC-stimulated peripheral blood mononuclear cells (S-PBMC sup) but not by that of nonstimulated PBMC (N-PBMC sup). The concentration of interleukin-8 was significantly (P < 0.05) higher in S-PBMC sup than N-PBMC sup, and a significantly (P < 0.05) higher mRNA expression of growth-regulated oncogenes was detected in SEC-stimulated PBMC than in nonstimulated PBMC. Milk PMN collected from SEC-inoculated mammary glands produced more than 2 times the amount of superoxide at 1 day postinoculation (dpi) than at 0 dpi in the presence of phorbol 12-myristate 13-acetate (PMA). PMN cultured with S-PBMC sup for 24 h also produced significantly (P < 0.05) larger amounts of superoxide than those cultured with N-PBMC sup in the presence of PMA. Moreover, S-PBMC sup induced the long-time survival of PMN. These results indicate that SEC induces the activation of PMN via the stimulation of mononuclear cells.

Differential gene expression of cytokine and cell surface molecules in T cell subpopulation derived from mammary gland secretion of cows

Problem:  As T cell subpopulations in the mammary gland secretion (MGS) of cows dynamically vary through the lactation cycle, their functional analysis is important to understand the mammary immune responses.