Effect of body condition score of the dairy cow on the in vitro immune response of peripheral blood mononuclear cells to progesterone stimulation.

Immune function in cows is closely associated with their physical and hormonal conditions. In order to clarify the relationship between the body condition score (BCS) of lactating dairy cows and the immune response to progesterone (P(4)) in vitro, we examined whether lower BCS in dairy cows affects the responsiveness of peripheral blood mononuclear cells (PBMCs) to P(4) added in to culture medium. Forty-two non-pregnant healthy Holstein dairy cows were examined at 61 to 120 days after calving. The cows were divided into the following two groups; Low BCS group (N=20), which had a BCS of less than 2.25, and a Control group (N=22), which had a BCS over 2.75. PBMCs were stimulated with P(4) (1 microg/mL) and/or phytohemagglutinin (PHA), and the levels of cytokine mRNA were analyzed. In the Low BCS group, a significantly lower IFN-gamma level was stimulated by PHA only compared with the Control group. The combination of P(4) and PHA significant decreased the IFN-gamma/IL-4 ratio in the Control group, but this reaction was not found in the Low BCS group. Our data indicated that expression of IFN-gamma mRNA was basically lower in the low BCS dairy cows and that addition of P(4) did not suppress the cellular immune function in these cows. In this study, we observed that P(4) reduced the cellular immune response in the adequate BCS cows, whereas immunosuppression by P(4) was not found in the PBMCs of the low BCS cows, which already had a lower level of immune function.

Comparison of the peripheral blood leukocyte population between Japanese Black and Holstein calves.

Japanese black (JB) calves have greater susceptibility to infectious diseases compared to Holstein (Hol) calves. In order to clarify the differences in cellular immune status between JB and Hol calves, the leukocyte population and lymphocyte proliferative ability were analyzed. In total 200 healthy calves, 1 day to 14 weeks of age, were examined: 105 JB and 95 Hol calves. Lower numbers in peripheral blood and percentage in peripheral blood mononuclear cells of CD3(+)TcR1-N12(+) T cells and major histocompatibility complex class-II(+)CD14(-) B cells were observed in the JB compared to the Hol. The percentage of TcR1-N12(+)CD25(+) T cell in the JB was significantly lower than that of the Hol at 4-6, and 8-10 weeks. Interleukin (IL)-2 sensitivity in the JB was lower than that in the Hol, and significant differences were observed in age groups of 6-8 weeks and 10-14 weeks. These findings indicated that the lower numbers of γδ T cells and B cells in the JB compared to the Hol might be associated with the specificity of the immune systems in JB calves.

Relationship between diarrhea and peripheral leukocyte population in neonatal Japanese black calves.

Neonatal Japanese Black (JB) calves show a high incidence of diarrhea. The objective of this study was to analyze the immune cell populations of neonatal JB calves in detail and examine its correlation with the incidence of diarrhea immediately after birth. Understanding the immune cell populations is helpful in clinics in order to determine the condition of the immune system for prevention of diseases. Blood samples were obtained from JB calves on the day of birth. The peripheral leukocyte populations were analyzed separately for calves that had diarrhea within 2 weeks after birth (diarrhea group; n = 26) and for calves without diarrhea (control group; n = 74). The numbers of the peripheral blood CD3(+)TcR1-N12(+) and CD8(+) T cells were significantly lower in the diarrhea group compared with the control group. These findings suggest that the congenital lower peripheral γδ and CD8(+) T cells results in a high risk of diarrhea in neonatal JB calves.

Effect of parity on lymphocytes in peripheral blood and colostrum of healthy Holstein dairy cows.

Investigation of the bovine systemic and mammary gland immune cells at calving might provide crucial information about the susceptibility of the mammary gland to infection. This study investigated the leukocyte population and cytokine mRNA levels in peripheral blood mononuclear cells (PBMCs) and colostrum mononuclear cells (CCs) obtained from healthy cows soon after calving. Fifty dairy cows that did not show clinical diseases were divided into 4 groups on the basis of parity: heifer (group 1, n = 10), 2nd calving (group 2, n = 11), 3rd calving (group 3, n = 14), and more than 3rd calving (group 4, n = 15). In the peripheral blood the numbers of CD3(+)TcR1-N12(+), CD3(+), CD4(+), and major histocompatibility complex class II(+)CD14(-) lymphocytes were significantly higher in group 1 than in group 4, whereas in the colostrum the percentages of CD4(+) and CD4(+)CD26(+) lymphocytes and the CD4(+)/CD8(+) ratio were significantly lower in group 1 than in group 4. There were no significant differences in the cytokine mRNA levels of PBMCs among the 4 groups; however, in the CCs the ratio of interferon gamma to interleukin 4 was significantly lower in group 1 than in group 3. These results suggest that the cellular immune function of PBMCs is lower, whereas mammary gland immune cells are more active, in cows with higher parity compared with heifers at calving.