Bone marrow is a hematological and immunological organ that provides multiple immune cells, including B lymphocytes, and thus plays a critical role in the efficacy of vaccine. We previously demonstrated that Bordetella (B.) bronchiseptica antigen has high immunogenicity in spleen cells, a peripheral immune organ. In this study, we investigated the immunogenicity of B. bronchiseptica antigen in bone marrow cells, a central immune organ. B. bronchiseptica antigen increased the cellular activity of bone marrow cells and significantly enhanced the production of nitric oxide, IL-6, and TNF-¥�. Bone marrow cells primed with B. bronchiseptica antigen in vivo were harvested and stimulated with the same antigen in vitro. The stimulation of B. bronchiseptica antigen significantly increased the cellular activity and proliferation rate of the primed cells. B. bronchiseptica antigen also greatly induced the production of antigen-specific antibody in the primed cells. Taken together, the present study demonstrated that B. bronchiseptica antigen can stimulate bone marrow cells, a central immune organ, and recall the immune response of the primed bone marrow cells.

Systemic administration of dexamethasone led to a significant reduction in the size of the tuberculin reaction in response to intradermal injection of bovine purified protein derivative in 18 cattle experimentally sensitized to Mycobacterium bovis (P < 0.01) and 8 cattle naturally infected with M bovis (P < 0.001). The reaction in 6 of the 7 M bovis-infected cattle that received dexamethasone was classified as negative for the standard interpretation of the single intradermal comparative tuberculin test. Significantly fewer BoCD2+ (P < 0.05) and BoCD4+ T cells (P < 0.001) were present at the reaction site and in blood of dexamethasone-treated cattle, compared with untreated control cattle. Significantly fewer cells expressing the interleukin-2 receptor and WC1+ gamma delta T cells (P < 0.001), and a significantly greater number of cells expressing the ACT2 antigen (P < 0.05) were found at the reaction site in dexamethasone-treated cattle than in controls. The number of BoCD8+ T cells at the reaction site and in blood was not significantly affected by administration of dexamethasone. In vitro production of interferon-gamma by lymphocytes incubated with bovine purified protein derivative also was significantly lower (P < 0.01) in the dexamethasone-treated cattle.