Mycobacterium bovis bacille Calmette-Guerin vaccination of cattle: activation of bovine CD4(+) and gamma delta TCR+ cells and modulation by 1,25-dihydroxyvitamin D-3

Setting: 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D-3) is a potent modulator of immune responses and may be beneficial in-the treatment of tuberculosis. Recent evidence suggest that 1,25(OH)(2)D-3 may affect T-dependent responses in cattle; however, mechanisms by which this vitamin modulates activation of bovine T cells are unclear. Objective: Determine the effects of 1,25(OH)(2)D-3 on the expression of CD25, CD44, and CD62L by bovine T cell subsets proliferating in response to antigen stimulation. Design: Antigen-specific recall responses of Mycobacterium bovis bacille Calmette-Guerin (BCG) vaccinated cattle were used as a model system to evaluate effects of 1,25(CH)(2)D-3 on the proliferation and activation of bovine T cell subsets. Results: CD4(+) and gammadelta TCR+ cells were the predominant T cell subsets responding to soluble crude M. bovis-derived antigens (i.e., purified protein derivative and a BCG whole cell sonicate) by proliferation and activation-induced alterations in phenotype. These subsets exhibited increased CD25 and CD44 mean fluorescence intensity (mfi) and decreased CD62L mfi upon antigen stimulation. Addition of 1,25(OH)(2)D-3 inhibited proliferation of CD4(+) cells and decreased the expression of CD44 on responding (i.e., proliferating) CD4(+) and gammadelta TCR+ cells. Conclusion: These findings suggest that the production of 1,25(OH)(2)D-3 by macrophages within tuberculous lesions would inhibit proliferation and CD44 expression by co-localized CD4(+) and gammadelta TCR+ cells. Published by Elsevier Ltd.