Differential distribution of WC1+ γδ TCR+ T lymphocyte subsets within lymphoid tissues of the head and respiratory tract and effects of intranasal M. bovis BCG vaccination

BCG vaccination of neonatal calves induces significant protection against bovine tuberculosis. The enhanced protection observed in neonatal calves may be linked to an enhanced capacity for IFNγ production by innate cells, including WC1+ γδ T cells, which constitute a major population in young cattle. Intranasal BCG vaccination of mice induces high levels of IFNγ in the lungs, which may enhance protection against subsequent challenge with virulent strains of mycobacteria. We used an intranasal BCG vaccination model in calves to study the effect on the distribution of WC1+ γδ T cells expressing two alternate forms of WC1: WC1.1 and WC1.2. These subsets of WC1+ γδ T cells have previously been shown to have a differential capacity for IFNγ secretion. Our results indicate that there is a selective expansion/recruitment of γδ T cells expressing the IFNγ-associated WC1.1 isoform in tissues of the lungs and upper respiratory tract following intranasal BCG vaccination.