Bovine dendritic-cell subsets in lymphoid and non-lymphoid tissues: work in progress

Bovine dendritic-cell subsets can be readily identified in flow cytometry by staining for Flt3, CD4 and CD13. While this gating strategy could be confirmed by bulk RNA-seq of subsets sorted from peripheral blood mononuclear cells, it remains to be determined if the same gating strategy can be applied to gate on cDC1, cDC2 and pDC within lymphoid and non-lymphoid tissues. With this preprint we aim to inform on the current status of phenotyping experiments performed on Flt3 ⁺ cells in mesenteric lymph nodes, spleen and lung of cattle. Distinct DC subsets can be gated in all tissues based on CD4 and CD13, with high frequencies of Flt3 ⁺ CD13 ⁺ cells (putative cDC1) detected in the lung. Further phenotyping performed on lymph node cells (in particular CADM1, CD26 and CD123) support the subset classification analogous to blood, with pDC being Flt3 ⁺ CD4 ⁺ CD13 ^- and cDC1 being Flt3 ⁺ CD4 ^- CD13 ⁺ . Heterogeneous expression of CADM1 and CD26 on Flt3 ⁺ CD4 ^- CD13 ^- putative cDC2 warrants further investigations.