Characterisation of dendritic cell frequency and phenotype in bovine afferent lymph reveals kinetic changes in costimulatory molecule expression

The bovine afferent lymphatic cannulation model allows collection of large volumes of afferent lymph and provides an opportunity to study lymphatic cells trafficking from the periphery directly ex-vivo. The technique requires surgical intervention, but influence of the procedure or time post-surgery on cells trafficking in the lymph has not been well documented. Here, we measured the volume of lymph and number of cells/ml collected daily over a two week time-course. Animal to animal variability was demonstrated but no consistent changes in lymph volume or cell density were observed in relation to time post-cannulation. Cell populations (dendritic cells, αβ T-cells, γδ T-cells and NK cells) were analysed by flow cytometry at 1, 3 and 10 days post-cannulation (DPC) and a reduced percentage of γδ T-cells in afferent lymph was observed at 1 DPC. In addition, cell surface molecule expression by afferent lymphatic dendritic cells (ALDC) was assessed due to the key role of these cells in initiating an adaptive immune response. Co-stimulatory molecules CD80 and CD86 were upregulated by CD172a+ve ALDC early in the time-course, suggesting that the cannulation procedure and duration of experiment may impact the activation state of DCs in the naïve host. This should be considered when analysing the response of these cells to vaccines or pathogens.