Equine monocyte-derived macrophages (A) and dendritic cells (B) generated ex vivo. Isolated peripheral blood monocytes were stimulated (dendritic cells) or not (macrophages) with rEq IL-4 and rHuGM-CSF in DMEM-F12, 5% bovine growth serum. The photomicrogaphs depict the differentiation of adult horse and foal macrophages and dendritic cells in culture. A and B = day 5 adult horse and foal macrophages, respectively; A' and B' = day 5 adult horse and foal dendritic cells, respectively – note their extended shape in contrast to the round macrophages; C = day 6 dendritic cells adhered to the plastic of the cell culture plate; C' = a group of day 6 dendritic cells floating in the supernatant of the cell culture – note the presence of small dendrites. Bars indicate 50 μm.