Macaque blood-derived antigen-presenting cells elicit SIV-specific immune responses

Natural blood-borne antigen-presenting cells (APCs) were tested for their a bility to augment antigen presentation for SIV vaccines. Fibrocytes and mon ocyte-derived dendritic cells (DCs) were isolated from multiple Macaca fasc icularis. Macaque fibrocytes displayed the characteristic cellular morpholo gy and stained positive for CD34 and collagen, as observed in human and mur ine fibrocytes. Macaque DCs were generated from monocytes by culturing in g ranulocyte-macrophage colony stimulating factor and interleukin-4 (IL-4). T wo days after maturation, cells were enriched for the DC marker CD83. Fibro cytes and DCs were each transfected with green fluorescence protein express ion plasmids or DNA expression vectors encoding all of the SIVmne structura l and regulatory genes. Autologous DCs were reinfused into macaques subcuta neously (sc) following transfection; mixing with recombinant SIV antigens o r inactivated whole SIV in vitro; or mock-treatment. Autologous monocyte-de rived DCs pulsed with whole inactivated SIV were re-infused and elicited ce llular and/or humoral responses in vivo in eight of ten vaccinated macaques .