Dendritic cells (DCs) are rare events in the blood and there are few specific antibodies available to identify them. They are best identified by exclusion of all other lineages and are referred to as Lin-. To achieve this blood cells are labelled with a cocktail of antibodies specific for T, B and NK cells as well as monocytes and granulocytes. Mononuclear cells that are negative for these antibodies are then deemed to be DCs. DCs express high levels of class II HLA molecules so they can be further identified by gating on this and the surface expression of various antigens on the DCs can then be determined.