Leukocyte immunoglobulin-like receptor subfamily A member 4 (LILRA4/ILT7/CD85g) is a marker of plasmacytoid dendritic cells (pDCs), which are reported to be a major source of the abnormally high levels of IFNα associated with autoimmune diseases. Targeting LILRA4 with therapeutic antibodies to promote killing of these IFNα-producing pDCs is being investigated as a novel approach to alleviating the symptoms of autoimmune diseases. LILRA4 is an immunoglobulin-like protein preferentially expressed on the surface of human plasmacytoid dendritic cells (pDCs). It interacts with bone marrow stromal cell antigen 2 to control the Toll-like receptor (TLR) driven response by pDCs to viral infection. It may also be involved in modulating pDC-tumour interactions. pDCs are a source of the excess IFNα which drives autoimmune disease symptoms.