A method of reducing the immune suppressor activity of myeloid cells is disclosed. The method comprises contacting myeloid cells with an effective amount of an agent which specifically reduces the amount and/or activity of myeloid cells expressing both Triggering Receptor Expressed On Myeloid Cells 2 (Trem2) and Transmembrane glycoprotein NMB (Gpnmb). The method can be used for treating cancer. Antibodies and bi-specific antibodies are also disclosed.