Abstract: A method of preferentially delivering an active agent to an immune cell, such as a myeloid progenitor cell, a dendritic cell, a monocyte, a macrophage or a T-lymphocyte, or other cell type restricted to a functional organ system or an anatomic entity, of a mammalian subject by administering a lipid-drug complex to the subject. The lipid-drug complex is comprised of an active agent, such as a drug, and an outer surface with a targeting ligand that binds a marker on the surface of the immune cell or other cell type that is infected with or susceptible to infection with an infectious agent. The other cell type that is infected with or susceptible to infection with an infectious agent may belong to a malignant tumor or a part of the immune system contributing to the development, maintenance, or exacerbation of an autoimmune disease or chronic inflammatory disease.