Abstract: The present invention discloses a novel liposome composition wherein phosphatidyl ethanolamine, cholesteryl hemisuccinate, and cholesterol in a ratio of 7:4:2 allow for the efficacious administration of a therapeutic agent to a macrophage. The liposomes of the present invention are stable at physiological pHs, while at the same time being fusogenic at acidic pHs. This property allows for the delivery of the therapeutic agent into the cytosol, and subsequently the nucleus, of the macrophage. The liposome composition disclosed herein is useful in the treatment of macrophage associated diseases or conditions.