Delivery to macrophages of interleukin 3 loaded in mouse erythrocytes

Mouse carrier erythrocytes containing I-125-interleukin 3 have been prepare d and treated with band 3 crosslinking reagents. The incorporation of inter leukin 3 by hypotonic treatment into mouse erythrocytes reached levels of a bout 15% of the interleukin 3 added to the medium being predominantly prese nt in the cytosolic fraction (73%). Uptake fell to about 7.4% when using th e same conditions but omitting hypotonic shock. The interaction of band 3 c rosslinked interleukin 3 loaded erythrocytes with macrophages was also stud ied. A high level of incorporation of interleukin 3 into macrophages was ob served either from band 3 crosslinked, interleukin 3-loaded erythrocytes or from interleukin 3 loaded erythrocytes. The observations encourage the vie w that the system may be able to deliver and target cytokines and other gro wth factors to macrophages.