Abstract: A method for isolating a desired protein which comprises: providing a host cell expressing the desired protein as an insoluble aggregate; culturing the host cell with an effective mount of Cu.sup.++ ; disrupting the host cell producing a lysate; incubating the insoluble fraction non-disulfide-bond reducing or non-copper competing chaotropic conditions to solubilize contaminants; separating the insoluble from the soluble fraction; and exposing the insoluble fraction to disulfide-bond reducing or copper competing chaotropic conditions to solubilize the desired protein.

Abstract: Shipping fever, and other stress-related diseases in livestock, are treated by administration of a microencapsulated composition comprising IL-2 conjugated with a polyoxyethylene polymer, and mixed with a release-modulating amount of humen serum albumin. The microcapsules are administered parenterally, and release an effective amount of conjugated IL-2 continuously over a period of 14-30 days. These microcapsules are also effective in the treatment of cancer in mammals.