Disclosed is a composition of matter comprising an OSK1 peptide analog, and in some embodiments, a pharmaceutically acceptable salt thereof. A pharmaceutical composition comprises the composition and a pharmaceutically acceptable carrier. Also disclosed are DNAs encoding the inventive composition of matter, an expression vector comprising the DNA, and host cells comprising the expression vector. Methods of treating an autoimmune disorder and of preventing or mitigating a relapse of a symptom of multiple sclerosis are also disclosed.