Many naturally occurring polyanionic materials are known, each of which possesses its own set of physiological properties. Recently, a variety of synthetic polyanions have become available, and their physiological properties have been compared with the naturally occurring polyanions. Probably the most widely investigated synthetic polyanion is the 1:2 regularly alternating cyclo-copolymer (DIVEMA) (Eq. 1) of divinyl ether (DVE) and maleic anhydride (MA), first discovered in these laboratories in 1951 [1], This material has been investigated extensively, both from the standpoint of its chemical structure [2] and its antitumor activity [3]. Although certain aspects of its structure remain to be determined [4], it has been shown to possess a wide spectrum of biological activity [5] and is an interferon inducer [3]. Many structural modifications of DIVEMA have been synthesized which also possess antitumor activity and interferon-inducing capability [6].