Adjuvanticity of Mycobacterial RNA and Poly A:U for Induction of Experimental Allergic Encephalomyelitis in Guinea Pigs

Youmans and Youmans (1, 2) have reported that mycobacterial ribosomal or RNA preparations rival viable attenuated mycobacteria (H37Ra) in their capacity to engender cellular immunity to challenge with virulent mycobacteria (H37Rv). More recently, these workers have discovered mycobacterial RNA preparations to augment humoral as well as cellular immune responses (3). Concurrent studies by a number of investigators (4–7) have demonstrated synthetic polynucleotides to potentiate immune responses to a variety of antigenic stimuli. These and other studies have served to focus attention on the important role of microbial and synthetic double stranded RNA as immunobiologic adjuvants. Mycobacteria are a prerequisite adjuvant component for sensitization of guinea pigs to neuroantigens and regular induction of experimental allergic encephalomyelitis (EAE)3 in this animal species (8). While EAE-induction has been reported with mycobacterial lipid or lipopolysaccharide fractions and WaxD, as well as other microorganisms, none has equalled the biologic potency of killed whole mycobacteria for production of this experimental autoimmune disease (9–12).