DNA AS AN ADJUVANT - CAPACITY OF INSECT DNA AND SYNTHETIC OLIGODEOXYNUCLEOTIDES TO AUGMENT T-CELL RESPONSES TO SPECIFIC ANTIGEN

How strong adjuvants such as complete Freund's adjuvant (CFA) promote T cell priming to protein antigens in vivo is still unclear. Since the unmethylated CpG motifs in DNA of bacteria and other nonvertebrates a re stimulatory for B cells and antigen-presenting cells, the strong ad juvanticity of CFA could be attributed, at least in part, to the prese nce of dead bacteria, i.e., a source of stimulatory DNA. In support of this possibility, evidence is presented that insect DNA in mineral oi l has even stronger adjuvant activity than CFA by a number of paramete rs. Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs mimic the effects of insect DNA and, even in soluble form, ODN s markedly potentiate clonal expansion of T cell receptor transgenic T cells responding to specific peptide.