Oligonucleotide Sequences Required for Natural Killer Cell Activation

Based on the previous finding that certain 30‐mer single‐stranded oligodeoxyribonucleotides (oligonucleotides) having particular 6‐mer palindromic sequences could induce interferon‐alpha and ‐gamma, and enhance natural killer activity, the present study was carried out to clarify the entire relationship between the activity and the sequence of 30‐mer oligonucleotides. The results indicated that the activity depended critically on the presence of particular palindromic sequences including the 5 ‐CG‐3 motif(s). The size and the number of palindromes as well as the extra‐palindromic sequences also influenced the activity. An oligonucleotide with a 10‐mer palindrome and extra‐palindromic oligoguanylate sequences showed the strongest activity among the oligonucleotides tested.