Relationship of cytotoxicity and interferon-inducing activity of polyriboinosinic acid. Polyribocytidylic acid to the molecular weights of the homopolymers.

The molecular size of poly I.poly C required for lysis of interferon-treated L cells was the same as the size required for induction of interferon in these cells. The size requirement for both interferon induction and toxicity for interferon-treated L cells resided in the poly I strand, while variations of the poly C strand size were without effect on interferon induction or cell lysis. The size of poly I.poly C required to induce interferon in primed L cells or primed primary rabbit kidney cells was the same as the size required to induce interferon in normal L cells or normal rabbit kidney cells. Again, these requirements proved more stringent for the poly [ strand than for the poly C strand. These data suggest that both primed and normal cells recognize the same molecular 'trigger' for interferon induction.