Interférons humains induits in vitro par des polynucléotides synthétiques

Abstract

Human interferons induced in vitro by synthetic polynucleotides Optimal conditions of in vitro production of human interferon were studied, employing polyinosinic acid and polycytidylic acid complexes as inducers. Two cellular sources were utilized: leukocytes and the amniotic membrane. Greater amounts of interferon were obtained from leukocytes. In this system as little as 0.01 μg/ml of poly I + poly C was sufficient for the induction of detectable amounts of interferon in the extracellular medium. The production of interferon increased more than 100-fold when cells were pretreated with DEAE-dextran at a concentration of 10 μg/ml. In the presence of DEAE-dextran (10 μg/ml of the complex in leukocyte suspensions 10 7 cells/ml) titres of interferon between 1024 and 2048 were obtained. Under the same conditions, interferon titering 64 was recovered from the amniotic membrane. Physicochemical and biological properties of the polynucleotide-induced interferons were determined and found to be the same as those for viral-induced interferons. The molecular weight of polynucleotide-induced leukocyte interferon was 25000 (± 10 %). The same values were found using para influenza 1 (Sendaï) virus as inducer. Pre-treatment of leukocytes with actinomycin D (1 μg/ml, 1 h) reduced the production of interferon by 75 %. Biological activity of interferon in amniotic cells was inhibited 90 % by pretreatment with actinomycin D (0.1 μg/ml). The mixing curve of poly I + poly C was studied correlating the hypochromic effect and interferon production. The largest amounts of interferon and maximal hypocromic effect were found when poly I and poly C were mixed in equimolecular proportions. These results agree with the hypothesis that the double-stranded configuration of the RNA molecule is essential for the induction of interferon.