DEAE-DEXTRAN AND INTERFERON PRODUCTIONmetabolizable fatty materials, viz., lipoid granulomata with gradual disappearance of oil cysts, residual collection of phagocytic cells, and final disappearance of reactions after some months. There was no evidence that adjuvant 65 would be likely to cause abscess or nodule formation. A test for teratogenicity in rabbits given adjuvant 65 emulsified preparations, or their aqueous counterparts on the eighth day of pregnancy revealed no apparent effects on fetal development.In vitro and in vivo production of interferon (IF) has been recently reported using double-stranded polynucleotides as inducers (6). The present note will describe the influence of diethylaminoethyl dextran ( DEAlEdx) on IF production by L cells treated with double-stranded synthetic polyinosinic-polycytidilic acid (1:C).Maderials and Methods. Mouse L cells (CCL-1 strain) were grown in loosely stoppered vertical 16 )( 100-mm tubes in humidified 5% COa environment at 37°C. Eagle's medium supplemented with 10% calf serum was used for the growth. The Same medium supplemented with 2% calf serum was used during the experiments. All the experiments were carried out in a COZ incubator at 37OC. The IF was titrated by plaque reduction assay using L cells and Semliki Forest virus (SFV as the challenge virus. Antiviral resistance was determined by inhibition of yield of SFV in a single growth cycle as previously reported ( 2 ) . DEAE-dx 0.015% was added to the nutrient agar over lay medium to inactive agar-inhibi,tors of SFV (3). Polyinosinic and Polycytidilic acids (Sigma Chemical Co.) were processed as indicated by Field et al. (1) in order to obtain the double-stranded complex I: C.The DEAE-dx (mol. wt. 2 X 106, Pharat Glasgow University Library on June 30, 2015 ebm.sagepub.com Downloaded from

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Summary Interferon production by mice treated with the double-stranded polynucleotide complex I:C is increased up to 30 times by the presence of DEAE-dextran in injected I:C solutions. Consistent amounts of circulating IF could be detected only 90 min after treatment. The highest levels of circulating IF were produced within 3 hr after treatment with I:C (20 µg/mouse) and DEAE-dx (200 µg/mouse). The highest levels of circulating IF were maintained during a 10- to 12-hr period following a single stimulation. Repeated treatment of mice with I:C and DEAE-dx after the disappearence of previously induced IF were followed by new rises of IF production. If stimulation was repeated at the times when the previously induced level of circulating IF was still high, it was possible to maintain this level during the whole period of study (39 hr). Protection against challenge with Columbia SK virus was much higher in mice treated with repeated doses of inducer (90% survival) than in mice treated with a single dose of inducer (50% survival).