Further Heterogeneity of Human α Interferon mRNA Species

Translationally active (in Xenopus oocytes) human α interferon (IFN) messenger RNA's (mRNA's) derived from Sendai virus-induced leukocyte cultures display a bimodal distribution of RNA lengths on electrophoresis through agarose-CH$_{3}$HgOH gels. The major population ($\alpha _{s}$) consists of mRNA of length 0.7 to 1.4 kilobases, while the minor population ($\alpha _{L}$) consists of RNA of length 1.6 to 3.5 kilobases. Induction of human leukocytes in the presence of 5,6-dichloro-1-β -D-ribofuranosylbenzimidazole (DRB; 100 micromolar) appears to inhibit the accumulation of IFN-$\alpha _{s}$ and to enhance that of IFN-$\alpha _{L}$ mRNA's (average length about 1.8 kilobases in preparations from DRB-treated cells). Interferons derived from the $\alpha _{s}$ mRNA's represent the group of previously recognized α interferons while the $\alpha _{L}$ interferons are distinguishable from this group by their lower heterospecific activity on bovine cells compared to human cells, their apparent slower mobility in sodium dodecyl sulfate-polyacrylamide gels, and their apparent heteroclitic response toward an antiserum to IFN-α.