Methods: We treated BEAS-2B human REC with increasing doses of IFN-beta or IFN-lambda1 alone or together, and measured expression of TF-ISG and a set of “canonical” ISG by qRT-PCR and western blot.
Results: Alone, IFN-beta and IFN-lambda each induced expression of the canonical ISG and a subset of TF-ISG. By contrast, while IFN-beta alone induced IRF1 expression, it was poorly induced by IFN-lambda1 alone. Saturating doses of the two IFNs together did not enhance peak ISG transcript expression greater than either alone. Western blots revealed that while IFN-beta alone induced early and transient IRF1 expression, it was lower but sustained (through 24h) after IFN-lambda1 alone. In contrast to transcripts, saturating doses of the two IFNs together enhanced expression of IRF1 protein at 2h, 4h, and 24h greater than either of them alone.
Conclusions: In REC, IRF1 is expressed early and relatively selectively in response to IFN-beta alone, and protein expression was enhanced after treatment with both IFNs together. IRF1 may mediate non-redundant qualitative functional responses of REC to types I and III IFN.