Effect of type I IFNs subtypes on J2E cell apoptosis.

(A) Apoptosis of J2E cells in response to stimulation with IFN subtypes (100 IU/mL), in the absence of serum, at 24 hours by TUNEL assay. Apoptotic cell bodies stained with diaminobenzidine (DAB, black) and cells counterstained with hematoxylin (gray). Original magnification, × 40. (B) The percentage of positive staining apoptotic cells was determined by light microscopy. (Statistical significance compared with unstimulated J2E cells, *P ≤ .05, mean ± SE, n = 3.) (C) At 6 and 24 hours after stimulation with 1000 IU/mL IFN, in the absence of serum, DNA fragmentation (≤ 6 kb) was determined in J2E cells. Control cultures were unstimulated.