Maintenance of LMP-1 expression by hIL-10 in ER/EB2-5 cells after estrogen removal. (A) ER/EB2-5 cells were cultured in the presence or absence of estrogen or in the presence of 50 ng/mL hIL-10 for 3 days. EBNA-2, EBNA-1, and LMP-1 expression were assayed in the same total cell extracts by SDS-PAGE and immunoblotting. The lower expression of EBNA-1 in the estrogen-treated ER/EB2-5 cells was not reproducible and was probably due to difference in loading of the sample. (B) Flow cytometric analysis of the CD21, CD80, and HLA-II antigens in the estrogen-starved, hIL-10-treated (50 ng/mL, 3 days) ER/EB2-5 cells. The fluorescence intensity in the FL2 channel was measured (logarithmic amplification) and analyzed with the CellQuest Pro program. On the histogram plots the shaded areas represent the background fluorescence of the secondary Ab-stained cells, whereas the solid black lines denote the specific staining of the untreated and hIL-10-treated cells. The mean fluorescence intensity is indicated. B958 LCL and Jurkat cells were used as positive and negative staining controls, respectively (not shown).