Figure 1.

Activin A stimulates mouse DCs to express BAFF. (A) Effect of activin A on BAFF transcriptional levels in DC2.4 cells. DC2.4 cells (a mouse DC line) were treated with activin A (5, 10, and 20 ng/ml) for 24 h (left panel). Activin A (10 ng/ml) was added to the cell cultures for the indicated times (right panel). In all experiments, BAFF mRNA levels were determined by RT-PCR. Fold increase (Fold I.) values represent relative amounts of BAFF cDNA normalized to the expression of β-actin cDNA using Kodak Molecular Imaging software. (B) Effect of activin A on BAFF promoter activity. DC2.4 cells (1×10⁶) were transfected with the pBAFF reporter (1µg). Cells were then stimulated with activin A (10 ng/ml) and luciferase activity was determined 24 h later. Transfection efficiency was normalized by β-gal activity. Data are average luciferase activities of two independent transfections with ranges (bars). (C) Effect of activin A on BAFF secretion. DC2.4 cells were treated activin A (10 ng/ml). After 48 h of culture, supernatants were collected and the secreting form of BAFF was measured by ELISA. Data are means of triplicate samples±SEM. ^*p<0.05; ^**p<0.01. (D) Effect of activin A on the growth kinetics of DC2.4 cells. DC2.4 cells were cultured with activin A (10 ng/ml). Numbers of viable cells were enumerated by trypan blue exclusion. Data are means of triplicate samples±SEM.