A, CD80-Fc induces transcription of EGR1/2/3/4. CD3+ cells were isolated by negative selection from the blood of healthy human donors, activated with PHA for 72 hours, and then either untreated or incubated for two hours with isotype control mAb, agonist CD28 mAb, TROY-Fc, or CD80-Fc. RNA was then isolated, converted into cDNA, and the DNA analyzed by qRT-PCR for EGR1/2/3/4. Values were normalized to β-actin expression. Results are shown as fold change in expression level compared to untreated T cells. Statistical analysis was performed using Student’s t test. Data are from one of three independent experiments. B, CD3+CD28+ Jurkat cells were treated for 30 min at 37OC with isotype mAb, agonist CD28 mAb, TROY-Fc, or CD80-Fc. Cells were then fixed and permeabilized, and stained with mAbs to pMAPK or pNF-κB followed by anti-rabbit IgG-FITC. C, Jurkat cells were untreated or treated for 30 min with agonist anti-CD28 mAb and then lysed and analyzed by western blot for phosphorylated MAPK and NFκB. Data for B and C are representative of one of two and one of three independent experiments, respectively.