Effect of brefeldin A and cycloheximide on expression of FL by cultured T lymphocytes. T lymphocytes, purified from PB of a healthy donor, were cultured for 72 hours in serum-free medium in the absence or presence of brefeldin A or cycloheximide (both at 10 μg/mL). Flow cytometric analysis of cell surface FL was performed with anti-FL MoAb M5 followed by FITC-labeled goat antirat IgG. (Shaded area) FL expression in untreated cells; (solid line) FL expression in brefeldin A- or cycloheximide-treated cells, as indicated; (broken line) control staining with FITC-labeled goat antirat IgG.