Fig. 1.
Effect of retinoic acid on DNA synthesis. Human B cells were isolated and stimulated with μ (37.5 μg/mL) and SAC (0.005%) as described in Material and Methods. Cells (0.75 × 106 cells/mL) were cultured in 96-well culture plates in triplicates. Retinoic acid (10 or 1000 nmol/L) was added at the indicated times (T) after stimulation. [3H]Thymidine incorporation (mean ± SD) was measured as described in Material and Methods. One representative experiment of three is shown. μ, F(ab′)2 fragment of rabbit antihuman IgM; SAC,Staphylococcus aureus crude cell suspension; RA, retinoic acid.