The effect of retinoids on CFU-GM from normal subjects and patients with myelodysplastic syndrome

Five retinoid analogues differ in their effects on the growth of CFU-GM from normal human marrow. At concentrations above 10(-6) M all have inhibitory activity. This is maximal with 13-cis-retinoic acid. At lower concentrations the effect of retinoids is usually to reduce clone size rather than clone numbers though 10(-8)-10(-7) M etretinate increases clone size. The incubation of marrow cultures in the presence of 10(-6) M all-trans retinoic acid showed that in normal subjects colony counts are never reduced to less than 45% of the control value and total clone counts to less than 70% of the control value. In cultures from patients with myelodysplastic syndrome 20 out of 34 cases showed a greater inhibition of colony numbers than normal and 14 out of 35 cases showed a greater reduction in total clone numbers than normal. The results suggest that CFU-GM from some patients with myelodysplastic syndrome may have a greater sensitivity than normal to the inhibitory effect of retinoic acid.