Cyclosporin A (CyA) does not enhance CFU-c growth in patients with severe aplastic anaemia

8 patients with severe aplastic anaemia (SAA) in remission following immunosuppressive therapy were studied for CFU-c growth from unfractionated or E-rosette depleted (E-) bone marrow (BM) cells. Cyclosporin A (CyA) was added to unfractionated BM cells at a concentration of 1000 ng/ml. The mean number of CFU-c/10(5) BM cells plated was 6 +/- 6 from unfractionated BM cells, 28 +/- 20 from E-BM cells, and 8 +/- 7 from unfractionated BM cells supplemented with CyA. All patients had significant increase of CFU-c growth after E rosette depletion (overall P = 0.002). On the contrary, only 1 patient showed an increase of CFU-c growth after addition of CyA, and overall there was no difference between untreated and CyA treated BM cells (P = 0.7). These results suggest that addition of CyA to BM cells in vitro is not an effective means of enhancing CFU-c growth in SAA patients.