Cooperative effects of gamma-interferon and 1α, 25-dihydroxyvitamin D3 on in vitro differentiation of the blast cells of RAEB and RAEB-T

We added recombinant human gammainterferon (γ-IFN) and 1 α, 25-dihydroxyvitamin D3 (1 α, 25 (OH)2D3) to the bone marrow cells from six patients with RAEB or RAEB-T in liquid suspension cultures. After cultivation for 7 to 9 days, numerical, morphological and functional changes of the cells were assessed. γ-IFN and 1 α, 25 (OH)2D3 additively suppressed cell growth, especially the number of blast cells decreased. The expression of α-naphthylbutyrate esterase (NBE) activity appeared to be promoted but that of naphthol AS-D chloroacetate esterase (NAE) activity was apparently suppressed by the addition of γ-IFN and/or 1 α, 25 (OH)2D3. The percentage of NBT reduction-positive cells and latex-phagocytizing cells was only slightly increased by both agents. These results indicate that γ-IFN and 1 α, 25 (OH)2D3 cooperate to induce monocytoid differentiation of the patients' blast cells. Combination therapy with both agents merits further study.