Impaired α‐interferon production and natural killer activity in blood mononuclear cells in myelodysplastic syndromes

The producibility of interferon (IFN)-alpha, which indicates one of the functions of large granular lymphocytes (LGL), was impaired at a high frequency in myelodysplastic syndrome (MDS) patients. However, IFN-alpha production in refractory anaemia, which is a subtype of MDS, was almost normal. In contrast, abnormality has not been observed in either proliferative response or the production of IFN-gamma of T-cells by stimulation with PHA. NK activity of peripheral blood mononuclear cells (PBMC) from MDS patients was generally low and was not augmented by IFN-alpha treatment. These results indicate that, in addition to the abnormality at the level of haematopoietic tissues, LGL among PBMC may be impaired in MDS patients.