Type I and type II T-cell profiles in aplastic anemia and refractory anemia.

Immune-mediated suppression of hematopoiesis has been considered the most important mechanism in the development of idiopathic aplastic anemia (AA) and some types of myelodysplastic syndrome (MDS). Using flow cytometric analysis of intracellular cytokine expression at the single-cell level, we analyzed helper-T (Th) and cytotoxic-T (Tc) subsets in patients with AA and MDS of refractory anemia (RA) subtype. The results showed marked increases in the Th1/Th2 ratio and Tc1/Tc2 ratio in both AA and MDS/RA. Overproduction of cytokines inhibitory to hematopoiesis reported so far might be a reflection of imbalanced development of Th and Tc. Determination of the factors that affect Th and Tc profiles may lead to further understanding of immunological states and the development of effective immunotherapy in AA as well as some types of MDS. Copyright 2000 Wiley-Liss, Inc.