A comparison was made of the cytokine transcripts in normal, monoclonal, MDS, and AML marrow aspirates. While both normal and monoclonal marrow aspirates contain transcripts for SCF, few MDS or AML marrow aspirates contain these transcripts. Similarly, IL1ra transcripts are found with reduced frequency in MDS and AML marrow aspirates. The fall in SCF transcripts between monoclonal and MDS marrow aspirates parallels the appearance of apoptosis and the reduced in vitro proliferative ability which are characteristics of MDS marrow aspirate cells. The frequent IL1beta production by MDS and AML marrow aspirate cells, with few marrow aspirates producing IL1ra transcripts, suggests that unbalanced IL1beta effects may contribute to the proliferative advantage of MDS and AML cells over their normal counterparts.