We read with interest the article “Redefining endothelial progenitor cells via clonal analysis and hematopoietic stem/progenitor cell principles” by Yoder et al.1 The authors compared 2 types of colony assays that have been shown to identify endothelial progenitor cells (EPCs)2,3 and studied the function of the cells derived from these assay systems. They found that a commercially available kit...

Hematological abnormalities have been found in the majority of patients with AIDS, in addition to immunological derangements [1]. Furthermore, treatment of opportunistic infections with folic acid antagonists and of neoplasms with cytostatic drugs is frequently complicated by profound thrombocytopenia, neutropenia, and anemia, thus resulting in the withdrawal of the drugs. In the present study ...