Assessment of bone marrow stem cell reserve and function and stromal cell function in patients with autoimmune cytopenias.

To investigate whether bone marrow (BM) stem cell compartment and/or BM microenvironment are affected by the immune insult in autoimmune cytopenias (AICs), BM stem cell reserve and function and BM stromal function were studied in 15 AIC patients. Stem cells were evaluated by means of flow cytometry, clonogenic progenitor cell assays, long-term BM cultures (LTBMCs), and limiting dilution assay for quantification of long-term-culture initiating cells (LTC-ICs). Stromal cell function was assessed with the use of preformed irradiated LTBMCs from patients and normal controls, recharged with normal CD34(+) cells. AIC patients exhibited a high number of CD34(+), CD34(+)/CD38(+), and CD34(+)/CD38(-) cells; high frequency of granulocyte-macrophage colony forming units in the BM mononuclear cell fraction; high colony recovery in LTBMCs; and normal LTC-IC frequency. Patient BM stromal layers displayed normal hematopoietic-supporting capacity and increased production of granulocyte-colony stimulating factor. Data from this study support the concept that AIC patients with severe, resistant disease might be appropriate candidates for autologous stem cell transplantation.