THE COEXPRESSION OF CD34-ANTIGEN OF EARLY HEMATOPOIETIC PRECURSORS AND FAS APO-1 (CD95) ANTIGEN MEDIATING APOPTOSIS/

There has been studied the expression of Fas/APO-1 antigen which media tes apoptosis, and CD34 antigen - the marker of polypotent hemopoietic stem cell - on the leucocytes from chronic myeloleukemia (CM) patient s at chronic stage of the disease, and on blast cells at the stage of blast crisis. Cells from the CM patients at the stage of blast crisis were investigated several times before each course of chemotherapy. In 3 from 8 CM patients at chronic stage CD34 antigen was expressed on 3 -7% of blood leucocytes. In patients at the stage of blast crisis CD34 antigen was found in 13 from 15 cases. The number of antigen-positive cells was 4-70% of cells. In CM patients at the stage of blast crisis Fas/APO-1 antigen was revealed on blast cell in 11 from 15 cases. The number of antigen-positive cells was 4-88%. High correlation (r=8.89) between the expression of CD34 and Fas/APO-1 antigens was shown. Sinc e CD34 antigen is a marker of polypotent hemopoietic stem cell, the re sults obtained prove that Fas/APO-1 antigen which mediates apoptosis, is also expressed on stem cell.