Analysis of CD34-positive hemopoietic progenitor cells from normal human adult peripheral blood: flow-cytometrical studies and in-vitro colony (CFU-GM, BFU-E) assays.

Hemopoietic progenitor cells are present in minute numbers in the peripheral blood of healthy adults. By in vitro colony-assays evaluating BFU-E- and CFU-GM-growth, their numbers have been estimated to be about 1,000 per 1.0 ml of whole blood. Employing a CD34-moAb, detecting an antigen present on virtually all hemopoietic progenitor cells, and by using multiparameter flow-cytometry, we have designed a flow-cytometric method for the quantitation of CD34(+)-cells in blood. Comparative studies on bone marrow and blood have shown that CD34(+)-cells from both sources display almost identical light-scatter characteristics. They differ, however, with regard to the coexpression of the CD33- and the CD19-antigens. In vitro colony-assays for BFU-E and CFU-GM in single cultures have shown that about 25% of the CD34(+)-cells from blood were clonogenic in vitro. Our data indicate that the CD34(+)-cells from peripheral blood differ substantially from bone marrow CD34(+)-cells.