The CD34 antigen: potential clinical advantages of CD34 selection.

The availability of monoclonal antibodies directed towards the haemopoietic cell surface antigen CD34 has facilitated accurate measurement, by flow cytometry, of CD34 positive cell frequencies in bone marrow and peripheral blood. In addition, a range of CD34 selection techniques, to purify peripheral blood progenitor cells or bone marrow prior to transplantation, have been developed. CD34 positive stem and progenitor cells may be selected with final purities in excess of 90%. Such pure populations of CD34 positive stem cells may be useful in several clinical areas, including tumour cell purging and T-cell depletion, and as a basis for gene therapy and stem cell expansion.