[CD34+ cells in the autotransplant of bone marrow and peripheral blood].

Identification of a glycoprotein expressed on 1.2% of normal bone marrow cells, including progenitors of all hematolymphopoietic lineages and pluripotent stem cells, has allowed the production of several monoclonal antibodies directed against the same structure and included in the new differentiation cluster CD34. Availability of these antibodies coupled with techniques of positive selection of normal progenitors has opened an interesting and new alternative for purging bone marrow. Two of these techniques (avidin-biotin immunoadsorption on column and paramagnetic microspheres) have found clinical application and recently data on the first series of patients transplanted with CD34+ cells enriched marrows have been published. In the area of peripheral blood stem cells transplantation, detection by flow cytometry of CD34+ cells in the peripheral blood should replace the poorly standardized CFU-GM assay, allowing the best timing of apheretic procedures and the easy quantification of stem cells number in a harvest. Combination of negative (tumor cell killing) and positive (hemopoietic stem cell purification) selection might result in a significant improvement of the purging procedure and in a larger application of autologous hematopoietic stem cell transplantation for hematological and non-hematological malignancies.