The hematopoietic progenitors are a pool of cells which share the expression of a membrane glycoprotein: CD34. These cells are present in low frequencies in umbilical cord blood, adult peripheral blood and bone marrow (respectively, 0.1-0.6%, 0.01-0.1% and 0.8-4% of nucleated cells). The suitability of high-affinity monoclonal antibodies against the CD34 molecule, the necessity of rapid, sterile isolation methods and the chance of CD34-negative cell tumor purging in autologous stem cell

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... ntation or T-cell depletion in allogeneic transplantation has favoured a rapid development of different technical approaches for CD34+ cell selection. We can distinguish two different approaches to the CD34+ cell selection techniques: a) immunomagnetic which include a direct or indirect linkage between CD34+ cells and immunomagnetic particles, and b) immunoadsorption of CD34+ cells to an antibody-precoated plastic or avidinized poliacrilamide surfaces. All these techniques achieve variable yields between 30-70% and median purities ranging from 50-95%. An approach to the positive selection of CD34+ cells by two different indirect immunomagnetic methods is given.