Parameters Used For Measurement Of Pbsc

HSC are clonogenic cells capable of self-renewal and multilineage differentiation. Progenitor cells are oligo-lineage cells that are already more restricted in their differentiation potential and are not able to self-renew. The expression of the antigen CD34 and lineage negativity are often used as surrogate markers for HSC and progenitor cells. The percentage of CD34+ cells in PB

under steady-state conditions is about 0.06% and about 1.1% in BM.11

Other parameters used to measure the quantity of PBSC include nucleated and mononuclear cell number (MNC) and colony-forming unit granulocyte-macrophage (CFU-GM). Several studies have shown that the number of MNC count correlates poorly with engraft-ment kinetics, thus it is no longer used for PBSC enumeration. Both the CFU-GM and CD34+ assays are the two most commonly used indicators which have been shown to predict the time to engraftment. Numerous studies have shown a relationship between the dose of CD34+ cells, the concentration of CFU-GM, and the time to engraftment.1213 However, CFU-GM assays require significant laboratory skill, and methodology in different laboratories varies greatly. Therefore, quantifying CD34+ cells by flow cytometry is now the method of choice for determining graft adequacy. Moreover, the CD34+ cell count has been shown to be a good predictor for engraftment kinetics, especially for platelets.

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