CONSTRUCTION OF A HIGHLY ACCURATE PREDICTION FORMULA FOR CD34⁺ CELL YIELD IN PERIPHERAL BLOOD HEMATOPOIETIC STEM CELL HARVEST

Abstract

The conventional prediction formula for CD34⁺ cell yield in peripheral blood hematopoietic stem cell harvest (PBSCH) is composed of peripheral blood CD34⁺ cell number, the processed blood volume, and body weight. In the present study, we proposed a novel prediction formula that includes the collection efficiency. The collection efficiency is defined by the following: the number of collected cells/the total number of CD34⁺cells in the processed blood. We evaluated the correlation between several factors that may affect the actual collection efficiency and the collection efficiency calculated using the above formula and the actual CD34⁺ cell number obtained by PBSCH. Among these, 32.5× (WBC/Hct) ^-0.364 showed the best correlation with collection efficiency. Therefore, we included it to represent collection efficiency in the prediction formula. These findings indicate that high WBC numbers leads to low CD34⁺ cell yield, presumably because the WBC sedimentation rate is low in the presence of high WBC numbers. Based on analysis of 48 PBSCH from 23 adult patients, the new prediction formula containing the collection efficiency showed higher prediction accuracy than the conventional prediction formula. This prediction formula allows prediction of the number of CD34⁺ cells before PBSCH and identification of the best conditions for PBSCH.