Influence Of Race and Ethnicity On The Collection Of G-CSF Mobilized Peripheral Blood Stem Cells From Unrelated Donors, a Center For International Blood and Marrow Transplant Research Analysis

Peripheral blood stem cell (PBSC) collection is increasingly used in allogeneic stem cell transplantation. However, a small percentage of healthy donors have a poor mobilization response to G-CSF. Very little information exists on the effect of donor race or ethnicity on PBSC mobilization. We analyzed 10776 unrelated donors from the National Marrow Donor Program (NMDP) who underwent G-CSF mobilized PBSC collection from 2006–2012. We investigated the effect of self-reported donor race/ethnicity on collection efficiency, defined as number of CD34+ cells/L (of donor blood processed), number of mononuclear cells (MNC)/L and CD34+ cells/MNC collected on the first day of apheresis. Categorical variables were analyzed by the Chi-square test and the Kruskal-Wallis test was used for continuous variables. A linear regression model was used to compare the various race/ethnic groups while controlling for potential confounding factors (such as age, BMI, gender, and year of apheresis). The result of our analysis is shown in Table 1. Univariate analysis revealed statistically significant differences in CD34+ cells/L, MNC/L and CD34+/MNC in all races analyzed. In general, African Americans (AA) had the highest collection efficiency while Caucasians had the lowest. Other races/ethnicities had collection efficiencies between the two groups. On multivariate analysis, statistically significant differences in CD34+ cell/L were seen in Hispanics, AA and Asian/Pacific Islanders (API), primarily in the obese (Hispanic, AA, API) and overweight (AA, API) donors. In the API group the differences in collection efficiency were predominately seen in males. No differences were seen between Caucasians and Native Americans. This study reveals significant racial/ethnic differences in the efficiency of collection of CD34+ cells in unrelated donors. Although these differences do not appear to interfere with the ability to collect adequate numbers of PBSC, it is currently unknown why they exist. This is an area for continued research.