African American adult apheresis donors respond to granulocyte–colony‐stimulating factor with neutrophil and progenitor cell yields comparable to those of Caucasian and Hispanic donors

Abstract

Granulocyte-colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cells (PBPCs) are the most common source of cells used for hematopoietic transplantation. Benign ethnic neutropenia has been found in persons of African descent, affecting circulating white blood cells (WBCs), but not WBC production within marrow. Persons of African descent have reduced neutrophil mobilization after steroid administration, and newborns have fewer nucleated and progenitor cells in their cord blood. Twenty-two African American (AA) and 12 Hispanic PBPC donors were age, sex, and weight matched with 34 Caucasian donors. Groups were compared based on WBC and neutrophil counts after mobilization and numbers of CD34+ cells collected on Day 5 of G-CSF mobilization. AA donors had significantly lower baseline WBC (6.1±1.1 vs. 7.1±1.7, p=0.04) and neutrophil (3.4±1.1 vs. 4.5±1.3, p=0.01) counts compared to matched Caucasian donors. G-CSF-stimulated AAs had a significantly greater increase in WBC and neutrophil counts compared to matched Caucasians (889±293% vs. 665±230% neutrophils, p=0.02). There was no significant difference in product cell counts when comparing total nucleated, CD3+, CD34+, and mononuclear cells or colony-forming units (CFUs) between Caucasians and Hispanics or AAs and trends to greater numbers of neutrophils in products from AA donors. When stimulated by G-CSF, AAs are able to increase WBC and neutrophil counts to a higher degree than Caucasians, achieving similar numbers of neutrophil and progenitor cells in apheresis products despite starting from lower baseline blood counts.