Nucleated red blood cells in normal bone marrow for transplantation

Nucleated red blood cells (nRBCs) are indistinguishable from white cells, and therefore are counted by standard electronic cell counters as white cells. We sought to find a correlation between the number of nRBCs and the age of the bone marrow donor, and determine when to correct the total nucleated cell count (TNCC), when reporting graft data.

Presence of nucleated red blood cells was evaluated in 117 samples of normal bone marrow from the donors aged 3 months to 52 years. The nRBCs were counted manually on the smear of bone marrow as the numbers of nucleated RBCper 100 of white cells. The TNCC was obtained from the automated hematological counter Sysmex 9500.

The number of nRBCs was substantial in the bone marrow of older donors (up to 44 per 100 of white cells). There was significantly higher number of nRBCs in the bone marrow of older donors. There was no statistically significant difference in the number of nRBCs between female and male bone marrow. The presence ofnRBC in Hematopoietic Progenitor Cell, Marrow (HPC, Marrow) products gives a falsely high cell dose as well as a falsely high dose of total and CD34+ cells per kg, when the flow cytometric dual platform count based on International Society ol Hematotherapy and Graft Eunineering guidelines is utilized (ISHAGE).

The outcome of the bone marrow transplantation depends on the total nucleated cells dose, and the dose of CD344 cells/kg. It is therefore important to evaluate correctly the quality of the graft. We propose, that the rule of correction for nRBCs in bone marrow for transplantation should be applied if the number of nucleated red blood cells is > or = 5 per 100 of white blood cells.