Improved yield of peripheral blood progenitor cells on the Cobe Spectra

The efficiency of leucapheresis using the Cobe Spectra depends on the observation of the operator to monitor the haematocrit (Hct) in the collection line at the recommended Hct of 1%. Cells were harvested by processing 3 x total blood volume (TBV) over 3-4 h. During the harvest the manual Hct and the colony-forming units granulocyte-macrophage (CFU-GM) concentrations were analysed in the collection line in the observed Hct range of 1-7.5%. There was a correlation between the manual and observed Hct (r = 0.97). The CFU-GM concentration was normalised to allow comparison between patients. The increase was statistically significant between 1-2% (P = 0.04) and 1-3% Hct (P = 0.05). The increase in CFU-GM concentration remained at the termination of harvest, indicating that not all available CFU-GM were harvested. The optimum concentration of progenitor cells was found to be at 3% Hct. We postulate that this may permit the collection of sufficient cells on one occasion to allow PBPC autografting in the majority of patients who respond to mobilisation.