Morphologic, immunophenotypic and in vitro growth characteristics of bloodand bone marrow associated with stem cell mobilisation in patients with lymphoma

The proportion of CD34+ cells in the bone marrow (BM) is predictive of the size of progenitor cell mobilisation into the blood (PB). To investigate wh ich other PB and BM parameters may be related to mobilisation, we analysed at steady state PB and BM of 23 patients with relapsed or resistant lymphom a before administering high-dose cyclophosphamide and G-CSF Cell morphology , number of CD34+ cells, and growth in clonogenic assay and in long- term c ultures (LTC) were determined and then correlated with mobilisation extent (CD34+ and GM-CFC) and quality (growth of harvested cells in LTC). We found that the good mobilising patients (CD34 > 50 x 10(3)/ml, n=10) had several baseline BM characteristics (number of CD34+ MNC, GM-CFC, BFU-E, productio n of CFCs in LTC) similar to a group of 12 healthy controls, while patients with reduced mobilisation (CD34 < 50 x 10(3)/ml, n=13) had clearly reduced BM progenitors and LTC growth (p < 0.05). In a multivariate analysis inclu ding baseline clinical, blood and bone marrow characteristics, the most sig nificant PB and BM factors independently associated with a higher number an d/or quality of mobilised cells were a higher number of CD34+ and GM-CFC in the BM and a higher baseline haemoglobin, platelet, and CD34+ blood count. The capacity to release progenitor cells into the circulation is therefore not predicted by the distribution of morphologically distinguishable cells , marginally predicted by the BM content of highly undifferentiated cells ( growth in long term culture), while it is proportional to the number of BM progenitors (CD34+, GM-CFC and BFU-E).