Summary:been strengthened by several observations showing that growth factors (such as G-CSF, GM-CSF, IL-3 and SCF) modulate the expression or function of several cytoadhesive Transplantation of growth factor-mobilized peripheral blood progenitor cells (PBPC) is widely used in the molecules on the surface of hematopoietic progenitor cells. 8,9 In addition, cytokines produce profound morphotreatment of several neoplastic diseases. While in PBPC harvests the presence of several accessory immune and logical and immunohistochemical changes in marrow stroma and in the contiguous extracellular matrix. 10,11 tumor cells has been documented, that of stromal cells has not been reported. In the present study, we investiThese results suggest that marrow stroma should not be impervious to the effect of growth factors during PBPC gated for the presence of stromal cells in growth factormobilized PBPC harvests from breast cancer patients.mobilization procedures and raise the question of whether stromal cells are released from the marrow and conseLow-density cells from PBCP harvests in culture gave rise to an adherent layer containing fibroblast-like and quently are present in cytokine-mobilized PBPC harvests.In the present study, we monitored the presence of stromal large flat round cells. These cells express positive immunofluorescence staining for collagen I, collagen III, fibcells in growth factor-mobilized PBPC harvests from breast cancer patients. For this purpose, we used a two-step proronectin, VCAM-1 (CD106), ICAM-1 (CD54) and mesenchymal antigens recognized by monoclonal cedure which includes: (1)