An increased traffic of hematopoietic progenitor cells (HPC) between bone marrow and peripheral organs is a peculiar feature of the allergic inflammation. It has been recently reported that the sublingual form of specific immunotherapy (SLIT) is capable of reducing such an increased HPC traffic. The House Dust Mite major antigen Der p1 has been proved to up-regulate the expression of the ICAM-1 and VCAM-1 endothelial addressins, supporting the view of an inflammatory cell recruiting at the site of allergen extract administration. In the present work we have investigated, by flow-cytometric techniques, the expression of the two major integrins CD11a (LFA-1) and CD49d (VLA-4) that are the homing receptor cognate for ICAM-1 and VCAM-1 on human cord blood CD34 hematopoietic progenitor and stem cells. Even if both the investigated molecules resulted detectable on CD34+ HPC surfaces, being the system redundant, the density of the cellular expression was significantly higher for CD49d (median value: 158) than CD11a (median value: 20.5), suggesting a preferential usage of the homing axis VLA-4/VCAM-1. Results consistency with outcomes of clinical trials that relate SLIT efficacy to allergen dosage is discussed.