SELP and Chronic Eosinophilic Leukemia, Not Otherwise Specified: As the leukocyte adhesion cascade is generally considered to start with the selectins [27] and E-selectin is part of a HSC niche which might be a potential LSC niche as well [26], we chose to use a recently established xenograft model of human CEL [28] to investigate the behavior of CEL and CML cells in E- and P-selectin deficient scid mice.