“…Second, leukemic lymphoblasts themselves may produce Eo-CSA. Such a mechanism has been suggested to operate partic ularly in patients with 5q and 14q cytogenetic abnormal ities, which are so common in ALL with eosinophilia [1,6,7]. Third, leukemic lymphoblasts and eosinophils may originate from a common multipotential stem cell [8,9], In the present case, the scrum obtained at the onset of ALL contained a significant amount of Eo-CSA, and T cells obtained at remission produced an increased amount of Eo-CSA with IL-2 stimulation, while leukemic cells pro duced no detectable Eo-CSA, either with or without IL-2 stimulation.…”