Changes in immunoreactive beta-endorphin, methionine-enkephalin and ACTH in bone marrow cells and fluid from leukemic children.

The present study demonstrates the presence of the endogenous opioid peptides, beta-endorphin (beta-EP) and methionine-enkephalin (MET-ENK), and of ACTH in cell homogenates and interstitial fluid from sternal biopsy of leukemic children. The peptides were identified by chromatography and radioimmunoassay. In leukemic children with lymphoblastic cells present in the sternal sample, concentrations of immunoreactive (ir) beta-EP in the cell homogenate, but not in the fluid, were significantly higher than in leukemic children with normal bone marrow. In contrast, ir MET-ENK and ir ACTH did not differ between the two study groups either in the cell homogenate or in the fluid. These data suggest the presence of a complex system of opioid peptides in the cells and interstitial fluid of bone marrow of leukemic children with the highest concentrations of ir beta-EP appearing in samples collected during the active phase of the disease, and may suggest a possible role of opioid peptides as immunomodulatory substances.