Acute leukemias express a functional receptor for the human growth hormone

The potential influence of the human growth hormone (hGH) on the behavior of acute leukemias is a matter of controversy. We investigated primary childhood and adult leukemias (n = 44) and leukemic cell lines (n = 13) for the expression of the hGH receptor (hGHR) by immunohistochemistry and flow cytometry. All leukemias expressed the hGHR in the cytoplasm; expression on the surface was undetectable in some of the leukemias. In leukemic cell lines, hGHR expression on the surface was demonstrated in a dose-dependent manner after incubation with rhGH. Physiologic concentrations of hGH were more efficient than higher doses in increasing hGHR surface expression. A proliferative response to hGH was accomplished in cell lines REH, Molt4, and K562. However, only one of 19 primary leukemias (ALL, n = 12; AML, n = 7) showed increased cell counts after the addition of 50-800 ng/ml recombinant hGH (rhGH). These cells were of an immature T-cell phenotype. We thus conclude that acute leukemias can be stimulated by hGH to up-regulate its receptor, but that most primary leukemias may require additional signals for the induction of proliferation.