Effect of beta-endorphin and beta-endorphin-like peptide immunorphin on the growth of human leukemic cells in vitro.

The influence of beta-endorphin and immunorphin on human leukemic cell growth in vitro was studied. It was shown that both peptides increase the growth of T-lymphoblastoid cells in a dose-dependent manner. The effect of these peptides on the 3H-thymidine incorporation into T-lymphoblastoid cell line Jurkat was not reversed by the antagonist of opioid receptor naloxone. Interestingly, these peptides had no effect on B-lymphoblastoid and promyelocyte cell growth, however they enhance 3H-thymidine incorporation into myeloid cell lines.