Hyperprolactinemia in acute myeloid leukemia and indication of ectopic expression of human prolactin in blast cells of a patient of subtype M4.

The sera of 28 patients with acute myeloid leukemia AML--subtypes M1 to M6 were screened for human prolactin (h-PRL). Serum TSH (thyroid stimulating hormone), LH (luteinizing hormone), FSH (follicle stimulating hormone), beta-estradiol, free T4 (tetra-iodotyronine) and testosterone were also determined. It was found that in 16 of the 28 patients h-PRL was significantly elevated while all other endocrine values were normal. In a patient subtype M4 with elevated serum h-PRL we demonstrate by immunoblotting that the hormone and its dimer are present in the blast cells. This may reflect ectopic synthesis due to altered expression of homeobox genes and a requirement of h-PRL as a growth stimulant of the leukemic myeloblast.