HETEROGENEITY OF HUMAN LUTEINIZING-HORMONE IN PITUITARY-TUMOR HOMOGENATES AND CELL INCUBATES

Incubation media of pituitary cells and homogenates of pituitary tumor s were studied by isoelectric focusing followed by radioimmunoassay. A lmost all LH-immunoreactive components detected had been observed in e arlier studies on highly purified preparations. In one pituitary tumor homogenate, intact LH (LH(i)) was detected. The majority of LH(i)-com ponents present in this tumor were relatively acidic (LH Type I) compo nents. The corresponding beta-subunit population was in agreement with the one earlier observed for Type I LH. In all other tumor homogenate s only alpha- and beta-subunits could be detected. In incubation media of pituitary cells from patients with-no known endocrine disease nor a pituitary tumor highly acidic populations of alpha-subunits were det ected. In only one of the incubation media significant amounts of LH(i ) and free beta-subunits were observed. In an incubation medium of a T SH-producing pituitary tumor significant amounts of intact LH, free al pha- and beta-subunits were detected. The cell contents of this tumor contained components with lower pI-values than the medium. In general a good correlation is observed between the population of LH-components in material from individual identifiable pituitary glands and in high ly purified preparations from large numbers of anonymous pituitary gla nds.