Heterogeneity of human luteinizing hormone in pituitary tumor homogenates and cell incubates.

Incubation media of pituitary cells and homogenates of pituitary tumors were studied by isoelectric focusing followed by radioimmunoassay. Almost all LH-immunoreactive components detected had been observed in earlier studies on highly purified preparations. In one pituitary tumor homogenate, intact LH (LHi) was detected. The majority of LHi-components present in this tumor were relatively acidic (LH Type I) components. The corresponding beta-subunit population was in agreement with the one earlier observed for Type I LH. In all other tumor homogenates 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 detected. In only one of the incubation media significant amounts of LHi and free beta-subunits were observed. In an incubation medium of a TSH-producing pituitary tumor significant amounts of intact LH, free alpha- and beta-subunits were detected. The cell contents of this tumor contained components with lower pl-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 highly purified preparations from large numbers of anonymous pituitary glands.