Identification of proliferating human anterior pituitary adenoma cells in vitro

A method to determine whether dispersed human anterior pituitary adenoma cells proliferate in mixed culture was developed. Fifteen pituitary adenomas were dispersed enzymatically to single cells, following which twelve were double immunostained after eight days. Proliferating cells were identified immunologically following one hour of bromo-deoxyuridine incorporation. Adenoma cells were subsequently identified with an anti-neuron-specific enolase antibody system. A time course of bromo-deoxyuridine labelling was performed on three nonfunctional adenomas over a four day period, with bromo-deoxyuridine being added to cultures at one hour, 24 hours and four days prior to immunostaining. Double immunolabelled cells were unambiguously identified by a dark brown nucleus surrounded by red cytoplasm. Eight out of 12 pituitary adenomas (two prolactinomas, three nonfunctional, three growth hormone secreting) showed an increased bromo-deoxyuridine labelling index (range 0.1%-1.4%). Bromo-deoxyuridine incorporation over four days showed an increase in bromo-deoxyuridine from 0.02%, 0.03% and 3.3% at one hour to 10.1%, 1.3% and 5.0% at four days, respectively, but evidence of mitosis was scant. This study shows that pituitary adenomas may proliferate in vitro and that this double immunostaining method may be used as an in vitro proliferation assay in a mixed cell population.