Morphology and antigen expression profile of pulmonary neuroendocrine cells in reactive proliferations and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH).

AIMS

To compare the morphology and antigenic profile of pulmonary neuroendocrine cells (PNECs) proliferating as a reaction to pulmonary injury with those proliferating in diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) in which carcinoids develop.

METHODS AND RESULTS

The morphology and expression of a range of antigens including markers of epithelial differentiation [cytokeratins, thyroid transcription factor (TTF)-1], neuroendocrine antigens [neural cell adhesion molecule (NCAM), chromogranin, protein gene product (PGP) 9.5, neurone-specific enolase (NSE), synaptophysin], peptide products [gastrin-releasing peptide (GRP), calcitonin, calcitonin gene-related peptide (CGRP)] and inactivator [common acute lymphoblastic leukaemia antigen (CALLA)] and antigens involved in cell proliferation and death (p53, p16, p27, Rb, Bcl-2, c-kit, Ki67) were studied in four cases of reactive PNEC proliferation and seven cases of DIPNECH. Proliferation was more florid in DIPNECH. There was no major shift in antigen expression with proliferation in either group apart from CALLA, which was expressed only by proliferating cells and not by solitary PNECs. There were differences between the groups in expression of p53, p16 and Ki67, which were seen more consistently and earlier in proliferation in DIPNECH.

CONCLUSIONS

These data suggest that there are early and fundamental differences in cell kinetics between the reactive PNEC proliferation that occurs in response to pulmonary injury and that seen in the pre-neoplastic condition of DIPNECH.