IMMUNOGOLD EM LOCALIZATION OF NEUROCHEMICALS IN HUMAN PULMONARY NEUROENDOCRINE CELLS

Antibodies against the pulmonary neuroendocrine cell peptides gastrin- releasing peptide (bombesin), calcitonin and calcitonin gene-related p eptide (CGRP) have been labeled with colloidal gold spheres for immuno cytochemical localization in human fetal and newborn lung tissue. In g eneral, the presence and amount of immunolabeling increased with incre asing gestational age, with only calcitonin appearing late in fetal li fe. The largest percentage of neuroepithelial body (NEB) cells labeled and the largest number of labeled dense core vesicles (DCV) were in i nfants with chronic lung disease (bronchopulmonary dysplasia). Serial ribbons allowed identification of more than one peptide in a single NE B cell. The use of two antibodies labeled with colloidal gold spheres of different sizes allowed the identification of two peptides in the s ame DCV. Quantification of relative amounts of labeled peptides was no t possible, as the peptide labeling with the larger size gold sphere w as consistently underestimated. Colocalization to the same DCV has bee n shown in humans for bombesin and calcitonin, calcitonin and CORP, bo mbesin and CORP and, by others, for cholecystokinin (CCK) and serotoni n. Colocalization of two or more peptides or an amine to a single DCV within the same cell implies simultaneous discharge by exocytosis. The action of the two (or more) substances might be in concert, perhaps w ith one acting in a paracrine fashion, and the second in an autocrine fashion. In this case, the second peptide or amine might have a regula tory function on the parent cell, influencing DCV storage or rate of r elease. (C) 1997 Wiley-Liss, Inc.