IMMUNOLOCALIZATION OF INTEGRINS IN THE NORMAL LUNG AND IN PULMONARY CARCINOMAS

Cryosections of normal adult lung (n = 7) and pulmonary epithelial tum ors, including squamous (n = 8), adeno (n = 8), bronchioloalveolar (n = 5), and large cell (n = 4) carcinomas (SCC, ACC, BAC, LCC), carcinoi ds (Cd, n = 7), and neuroendocrine carcinomas (NEC) of variable grades (n = 14) were immunostained by the avidin-biotin peroxidase (ABC) met hod with monoclonal antibodies to the alpha(1-6) and alpha(v) and the beta(1-4) integrin subunits. Normal adult alveolar septae showed varia bly intense immunoreactivity for alpha(1,3,6) and beta(1), whereas rea ctions for alpha(5) and alpha, were weaker and uneven; the remaining i ntegrin subunits were not detected. Bronchial and bronchiolar epitheli um showed variably intense staining for alpha(2.3,6,v) and beta(1,4). Reactions were often, though not invariably, basally polarized. SCC, A DC, and LCC showed variably intense reactions for alpha(2.3,6,v) and b eta(1,4). Reactions were strongly and uniformly stained for alpha(2,3, 6,v) and beta(1,4). In Cd, alpha(1,2,3,v) and beta(1) reactions were n oted, whereas in NEC, weak alpha(1,3) and beta(1) staining was detecte d with only traces of alpha(6) and alpha(v). We conclude that alveolar epithelial cells do not express the hemidesmosome-associated, laminin -binding integrin alpha(6) beta(4) of the bronchial epithelium but rat her the alpha(1) beta(1) and alpha(3) beta(1), collagen IV, and lamini n receptors, respectively. SCC, ADC, and sampled LCC express an integr in repertory qualitatively similar to that of the bronchial epithelium . Distinct from the latter, the integrin repertory of BAC parallels th at of the alveolar epithelium by its strong expression of the multipot ential alpha(1) beta(1) and alpha(3) beta(1) integrins. NEC tumors do not display the laminin receptors alpha(6) beta(4) and alpha(6) beta(1 ) shown by SCC and ADC but express instead alpha(1) beta(1), a collage n IV-laminin receptor rarely found in epithelial neoplasms except for BAC. In NEC tumors, integrins, especially alpha(2), decrease with dedi fferentiation. Notably distinct from epithelial mesotheliomas, the maj or fibronectin-binding integrin alpha(5) beta(1) was not found in any type of lung carcinoma. Copyright (C) 1997 by W.B. Saunders Company.