Immunohistochemical Identification of Exocrine and Neuroendocrine Subsets of Large Cell Lung Carcinomas

Immunohistochemical Analysis of Human Adenocarcinomas of the Lung Using the Monoclonal Antibody 44–3A6

“…There was some variability, however, in the intensity of the staining from cell to cell. Nonneoplastic bronchial and bronchiolar epithelia, especially basal cells, and type II pneumocytes were positively immuno stained by MAb 44-3A6, as had been pre viously reported [36,37,39], These cell types served as internal controls, providing evidence that the tissue was adequately fixed and embedded. In total, 25 of the 39 tumors examined showed positive immuno reactivity; these results are outlined in ta ble 1.…”

“…MAbs which detect their respective antigens in routine formalin-fixed, paraffin-embedded tissues have the advantage of allowing the correlation of the histological and cytologi cal features with their immunophenotypic characteristics. We have previously reported on an MAb (44-3A6) which recognizes an antigen in formalin-fixed, paraffin-embed ded tissues and which has been shown to be associated with glandular differentiation in ACs [35], The restricted expression of the epitope recognized by MAb 44-3A6 in pri mary carcinomas of the lung has been re ported elsewhere, as well as its utility in dis tinguishing various histological subgroups of pulmonary neoplasms [36,37], It has also been shown to be of value in distinguishing mesotheliomas from ACs metastatic to the pleura, as well as in the cytological evalua tion of pulmonary neoplasms [38,39]. The MAb 44-3A6 recognizes a 40-kilodalton cell surface protein which has limited expression in neoplastic and nonneoplastic tissues [35,[40][41][42],…”

Expression of the Epitope Recognized by the Monoclonal Antibody 44–3A6 during Human Fetal Development

“…In a study of this sub group of pulmonary neoplasms, we con firmed that the expression of this antigen is frequently seen in these tumors, and that there is a very good correlation with the expression of this antigen and those large cell carcinomas which also express exocrine fea tures. This suggests a relationship between antigen expression and the expression of exocrine differentiation, despite the absence of conventional light microscopic and histo logical features seen in adenocarcinomas such as glands, papillae, or mucus [12], The expression of this antigen in normal fetal and adult tissues lacking exocrine features is therefore not surprising and supports the thought that in addition to exocrine expres sion, calcium may also regulate its expres sion.…”

“…Previous immunohistochemical studies of tumors arising in human breast and lung tissue have demonstrated that select histo logical subtypes of these tumors express de tectable levels of this antigen, and that their corresponding normal adult tissues have a more restricted pattern of expression [10], Within pulmonary neoplasms, which have been extensively studied, adenocarcinomas frequently express this antigen, as well as other select subtypes [11][12][13][14], Among those subtypes which express this antigen are the large cell carcinomas. In a study of this sub group of pulmonary neoplasms, we con firmed that the expression of this antigen is frequently seen in these tumors, and that there is a very good correlation with the expression of this antigen and those large cell carcinomas which also express exocrine fea tures.…”

Changes in the Expression of the Tumor-Associated Antigen Recognized by Monoclonal Antibody 44–3A6 in A549 Cells due to Calcium

“…The human lung adenocarcinoma cell line was grown in RPMI 1640 culture medium supplemented with 10%fetalcalf serum, L-glutamine, and antibioticantimycotic solution as previously reported [9]. The RPMI 1640, besides other ingredients, contains 0.5 mM calcium.…”