PHENOTYPIC DIFFERENCES AMONG MORPHOLOGICALLY SIMILAR SMALL-CELL CARCINOMAS DETECTED WITH A PANEL OF MONOCLONAL-ANTIBODIES AND INDIRECT IMMUNOFLUORESCENCE AND FLOW-CYTOMETRY

Indirect immunofluorescence and flow cytometry were used to determine reactivity of a panel of 75 monoclonal antibodies (MAbs) and controls (provided by the Third international IASLC Workshop on Lung Tumor and Differentiation Antigens) with 3 morphologically similar prototype con tinuous-culture small-cell-carcinoma cell lines (SCC) (NCI-H69, NCI-HI 46, and NCI-H510). All cell lines had some reactivity with some of the MAbs. There is, however, differential expression of antigens amongst the prototype cell lines, which may provide a useful method for phenot yping and sub-classifying SCC. The reactivity of the 3 cell lines was greatest with MAbs in Clusters 1, 1c, 2, 4, 6, and 9, and least with M Abs in clusters W7, 8, 13, 14, and W15, with few exceptions. Although morphologically similar, each of the SCC cell lines has a unique patte rn of reactivity with the workshop MAbs. For example, although a contr ol MAb, CD56 (NKHI), which identifies an epitope on NCAM (neural cell adhesion molecule) common among many SCC lines, stained more than 90% of cells in each of the prototype cell lines, one MAb of the current p anel, SEN7, which also identifies a CD56 epitope on 15 SCC lines did n ot react as strongly with H-146 and H-510 as with H-69. If appropriate ly reactive MAbs can be identified for individual patients' tumors, th ey can be coupled to suitable radioisotopes or toxins for individualiz ed patient treatment. (C) 1994 Wiley-Liss, Inc.