ANALYSIS OF SURFACE-PROTEINS OF MOUSE LUNG CARCINOMAS USING MONOCLONAL-ANTIBODIES

Abstract

Hybridoma cultures secreting monoclonal antibodies were derived from fusions of parent myeloma P3-X63-Ag8 with spleen cells of F344 rats which had been immunized with the BALB/c alveolar lung carcinoma line 1. Screening of several thousand hybridoma cultures identified 55 cell lines making antibody that bound to the line 1 cell surface. Of 15 of these antibodies tested, 7 could be identified as binding to P100, a surface protein expressed on normal and tumor cells, and 5 reacted with a tumor surface protein with a MW of 180,000 (TSP-180) not found on control cell lines. Monoclonal antibodies to TSP-180 bound to lung tumor cells but not to normal cells or tumors of other organs. Five different hybridoma cultures secreting antibody to TSP-180 were cloned and monoclonal antibodies were purified by affinity chromatography. Radioiodinated monoclonal antibodies were used to determine affinity constants for binding to TSP-180 as it is expressed on 4 different mouse lung tumors. Binding constants ranged from 1.2 .times. 107 to 1.5 .times. 108 l/mol for the different antibodies.