Preparation Of Anti-human Lung Cancer Monoclonal Antibodies And Radioimmunoimaging Of The Lung Cancer

Balb/C mice were immunized with giant cells of human lung cancer (PLA-801). Positive hybridoma cells were developed by fusing immunized splenic lymphocytes with Sp2/0 myeloma cells and, then, were given intraperitoneally to Balb/C mice to produce monoclonal antibodies (McAbs), 2E3 and 6D1. The subclasses of 2E3 and 6D1 were IgG1 and IgG2a, respectively. The antigens reacting with 2E3 and 6D1 were equivalent to molecular weights of 67 kd and 30 kd, respectively. Reactivity of the 2 McAbs to cancer cell lines derived from lung giant cell carcinoma, lung adenocarcinoma, lung squamous carcinoma and non-lung cancers was investigated by cell immunochemistry technique. 2E3 and 6D1 antibodies were strongly reactive with 3 lines of lung cancer cells and weakly or not reactive with non-lung cancer cells. The result of immunohistochemistry was similar to that of cell immunochemistry. McAbs reacted with all of lung cancers and part of cancers from breast and colon, and not with hepatic and gastric carcinomas.Purified McAbs were radioiodinated by chloramine T or Iodogen. The labeling yields were 54-74% with specific activities of 6-10 μCi/μg of protein. The affinity constantsof 2E3 and 6D1 determined by Scatchard analysis were 1.95 x10⁹M^-1 and 2.18 × 10⁹ M^-1 , respectively. The immunoreactivefractions of 2E3 and 6D1 estimated by the method of Lindmo were 0.52 and 0.49, respectively. The binding ratios of ¹²⁵I-McAbs with 2 lines of lung cancer cells were 24-36% and the non-specific binding with other cancer cells was less than 5.0%.The nude mice bearing human lung cancer xenografts wereeach injected intraperitoneally with 15μCi of ¹²⁵I-McAbs.The highest radioactivity was observed in tumor at 3-5 days after injection with 7.57% of whole body dose at Day 5. T/NT ratios in all normal organs and tissues were between 2 to 10 at 3-5 days after injection. The mixture of ¹³¹I-McAb and...