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gence of an abnormal giant-cell population, and the progressive clonogenic cell loss that occurred after treatment was thought to be due to oxygen and nutrient deprivation of the remaining viable cells by this doomed cell population. Correction of the growth delay measurements for changes in cell size and clonogenic cell population allowed correlation of the growth delay and cell survival data.

A Comparison of Clonogenic and Radionuclide Uptake Assays for Deter- mining the Radiation Response of Human Small-Cell Lung Cancer Xenografts and Cell Lines. Fox, N.E., Twentyman, P.R. Medical Re- search Council Clinical Oncology and Radiotherapeutics Unit, MRC Centre, Cambridge CB2 2QH, U.K. Br. J. Radiol. 60: 381-388, 1987.

Previous work has suggested that a radionuclide (3HTdR) uptake assay can provide a measure of drug and radiation sensitivity comparable with that given by the clonogenic assay. We have now extended this work to examine the radiation response of human small-cell lung cancer xenografts and cell lines with a wide range of plating efficiencies. Preliminary experiments using cultured cells indicated that ir- radiation of a single-cell suspension following disaggregation generally produced similar response data to those obtained when cultures were irradiated in situ and subsequently disaggregated. The response of eight cell lines to a single dose of 2 Gy was measured using both radionuclide uptake and clonogenic assays. There was no correlation be- tween the two sets of data. Agreement between the radiation-response curves obtained using 3HTdR uptake and clonogenic assays was better for high plating efficiency xenografts (NCI-H69, COR-L51) than for low plating ef- ficiency xenografts (COR-L24, COR-L31). Radionuclide uptake indicated very shallow response curves for the low plating efficiency lines. Altering the time of radi~,nuclide addition from the standard Day 4 to other times between Day 2 and Day 6 did not greatly change the indications of radioresponsiveness provided by the assay. Growth-curve ex- periments for line COR-L24 showed that cell numbers at Day 4 after irradiation with 1.5 Gy or 3 Gy were very similar to those in unirradiated cultures. For NCI-H69, however, the cell numbers were very different for the different radia- tion doses. It appears that a high proportion of cells in lines such as COR-L24 take many days to show radia- tion damage as measured by reduced 3HTdR uptake.

Isolation of Small Cell Lung Cancer- Associated Antigen From Human Brain. Watanabe, J.-I., Okabe, T., Fujisawa, M. et al. The Third Department of In- ternal Medicine, Faculty of Medicine, University of Tokyo, Tokyo 113, Japan. Cancer Res. 47: 960-962, 1987.

Previous studies have demonstrated that monoclonal antibody TFS-4 recog- nizes a cell surface antigen with a molecular weight of 124,000 expressed selectively on small-cell lung cancer but not on non-small-cell lung cancers and that is cross-reacts with human brain. The antigenic determinant on small-cell lung cancer and that on brain shared common characteristics, i.e., trypsin sensitivity, heat lability, and neuraminidase resistance, suggesting that they are similar pep- tides (T. Okabe et al., Cancer Res., 44: 5273-5278, 1984; J-i. Watanabe et al., Cancer Res., 47: 826-829, 1987). In order to elucidate the nature of this unique antigen recognized by TFS- 4, we have purified the antigen to homogeneity from human brain. The an- tigen was solubilized from brain with 0.5% Nonidet P-40, precipitated with 50% ammonium sulfate, and subsequently purified by sequential chromatographi- es, i.e., diethylaminoehtyl-Sepharose ion exchange, immunoaffinity, and gel permeation high-pressure liquid chromatography. The antigenic reac- tivity was assessed by immunoblotting using TFS-4 as a primary antibody. The purified antigen showed a single protein band with a molecular weight of 124,000 on sodium dodecylsulfate- polyacrylamide gel electrophoresis detected by a silver staining technique. The results suggest that the antigen on brain tissues is struc- turally related to the molecule expressed on small-cell lung cancer.

Monoclonal Antibody that Distinguishes Small-Cell Lung Cancer From Non-Small- Cell Lung Cancer. Watanabe, J.-I., Okabe, T., Fujisawa, M. et al. The Third Department of In- ternal Medicine, Faculty of Medicine, University of Tokyo, Hongo, Tokyo 113, Japan. Cancer Res. 47: 826-829, 1987.

To examine whether a monoclonal antibody, TFS-4, can distinguish small- cell lung cancer from non-small-cell lung cancers, an extensive survey of fresh lung tumors, cancers from other organs, and normal tissue specimens has been carried out. The antibody has been shown to react specifically with small- cell lung cancer (15 of 15) but not with squamous cell carcinoma (0 of 20), adenocarcinoma (0 of 20) of the lung, or large-cell lung cancer (0 of 2). It reacted neither with other malignancies, including colorectal cancer, gastric cancer, and malignant

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lymphoma, nor with such normal tissues as trachea, lung, liver, pancreas, colon, kidney, spleen, skin, striated muscle, bone marrow, or peripheral blood cells. Interestingly, the an- tibody cross-reacted with central nerv- ous tissues. The antigenic determinant on small-cell lung cancer and that on human brain were both heat labile and trypsin sensitive, but resisted treat- ment with neuraminidase, suggesting that they represent similar peptides. TFS-4 may be of clinical use in the diagnosis of small-cell lung cancer, while the antigen may help investigate the nature and origin of small-cell lung cancer.

Distribution of Lung Adenocarcinoma- Associated Antigens in Human Tissues and Sera Defined by Monoclonal An- tibodies KM-52 and KM-93. Shitara, K., Hanai, N., Yoshida, H. Tokyo Research Laboratories, Kyowa Hakko Kogyo Co., Ltd., Machida-shi, Tokyo, 194 Japan. Cancer Res. 47: 1267- 1272, 1987.

Two monoclonal antibodies to human lung adenocarcionma, KM-52 and KM-93, were generated by the novel immunizing procedure using mice rendered tolerant to the normal human lung. KM-93 recog- nized sialylated carbohydrate epitope on the antigen different from CA19-9 and DU-PAN-2, while KM-52 recognized the protein antigen. Both antigens were different from carcinoembryonic antigen, alpha-fetoprotein, and beta-2- microglobulin. Distribution of KA-52 and KA-93, the antigens recognized by KM-52 and KM-93, respectively, in various tissues and sera was investigated. In immunoperoxidase staining, KM-93 reacted strongly and frequently with tumor cells of lung adenocarcinoma and partially with those of lung sguamous cell carcinoma, large cell carcinoma, and small cell carcinoma. In normal adult and fetal tissues, KA-93 was expressed on the surface of a small number of cells of the lung, pancreas, liver, kidney, and bone marrow. KM-52 reacted selectively with tumor cells of adenocarcinoma among four different histological types of lung carcinoma. In normal adult and fetal tissues, KA-52 was distributed on a small number of cells of the lung, stomach, intestine, and pancreas. Of the two monoclonal antibodies, KM-93 could be used in detecting the antigen in sera of patients with lung cancer. The KA-93 level in sera was determined by the sandwich-type enzyme-linked im- munosorbent assay. Serum with a high KA-93 level was found in 34 of 70 patients with lung adenocarcinoma (48.6%), one of 67 healthy adults (1.5%), and none of 32 patients with benign diseases (0%). Combined detec-

tion by KA-93 with KA-32, a new tumor marker of lung squamous cell carcinoma, elevated the positive percentage in patients with lung squamous cell car- cionma (52.7%) and with lung adenocar- cinoma (59.5%). These results suggested that KM-52 and KM-93 would be potential monoclonal antibodies in immunohis- tological diagnosis and serum diagnosis of lung adenocarcinoma, respectively.

Glycoproteins Distinguishing Non-Small Cell From Small Cell Human Lung Car- cinoma Recognized by Monoclonal An- tibody 43-9F. Pettijohn, D.E., Stranahan, P.L., Due, C. et al. Cancer Biology Laboratory, State University Hospital (Rigshospitalet), Copenhagen, Denmark. Cancer Res. 47: 1161-1169, 1987.

Cell lines derived from human squamous lung carcinoma release large amounts of a soluble glycoprotein into the culture media, having very high molecular weight (> 2 x 106 ) and mucin- like properties. A monoclonal antibody called 43-9F has been generated that recognizes a carbohydrate epitope on the glycoconjugate. The epitope is also present on a diverse set of smaller glycoproteins (M(r) 50,000-200,000) distributed primarily on the surface of the squamous lung carcinoma cells. A sensitive assay using the 43-9F an- tibody in a dot blot procedure has been devised that is able to detect an amount of antigen less than that possessed by a single squamous lung carcinoma cell. This assay, and also conventioanl immunofluorescence and im- munohistochemical assay procedures, have been used to screen different nor- mal cells, normal tissues, cancer cells, and tumor biopsy specimens for the antigen. In the normal lung the 43- 9F antigen is found only on cells of some of the seromucous glands. In the normal digestive system it is as- sociated in certain organs only with a limited population of mucosal epithelial cells. Other organ systems lack any reactive cells. The cells of most human non-small cell lung car- cinomas and their released glycocon- jugates have large amounts of the 43-9F epitope, while small cell lung car- cinomas and the glycoconjugates released by small cell lung cancer cells lack the epitope. The oligosac- charide recognized by the 43-9F an- tibody may therefore provide a useful marker to distinguish the different lung carcinomas and for investigating the different cells of origin of these tumors.

Selective Stimulation of Small Cell Lung Cancer Clonal Growth by Bombesin and Gastrin-Releasing Peptide. Carney, D.N., Cuttitta, F., Moody,