Monoclonal antibodies that demonstrate specificity -for several

Transcription

1 Proc. Natl Acad. Sci. USA Vol. 78, No. 7, pp , July 1981 Medical Sciences Monoclonal antibodies that demonstrate specificity -for several types of human lung cancer (small cell lung cancer/neuroblastoma/breast cancer/lung cancer antigens) FRANK CUTTITTA, STEVEN ROSEN, ADI F. GAZDAR, AND JOHN D. MINNA* NCI-VA Medical Oncology Branch, Division of Cancer Treatment, National Cancer Institute and the Washington Veterans Administration Medical Center, Washington, D.C Communicated by Donald S. Fredrickson, April 8, 1981 ABSTRACT Monoclonal antibodies with selectivity for human lung cancer were produced by immunizing BALB/c mice with an established line of human small cell lung cancer (NCI-H69) and fusing the mouse spleen cells to mouse myeloma line X63-Ag The resulting hybrid cells were initially screened' by immunoautoradiography for production of antibodies that would react with NCI-H69 and another small cell lung cancer line (NCI-H128) but not its autologous B-lymphoblastoid line (NCI-H128BL). Stable monoclonal antibody-producing lines were isolated by repeated cloning. Three independently derived monoclonal antibodies, designated 525A5, 534F8, and 538F12, were found to react with three of the major types of human lung cancer (small cell, adenocarcinoma, and squamous carcinoma). They did not react with bronchioloalveolar and large cell lung cancers, myeloma, lymphomas, leukemias, osteogeneic sarcoma, mesothelioma, hypernephroma, malignant melanoma, simian virus 4-transformed human fetal lung cells, skin fibroblast lines, human B-lymphoblastoid lines, human erythrocytes, and rodent cells. Interestingly, these antibodies also bound to three out ofthree human neuroblastomas and two out of three breast cancers but failed to react with mouse neuroblastoma and rat pheochromocytoma. The monoclonal antibodies reacted with human small cell lung cancer tumors obtained at autopsy, but had insignificant reactions with normal human lung, liver, spleen, and skeletal muscle. We conclude that monoclonal antibodies have been generated that react with common antigenic determinants expressed on several human lung cancer types, neuroblastoma, and some breast cancers, but are not detectable by our current assays on a variety of other human tumors or normal adult human tissues. Such antibodies are of potential clinical and biological importance. Antibodies with sufficient specificity for human lung cancer are potentially important diagnostic and therapeutic tools. Several groups have prepared polyclonal antibodies with potential specificity for lung cancer by using standard immunologic methods (1-8). The development of somatic cell hybrid technology for the production of monoclonal antibodies (9) offers a different approach, and several monoclonal antibodies have been reported with various degrees of specificity to a variety of human neoplasms (1-17). In this report, we describe the use of this technology to prepare antibodies with specificity for human lung cancer. As a first approach, we wanted to make monoclonal antibodies that react selectively with lung tumors but not with autologous histocompatibility antigens. Thus, we immunized mice with a line of small cell lung cancer () and screened the resultant hybrid cell antibodies for reactivity against the immunizing line and another line and for lack ofreactivity with an autologous B-lymphoblastoid cell line. Using this strategy, we have isolated, cloned, and developed stable hybrid cell The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C solely to indicate this fact lines producing antibodies that detect determinants expressed on human, and to a lesser extent on adenocarcinomas and squamous cell carcinomas of the lung, but not on a variety of normal tissue or human cell lines. Interestingly, these determinants are also found on human neuroblastoma and breast cancer cell lines. MATERIALS AND METHODS Cells. The sources or references for the various cell lines used are shown in Table 1, and they were grown as previously reported (18) in RPMI 164 medium or Dulbecco's modified Eagle's medium supplemented with 1% heat-inactivated fetal calf serum (all reagents from GIBCO). All human lines exhibited human enzymes by starch gel electrophoresis (21). All human tumor cell lines, established in our laboratory, were from patients with documented histology of the stated tumor type, and all induced nude mouse heterotransplants with a histology similar to that seen in the patients' tumors. In addition, cell lines had typical cytology, suspension culture appearance, and high levels of L-dopa decarboxylase (EC ) (18). Human cultures that transformed to large cell cytology came from a patient whose tumor had mixtures of and large cell histology (line NCI-H82) or occurred spontaneously during long-term tissue culture (line NCI-N231/417). These transformants had reduced levels of L-dopa decarboxylase or no enzyme at all (22). The B-lymphoblastoid lines were prepared and characterized as described (23), and those from patients grew out spontaneously, from pleural fluid or bone marrow. Production, Screening, and Cloning ofhybrid Cells. BALB/ c mice were hyperimmunized with six weekly injections (2 X 17 cells per dose) of live NCI-H69 cells, with the initial immunization in complete Freund's adjuvant subcutaneously, and the next four challenges injected intraperitoneally, and the last injected intravenously 3 days before fusion. Fusions were performed according to the polyethylene glycol (PEG 1, Baker) procedure of Galfre et al. (24), using X63-Ag8.653 cells, a nonimmunoglobulin-producing mouse myeloma cell line (25). Hybrid cells were selected and grown in a modification ofkennett's formula (26) in eight 96-well microtiter plates per mouse spleen (Costar, Cambridge, MA) at 1 x 15 cells per well. Wells were screened for antibody production by immunoautoradiography 14 days after the fusion. Cultures giving positive signals with but not with autologous B-lymphoblastoid lines were "minicloned" (27), using a mouse spleen cell feeder layer. This Abbreviations:, human small cell lung cancer; PINaCl, phosphate-buffered saline; GAM, affinity-purified goat antibodies to mouse immunoglobulin Fab fragment; SAM, affinity-purified sheep antibodies to mouse immunoglobulin Fab fragment. * To whom reprint requests should be addressed.

2 4592 Medical Sciences: Cuttitta et al. Table 1. Binding of monoclonal antibodies 525A5, 534F8, and 538F12 to human lung cancer cell lines Human target cells Ref. or source * 525A5 534F8 538F12 NCI-H NCI-H NCI-H NCI-H187 This laboratory NCI-H29 This laboratory NCI-H NCI-H NCI-H to large cell converters NCI-H82 This laboratory NCI-N231/417 This laboratory Adenocarcinoma of the lung NCI-H125t This laboratory NCI-H23 This laboratory Large cell lung cancer NCI-H157 This laboratory t <.1 Squamous cell lung cancer U1752 J. Ponten, Uppsala, Sweden Adenocarcinoma lung (? bronchioloalveolar) A Assays were performed in quadruplicate, using rabbit anti-mouse IgM, and the 1 I-protein A assay, with monoclonal antibodies from ascites fluids tested at a dilution of 1:14. * = (cpm test well - cpm negative control). cpm negative control to. allow comparison between assays. Results are the average of quadruplicate determinations (less than 2% variance between wells for any one test). The negative control (within the range of 1-3 cpm. for all cell lines tested) was obtained by omitting the monoclonal antibody and substituting PIlNaCl or mouse myeloma IgM A (MOPC-14E, Litton Bionetics, Rockville, MD) in the reaction. t NCI-H125 is a malignant pleuropulmonary neoplasm compatible morphologically with adenocarcinoma or mesothelioma. * The tumor type of 9812 has been variously referred to as lung cancer and melanoma. Histologically the nude mouse heterotransplant is a large cell undifferentiated tumor compatible with either type. procedure was repeated a total of five times, until every well gave a positive reaction on cell lines but not on B-lymphoblastoid cell lines. Hybrid cells were then cloned by plating less than one cell per well, and wells with isolated colonies were identified 5 days later. Every well with a hybrid cell clone (approximately 3% of wells seeded) gave a positive signal for antibody production. Ascites fluids containing high-titered monoclonal antibody were produced by injecting hybrid cells (1Lx 17 cells) intraperitoneally into BALB/c mice primed with pristane (Aldrich) (28). Immunoassays. Affinity-purified sheep anti-mouse immunoglobulin (SAM; Cappel Laboratories, Cochranville, PA) and goat antirmouse immunoglobulin (GAM; T. Chused, National Cancer Institute), both ofwhich are directed against the mouse immunoglobulin Fab region, and purified staphylococcal protein A (Pharmacia) were labeled with '"I (Amersham) by the chloramine-t method (29) to specific activities of 14, 16, and 27 uci/4g ofprotein, respectively (1 Ci = 3.7 x 11 becquerels). Test cells (1 or 2 x 15) were washed and added to each well of a 96-well polyvinyl chloride flat-bottom microtiter plate (Cooke Industries, Alexandria, VA) or, for some of the adherent. cell lines, grown in tissue culture microtiter plates (Costar) andwashed. The cells were fixed to the wells with.25% glutaraldehyde in phosphate-buffered saline (PJNaCl) after centrif- ugation ofthe plate. The plates were washed, and the wells were coated with 1% bovine serum albumin (albumin) in PJNaCl and then stored in PJNaCl/1% albumin with.2% NaN3 at 4TC. Culture fluid supernatants or ascites fluids diluted.in PJNaCl/ 1% albumin were added to each well, incubated for 1 hr, washed, incubated with "2I-labeled GAM (125I-GAM) or labeled SAM (125I-SAM) (4,-5, cpm per well) or with rabbit anti-mouse IgM (1:15 dilution; Miles) (for known IgM monoclonal antibodies), incubated for another hour, washed, and, in the case ofplates incubated with rabbit anti-mouse IgM, incubated for a third hour with '4I-labeled protein A ('"I-protein A; 7, cpm per well) (24), washed eight times, and dried. For screening assays the plates were autoradiographed for 16 hr at -7TC, with Kodak XR-5 film and a Du Pont Lightningplus intensifying screen. For quantitation, the polyvinyl wells were cut out with a hot wire device, or the contents of the wells from tissue culture assay plates were solubilized in 1% sodium dodecyl sulfate and their radioactivities were measured in a gamma counter. Amplification of 5- to. 1-fold over the 125I- GAM or 125I-SAM signals was achieved with-the "2I-protein A assay (3). Class typing of the monoclonal antibodies after bind. ing to fixed cells was done by using a modification ofthe enzymelinked immunosorbent assay (31), with rabbit anti-mouse immunoglobulin class-specific reagents, followed by detection of the bound rabbit antibody with horseradish peroxidase-labeled goat anti-rabbit IgG.(all detector reagents diluted 1.:5; Miles). RESULTS Generation and Screening of Monoclonal Antibodies. After fusion, approximately 5% of the wells had. growing hybrids, C., x E a ~ C. 4 ento NcI-H28 I - 525A5 A NCI-128K. I 4 A O 6- \\ 534F8 2- Proc. Natl. Acad. Sci. USA 78 (1981) NCI4HI28L FIG. 1. Binding of o5monoelonal antibodies to NCM-128sall celllung cancer cell line and to C NA44U8 autologous B-lympho ~ \U F12 blastoid line NCI- H128BL as a function of ascitic fluid dilution. 4-- Points represent the average of quadruplicate determinations in the 2 \ '1I-protein A binding 15 cells. were assay; added to each well. I_H_28B_ Background counts of mouse myeloma IgM A Dilution (log ) (MOPC-14E) were lo g 1) subtracted.

3 Medical Sciences: Cuttitta et al. about one third of the hybrid cultures reacted with all human cells tested, and about 4% showed selective binding to both human lines but not to autologous B-lymphoblastoid cells. Hybrid cultures giving positive reactivity frequently lost activity with time unless repeatedly minicloned and then truly cloned. By these techniques, approximately 25% of the hybrids showing selectivity in the initial screen could be established as stable antibody-producing clonal lines. Culture fluid titers of cloned lines showed maximal plateau binding at titers of 1:1 and 5% of maximal activity at titers of 1:1 to 1:2. Three of the cloned hybrid lines were selected for further study and are designated 525A5, 534F8, and 538F12. Because all were found to be IgM K, rabbit anti-mouse IgM was used with the 125I-protein A assay (3) to detect binding of the mouse monoclonal antibodies. The cloned stabilized lines were injected into pristane-primed mice, and the resultant ascitic fluids had titers over 1-fold greater than those of culture fluid supernatants and were used for characterization. Fig. 1 shows considerable binding of the monoclonal antibodies to line NCI-H128 in the 125I-protein A assay but negligible reactions with an autologous B-lymphoblastoid line (NCI-128BL). Maximal binding to 15 target cells was seen at ascites dilutions of 1:1-4 to 1:1-5, and for further tests the former dilution was used. Reactions of Anti- Monoclonal Antibodies to Various Cell Types. The three monoclonal antibodies were tested for binding to a panel of malignant and nonmalignant human cell Proc. Natl. Acad. Sci. USA 78 (1981) 4593 lines and erythrocytes, as well as rodent cell lines (Tables 1-3). The three monoclonal antibodies bound to all eight ofthe lines tested and to other lung cancer lines, including adenocarcinoma and squamous cell carcinoma, but failed to have significant reactions with human large cell and bronchioloalveolar lung cancer lines (Table 1). In addition, the antibodies did not give significant reactions with a variety of B-lymphoblastoid or skin fibroblast cell lines, including other lines autologous to the lines, other human tumors, fibroblasts, or rodent cell lines (Table 2). Interestingly, these antibodies also bound to three out of three human neuroblastoma and two out of three breast cancer cell lines but failed to react with rodent neuroblastoma, pheochromocytoma, or insulinoma cells (Table 3). When optimal amounts of monoclonal antibody were used, the cell lines, with two exceptions (NCI-H146 and NCI-H6) bound 2- to 1-fold more monoclonal antibody than did the positively reacting adenocarcinoma or squamous carcinoma lung cancer lines or the lines that had converted to large cell carcinoma (Fig. 2 and Table 1). When tested on the same target cell plate, the three monoclonal antibodies differed in their plateau binding levels to the squamous cell cancer line (U1752) and the adenocarcinoma line (NCI-H125), suggesting that they may be directed to different antigenic determinants (Fig. 2). Reactions of Monoclonal Antibodies with Autopsy Specimens. Samples of tumor and normal tissues were obtained at autopsy from several patients with as well as from pa- Table 2. Human and rodent cell lines that had insignificant binding of anti- monoclonal antibodies 525A5, 534F8, and 538F12 Target cells Ref. or source 525A5 534F8 538F12 Target cells Ref. or source 525A5 534F8 538F12 Human target cells Human target cells (continued) B-lymphoblastoid Fetal lung NCI-H128BL * This laboratory <.1 <.1.1 WI <.1 <.1 <.1 NCI-H29BL * This laboratory WI-18-VA2 (transformed NCI-H26BL * This laboratory <.1 <.1 <.1 by simian virus 4) 34 <.1 <.1 <.1 NCI-H134BL * This laboratory Erythrocytes NCI-H51BL MFt Type A+ Normal donor < Burkitt lymphoma (American) Type B+ Normal donor PC119 I. McGrath, NCI < Type O+ Normal donor EW36 I. McGrath, NCI Type B- From NCI-H Multiple myeloma patient U < Rodent cell lines T-cell leukemia/lymphoma Mouse MOLT 4 (lymphoblastic RAG (BALB/c, renal leukemia) cell carcinoma) NCI-H78 (Sezary B82 (C3H, transformed syndrome) 23 <.1 <.1.1 fibroblast) Osteogenic sarcoma L51784R (DBA, J. Bertino,.1.5 <.1 NCI-H135 This laboratory <.1 <.1 <.1 L cell) Yale Mesothelioma Rat NCI-H226 This laboratory <.1 <.1 <.1 NRK-536/5A6 (Osborne- Hypernephroma Mendel rat, kidney) 19 <.1.4 <.1 NCI-H21 This laboratory BRL3E (Buffalo rat, Malignant melanoma hepatocyte) 37 <.1.3 < EN S. Rosenberg, NCI.3 <.1.6 Hamster 628-WE S. Rosenberg, NCI E36 (Chinese hamster, Fibroblasts (skin) transformed lung) NCI-H39SK3t This laboratory BHK (Golden Syrian J. Littlefield, EN S. Rosenberg, NCI hamster, kidney Johns Hopkins 675-ER S. Rosenberg, NCI fibroblast) 2628-SL S. Rosenberg, NCI WE S. Rosenberg, NCI <.1 <.1 <.1 Assays were performed in quadruplicate as described for Table 1. NCI, National Cancer Institute. * B-lymphoblastoid line derived from patient. t B-lymphoblastoid line derived from mycosis fungoides patient. t Skin fibroblast line from patient NCI-H39.

4 4594 Medical Sciences: Cuttitta et al. Table 3. Binding of monoclonal antibodies 525A5, 534F8, and 538F12 to human neuroblastoma and breast cancer cell lines and to comparable neoplasms of rodent origin Target cells Ref. or source 525A5 534F8 538F12 Human cell lines NCI-H NCI-H NCI-H Neuroblastoma CHP-1 D. Glaubiger, NCI; CHP-126 D. Glaubiger, NCI; KO D. Glaubiger, NCI Breast cancer MCF ZR MDA-MB Rodent cell lines Mouse NIE-115 (A/J, neuroblastoma) Rat RIN-m, CL5 (NEDH, insulinoma) PC12 (NEDH, pheochromocytoma Assays were performed in quadruplicate as described for Table 1. NCI, National Cancer Institute. tients without malignant disease, and the samples were tested for their ability to bind the monoclonal antibodies (Table 4). The monoclonal antibodies bound to cells from four separate tumors obtained from the lung and metastatic sites, but failed to give significant reactions with uninvolved lung, liver, skeletal muscle, kidney, or spleen cell preparations. DISCUSSION By screening for hybrid cell-produced antibodies that react with two lines but not with an autologous B-lymphoblastoid cell line we have produced monoclonal antibodies that react with all tumors tested, some other types of human lung cancer, human neuroblastomas, and breast cancer cell lines, but not with a variety ofhuman malignant and nonmalignant tissues and lines or rodent lines. Of interest, the antibodies react with lung cancer cells that had converted from small cell to large cell histology but not with tumors apparently derived from pure large cell lung carcinomas. The monoclonal antibodies gave significant reactions with tumors taken directly from patients without intervening culture, whereas they failed to react with several types of adult normal tissue. Thus, the antigens detected are not dependent on growth in tissue culture for their expression as demonstrated for fetal antigens on human skin fibroblasts (46). However, our studies do not exclude the possibility that the antigens detected may be present on a subpopulation of normal cells such as the Kultschitzky cells, from which are believed to be derived (22, 47). Thus, the antigens detected by our monoclonal antibodies may be a clonal expansion of normally expressed antigens of either adult or fetal nature, as seen for some other tumors (6, 14, 48). The monoclonal antibodies detect determinants present on the tumors and neuroblastomas so far tested, and to a lesser extent, on some non-small cell lung tumors and breast cancer, but not on a variety of other human tumors, including malignant melanomas. At present it is not known if arises from neural crest (as do melanomas and neuroblastomas) or en- 6 V4 x E. -._ oc 4-. IN Proc. Natl. Acad - Sci -4.5 Dilution (log 1 ) FIG. 2. Binding of monoclonal antibodies in ascites fluids to: curves a, NCI-H39 small cell lung cancer line; curves b, U1752, squamous carcinoma lung cancer line; curves c, NCI-H125, adenocarcinoma lung cancer line; curves d, 9812, large cell cancer line. Curves e are maximal binding ratio for the following negative cell lines: A549, bronchioloalveolar lung cancer line; NCI-H128BL, B- lymphoblastoid cell line; RAG, mouse kidney adenocarcinoma cell line. Points represent the average of quadruplicate determinations in the 1251 protein A binding assay; 15 cells were added to each well. Background counts of mouse myeloma IgM A (MOPC-14E) were subtracted. dodermal structures (as do other bronchogenic carcinomas) (22, 47, 49). Absorbed heteroantisera have been prepared against human lung cancers or other tumors that detect antigens that are: (i) shared between and endodermal structures but not with neural crest tissues, (ii) shared between and neural crest derived tumors but not with endodermal tissues, or (iii) apparently restricted to (1-5). Surprisingly, our monoclonal antibodies appear to detect antigenic determinants that are preferentially expressed on, though also present on some endodermal tumors (e.g., adenocarcinoma of the lung) and ectodermal tumors (breast cancer) and some but not all neural crest-derived neoplasms (e.g., neuroblastomas but not melanomas). These monoclonal antibodies demonstrate an unexpected antigenic relationship between neural crest and endodermal tumors. Thus, they should aid in the study of the embryologic origin and interrelationship of lung cancer and other human tumors. In addition, the monoclonal antibodies we have produced appear to have sufficient specificity to be ofpotential clinical, diagnostic, and therapeutic use. Note Added in Proof. Purified, directly l"si-labeled, monoclonal antibodies 534F8 and 538F12 give a significant binding reaction with kidney but not with lung, liver, brain, muscle, gall bladder, urinary bladder, or spleen. We thank Drs. D. Carney and H. Oie for establishing some of the cell lines; Drs. J. Bertino, D. Glaubiger, M. Lippman, J. Littlefield, I. McGrath, J. Ponten, S. Rosenberg, and G. Todaro for donating cell lines; Dr. L. Ortega for autopsy samples; Dr. T. Chused for the gift of GAM, and J. Fedorko, T. Gregorio, H. Sims, S. Stephenson, and J. Arriaga for technical assistance. - USA 78 (1981)

5 Medical Sciences: Cuttitta et al. Table 4. Binding of monoclonal antibodies 525A5, 534F8, and 538F12 to cell lines and autopsy specimens Source of "25I-Labeled "'I-SAM or 125I-GAM monoclonal detector bound, cpm Source of cells antibody* reagentt 525A5 534F8 538F12 Cell lines NCI-H39 AF GAM NCI-H39 TCS SAM NCI-H69 TCS SAM NCI-H128 TCS SAM NCI-H187 TCS SAM B-lymphoblastoid NCI-H128BL TCS SAM NCI-H26 TCS SAM NCI-H51 TCS SAM Autopsy* tumor PET AF GAM MUL TCS SAM GRA AF GAM PVR AF GAM Normal tissue Lung-1 (SNI) AF GAM Lung-2 (HAR) TCS SAM Lung-3 (MUL) TCS SAM Liver-1 (HAR) TCS SAM Liver-2 (SN) AF GAM Skeletal muscle (SNI) AF GAM 1 46 Kidney (SNI) AF GAM Spleen (HAR) TCS SAM Tissues were obtained at autopsy (courtesy of L. Ortega, Washington Veterans Administration Medical Center Laboratory Service), minced with fine scissors, passed through a 3-,m grid mesh screen, taken up in PJNaCl, and dispersed through a 25-gauge needle. The cell suspension was washed three times in PJNaCl, fixed with.25% glutaraldehyde/p]nacl for 5 min, washed twice again, and then adjusted to a 1% vol/vol suspension, and.5 ml of this suspension was added to each well of a polyvinyl microtiter plate and fixed as for the cell lines. '"I-GAM and `mi-sam were used to test the binding of monoclonal antibodies to autopsy specimens because of the large background binding of '25I-protein A to these human tissue samples. Results in cpm are the average of quadruplicate determinations with the backgrounds (2-4 cpm) subtracted. * AF, ascites fluids; TCS, tissue culture supernatant fluids. t To each well, 5,-7, cpm of 1251-labeled GAM or SAM was added. t Different patients are identified by initials. Primary lung tumors and liver metastases were tested. 1. Bell, C. E. & Seetharam, S. (1976) Int. J Cancer 18, Bell, C. E. & Seetharam, S. (1979) Cancer 44, Kelly, B. S. & Levy, J. G. (198) Br. J. Cancer 41, Braatz, J. A., McIntire, K. R., Princler, G. L., Kortright, K. H. & Herberman, R. B. (1978) J. NatL Cancer Inst. 61, Paluch, E. & loachim, H. L. (1978) J. NatL Cancer Inst. 61, Sega, E., Citro, G. & Natali, P. G. (1979)J. NatL Cancer Inst. 62, Akeson, R. (1977) J. Natt Cancer Inst. 58, Tillack, T. W., Rosai, J. & Vervynck, D. J. (1974)J. NatL Cancer Inst. 52, KUhler, G. & Milstein, C. (1975) Nature (London) 256, Koprowski, H., Steplewski, Z., Herlyn, D. & Herlyn, M. (1978) Proc. NatL Acad. Sci. USA 75, Kennett, R. H. & Gilbert, F. (1979) Science 23, Woodbury, R. G., Brown, J. P., Yeh, M. Y., Hellstrom, I. & Hellstr6m, K. E. (198) Proc. NatL Acad. Sci. USA 77, Proc. Natl. Acad. Sci. USA 78 (1981) Schlom, J., Wunderlich, D. & Teramoto, Y. A. (198) Proc. Nati Acad. Sci. USA 77, Levy, R., Dilley, J., Fox, R. I. & Warnke, R. (1979) Proc. Natl Acad. Sci. USA 76, Ritz, J., Pesando, J. M., Notis-McConarty, J., Lazarus, H. & Schlossman, S. F. (198) Nature (London) 283, Nadler, L. M., Stashenko, P., Hardy, R. & Schlossman, S. F. (198) 1. Immunot 125, Herlyn, D. M., Steplewski, Z., Herlyn, M. F. & Koprowski, H. (198) Cancer Res. 4, Gazdar, A. F., Carney, D. N., Russell, E. K., Sims, H. L., Baylin, S. B., Bunn, P. A., Guccion, J. G. & Minna, J. D. (198) Cancer Res. 4, Todaro, G. J., Fryling, C. & DeLarco, J. E. (198) Proc. Natl Acad. Sci. USA 77, Lieber, M., Smith, B., Szakal, A., Nelson-Rees & Todaro, G. (1976) Int. J. Cancer 17, Harris, H. & Hopkinson, D. A. (1976) Handbook of Enzyme Electrophoresis in Human Genetics (American Elsevier, New York), 1st Ed. 22. Gazdar, A. F., Carney, D. N., Guccion, J. G. & Baylin, S. B. (198) in Small Cell Lung Cancer, eds. Greco, A., Bunn, P. A. & Oldham, R. (Grune and Stratton, New York), in press. 23. Gazdar, A. F., Carney, D. N., Bunn, P. A., Russell, E. K., Jaffe, E. S., Schecter, G. P. & Guccion, J. G. (198) Blood 55, Galfre, G., Howe, S. C., Milstein, C., Butcher, G. W. & Howard, J. C. (1977) Nature (London) 266, Kearney, J. F., Radbruch, A., Liesegang, B. & Rajewsky, K. (1979) J. Immunol 123, Kennett, R. H., Denis, K. A., Tung, A. S. & Klinman, N. R. (1978) Curr. Top. Microbiol Immunot 81, Nowinski, R. C., Lostrom, M. E., Tam, M. R., Stone, M. R. & Burnette, W. N. (1979) Virology 93, Potter, M. (1972) Physiol Rev. 52, Hunter, W. M. & Greenwood, F. C. (1962) Nature (London) 194, Brown, J. P., Tamerius, J. D. & Hellstrom, I. (1979)J. Immunol Methods 31, Granfors, H. (1979) J. Clin. Microbiol 9, Minowada, J., Ohnuma, T. & Moore, G. E. (1972)J. Natl Cancer Inst. 49, Hayflick, L. & Moorhead, P. S. (1961) Exp. Cell Res. 25, Weiss, M. C., Ephrussi, B. & Scaletta, L. J. (1968) Proc. Natl Acad. Sci. USA 59, Felluga, B., Claude, A. & Mrena, E. (1969) J. Natl Cancer Inst. 43, Littlefield, J. W. (1966) Exp. Cell Res. 41, Coon, H. G. (1969) Carnegie Inst. Washington Yearb. 67, Gillan, F. D., Roufa, J. D., Beaudet, A. L. & Caskey, C. T. (1972) Genetics 72, Schlesinger, H. R., Gerson, J. F., Moorhead, P. S., Maguire, H. & Hummeler, K. (1976) Cancer Res. 36, Soule, H. D., Vasquez, J., Long, A., Albert, S. & Brenner, M. B. (1973)J. Natl Cancer Inst. 51, Engel, L. W., Young, N. A., Tralka, T. S., Lippman, M. E., O'Brien, S. J. & Joyce, M. J. (1978) Cancer Res. 38, Cailleau, R., Young, R., Olive, M., & Reeves, W. J., Jr. (1974) J. Natl Cancer Inst. 53, Amano, T., Richelson, E. & Nirenberg, M. (1972) Proc. Natl Acad. Sci. USA 69, Gazdar, A. F., Chick, W. L., Oie, H. K., Sims, H. L., King, D. L., Weir, G. C. & Lauris, V. (1979) Proc. Nat. Acad. Sci. USA 77, Greene, L. S. & Tischler, A. S. (1976) Proc. Natt Acad. Sci. USA 73, Thorpe, W. P., Parker, G. A. & Rosenberg, S. A. (1977)J. Immunot 119, Pearse, A. G. & Takor-Takor, T. (1979) Fed. Proc. Fed. Am. Soc. Exp. Biol 38, Lampson, L. A. & Levy, R. (1979) J. Natl. Cancer Inst. 62, Tischler, A. S., Dichter, M. A. & Biales, B. (1976) Science 192, Seeger, R. C., Zeltzer, P. M. & Rayner, S. A. (1979)1. ImmunoL 122,