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datory panel of target tissues or cells. Central computer analysis and other supporting data allowed the assignment of 33 mAbs to seven clusters. Two of the antigens identified have been cloned while two more have been defined as carbohydrate epitopes. The results allow comparison of new mAbs against lung cancer with existing onesand are beginning to provide a description of the antigenic structure of the SCLC cell surface.

Monoclon~l antibodies defining the cluster-5A small cell lung car- cinoma antigen Waihcl R, O’Hara CJ, Stabel RA. Division of Oncology, Departmenr of Medicine, University Hospiral. CH-8091 Zurich. Br J Cancer 1991 63 Suppl 1429-32.

The cluster-5A antigen on small cell lung cancer has been previously identified by the murine IgG(2.a) monoclonal antibody SWA20. We now describe four new murine monoclonal antibodies, SEN3 (IgG,), SENl 1 (IgG& SEN12(IgG(2b)) and SEN3 1 (IgG,) which recognise the same antigen. ‘Ihe antibodies have similar binding characteristics as antibody SWA20 on cell lines and on a limited number of frozen sections of human tissues when examined by immunofluorescence and immunohistochemistry. Radioimmunoassays on fixed cells showed competitive binding of all antibodies with radiolabellexl antibody SWA20. Solid phase radioimmunoassays with the new antibodies on biochemi- cally treated target cells showed similar characteristics to antibody SWA20, including sensitivity to treatment with periodate. and neuram- inidase. Immuooblottiug experiments with all antibodies revealed similar bandsat molecular weightsof 18O,lOOand50 kD. Binding studiesafter incubation of cells with inhibitors of glycopmtcin synthesis suggest the cluster-5A antigen to be a N-linked sialoglycoprotein.

Modulation of the cluster 1 and mucin antigens in human small cell lung cancer and other epithelial tumour cell lines after treatment with the differentiation inducing agent, sodium butyrate Hay FG, Duncan LW, Langdon SP, Leonard RCF. Imperial Cancer Research Fund Medical Oncology Unit. Western General Hospiml. CreweRoad, Edinburgh EH4 2XlJ. Br J Cancer 1991;63 Suppll4: 33- 5.

The expression of the human small cell lung cancer (SCLC) cluster 1 antigen and the human milk fat globule membrane (HMFG) antigen were stodied in three SCLC, three lung adenocarcinoma, six ovarian adenwarcinoma and three colorectal adenocarcinoma cell lines before and after culture in the presence of the differentiation inducing agent, sodium butyrate. Before treatment. only SCLC and well differentiated ovarian cell lines expressed the cluster 1 antigen. After 4 days culture with sodium butyrate, expression of cluster 1 antigen was induced in poorly differentiated ovarian, colorcctal and lung adenocaxinoma cell lines whereas existing antigen expression was enhanced in SCLC and well differentiated ovarian cell lines. The expression of the HMFG antigen was also modified. Induction of cluster 1 antigen correlated with increased levels of alkaline phospbatase in the treated cell lines, this enzyme being associated with a more differentiated state in colon and ovarian carcinoma cell lines. The pattern of induction of cluster 1 antigen expression suggests that several different epitopes of this antigen are recognised by the ten SCLC cluster 1 antibodies studied.

and morphology of the variant subtype of SCLC (SCLC-v). Further- more, insertion of the v-Ha-ras oncogene into such SCLC-v cells has been found to induce features typical of NSCLC. We have used classic SCLC cells transfectcd with c-myc, or co-transfomwd with c-myc and v-Ha-ras, to examine the expression of characteristics SCLC cluster antigens. Flow cytometric assays reveal that SCLC cells co-trans- formed with c-myc and v-Ha-ras oncogenes down-modulate. SC-l, SC- 2 and SC-SA surface antigens to levels approaching, in some cases, those seen with NSCLC cells. The SC-4 surface antigen is not modu- lated by activation of these oncogenes. These findings support clinical and laboratory observations that important transitions can occur be- tween subtypes of human lung cancer cells, and that these shifts may play a role in the clinical progression of lung cancer.

Selection of anti-SCLC antibodies for diagnosis of bone marrow metastasis Myklebust AT, Beiske K, Pharo A, De L, Davies C, Aamdal S, Fodstad 0. In&me for Cancer Research. 0310 Oslo 3. Br J Cancer 1991;63 Suppl 14:49-53.

The binding profile of 17 monoclonal antibodies (MAbs) to small lung cancer cell lines and normal bone marrow and peripheral blood cells was studied by immunocytochemistry and flow cytomeuy. At antibody concentrations that stained PJD tumour cells, only four MAbs (MGCI, MOC31, NrLulO. 81A6) were devoidofcross-reactivity with normal cells, whereas significant binding to subtypes of bone marrow and blood cells was seen for 13 antibodies. For theeigbt most promising MAbs the binding to ten SCLC cell lines was moderate to strong in 47 MAb/cell line combinations, and low or insignificant in 33 combina- tions. Three cell lines lacked antigen for all MAbs studied. Flow cytometry was significantly less sensitive than immunocytochemistry in assessing MAb binding to both normal and tumour cells. The antigen expression was for several MAbs higher in exponentially growing tumour cells than in cells in stationary growth phase. Seven of the MAbs, which originally showed low to moderate cross-reactivity with normal cells, were titrated down to the lowest concentrations at which they stained H-146 tumour cells with high levels of antigen expression. At these concentrations live (MLuCl , Oat-l, SM-1 , NCC-Lu-243, LAM2) of the seven Mabs showed acceptably low binding to bone marrow cells. At optimal concentrations altogether four to nine of the 17 antibodies studied may be used to detect tumourcell involvement in bone marrow of SCLC patients.

Modulation of neurocnducrine surface antigens in oacogene-acti- vated small cell lung cancer lines Doyle LA, Mabry M, Stahel RA, Waibel R, Goldstein LH. Universily of Maryland Cancer Centre, Baldmore. MD 21201. Br J Cancer 1991;63 Suppl l&39-42.

Differential expression of antigens by human small cell lung carci- noma in sections of turnour and in serous effusions Moss F, Bobrow L, Happcrfield L, Souhami R, Beverley P. Chesl and Allergy Clinic, St Mary’s Hospikd, PraedSweet. London W2 1NY. Br J Cancer 1991;63 Suppl 1454-S.

Antigen expression by human small cell lung carcinoma cells in serouseffusionswasdeterminedbystainingsmearsofcellswithapanel of four monoclonal antibodies including UJI 3A (cluster 1 antigen) and CAM 5.2 (anti-cytokeratin) using an immunoalkaline phosphatase technique. This was quantified by counting the proportion of stained and unstained tumour cells and was compared with that of small cell lung carcinoma in sections of solid tumour. Differential expression of am&en exoression was noted with sienificamlv fewer small cell carci- nom: cell; in serous effusions stainiig with I?Jl3A or CAM 5.2. The reasons for this differential expression are unknown, but may reflect adaptation to a different environment or be a prerequisite for spread to scrous space.

Small cell lung cancer (SCLC) manifests a number of neuroendo- crine differentiation features and antigenic characteristics that distin- guish the tumour from non-small ceU lung cancer (NSCLC). Several surface antigens on SCLC cells, identified by clusters of monoclonal antibodies (MAbs), distinguish SCLC and orher neumendccrine tu- mours of NSCLC. Stable transfection of the c-myc pmto-oncogene has been reported to confer upon classic SCLC cells the growth properties

Measurement of murine IgG and IgM concentrations in the SCLC MAb panel; effects of concentration on sensitivity and specificity Manderino GL. Cancer and Immunology Research. Abbott Lzboralo- ries, Norrh Chicago, IL 6Ol%4. Br J Cancer 1991;63 Suppl 14:64-6.

Sensitive, solid-phase enzyme immunoassays for detecting murine IgM and IgG were developed and used to quantitate immunoglobulin concentrations in the SCLC MAb panel. Among the IgM MAbs. most