203
inner walls it reaches the inside of ad-
jacent rooms. The following dates give rise to the suspicion that as a result of the described modern developments in regions of moderate and cold temperatu- res, 'homemade' radioactivity may consti- tute an important additional source of bronchial carcinoma.
Transforming Potential of a Retrovirus Isolated from Lung Carcinoma of Sheep. Safran, N., Zimber, A., Irving, S.G., Perk, K. The Koret School of Veterinary Medicine, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel. Int. J. Cancer 35: 499-504, 1985.
A retrovirus isolated from experimen- tally induced sheep lung carcinoma (SPCTV) was propagated in chronically infected Himalayan tahr ovarian cells and in nor- mal sheep lung cells. Follow-up of infec- tion of the cells with SPCTV showed the appearance of syncytium, plaque formation, partial recovery and the establishment of a chronic infection. Virus-associated reverse transcriptase activity in the medium fluctuated but remained at a con- stantly high level at the stage of chro- nic infection. Stages of type-C virus morphogenesis were demonstrated by elec- tron microscopy. The viral genome was de- tected in both the nucleus and cytoplasm by in situ hybridization. Chronically in- fected cells formed colonies when plated in soft agar. Following subcutaneous in- oculation of chronically infected cells (of fibroblast origin) into nude mice, lymphoid tumors developed at the site of inoculation and in vital organs.
3, BASIC BIOLOGY
Purification from a Human Lung Cancer Cell Line of a Water Soluble Nblecule Mediating Leukocyte Adherence Inhibition for Patients with Lung Cancer. Thomson, D.M.P., Sutherland, M., Durko, M. et al. Montreal General Hospital, Montreal, Que. H3G IA4, Canada. Int. J. Cancer 35: 707-714, 1985.
Soluble lung tumor activity as deter- mined by LAI was enriched by physiocoche- mical methods from chemically-defined spent medium of a lung cancer cell line (NCI-H69). To identify the polypeptide carrying the antigenic determinant, sple- nic lymphocytes of BALB/c mice were immu- nized with the enriched isolate and hy- bridized with mouse plasmacytoma cells. Eight hybrids were cloned successfully and produced MAbs that immunoprecipi- rated principally a single chain of M (r) 40,000 (p40) as well as minor chains of M(r) 25,000 (p25) and M (r) 13,000 (p13)
which were probably degradation products of p40.
On 2D gels, p40 was composed of 7 spots with a pI of 6.3 to 7.6, which was not altered by neuramini- dase digestion. Affinity chromatography with MAb anti-p40 absorbed p40 and LAI activity. The bound and recovered fraction was enriched for p40 and LAI activity. Affinity-purified p40 also contained the previously identified p25 and p13 as well as a M(r) 32,000 peptide (p32). MAb anti-p40 was direc- ted to a common framework determination on p40 since MAb anti-p40 bound to cancer cells from other organs. The comparatively lung cancer organ-speci- fic determinant recognized by leukocytes from lung cancer patients was not recognized by the MAb. Affinity-purified p40 triggered LAI for leukocytes from patients with lung cancer but not for leuko- cytes from control subjects or patients with colon cancer or malignant melanoma in r~gorous blind te- sting. Cross-reactivity was observed with leuko- cytes from patients with breast cancer. LAI activity of affinity-purified p40 seems unlikely to result from an unidentified impurity. Thus a p40 molecule has been purified that is expressed on the membra- nes of lung cancer cells and triggers immunological- ly-mediated LAI.
Genetic Instability of Cell Lines Derived from a Single H~nan Small Cell Carcinoma of the Lung. Engelholm, S.A., Vindel~v, L.L., Spang-Thomsen, M. et al. University Institute of Pathological Anatomy, University of Copenhagen, DK-2100 Copenhagen ~, Denmark. Eur. J. Cancer Clin. Oncol. 21: 815-824,
1985. Specimens from a human small cell carcinoma of
the lung were established as a cell line in vitro. Flow cytometric DNA analysis demonstrated only one tumor cell population in the parent tumor as well as in the early passages in vitro. After six passa- ges in vitro, two new subpopulations with different DNA content appeared. By cloning, permanent cell lines were established from the new subpopulations, whereas the original population stopped growing. The cloned cell lines were characterized by mor- phology, chromosomes analysis, electron microscopy and plating efficiency; the stability of the DNA content was examined regularly by flow cytometric DNA analysis and instability was found in one of the cloned cell lines. Chromosome analysis showed that the cloned cell lines consisted of more than one population after 17 in vitro passages. Both cloned cell lines produced tumors in nude mice. Genetic instability was demonstrated in these mouse- grown tumors as well. Development of resistance to antineoplastic treatment may be due to heterogenei- ty in sensitivity among subpopulations in a tumor. Isolation of populations with different DNA con- tents allows the study of interaction between sub- populations and the observations provide evidence in support of the hypothesis of clonal evolution.
Stability and Utility of the Unique Human Small Cell Carcinoma Line SHP-77. Koros, A.M.C., Klein, E.C., Pan, S. et al. Depart- ment of Infectious Diseases, Graduate School of
