In vitro models are required for the study of these cancers, and several cell lines have already been established and characterised (Lafargues & Ozzello, 1958;Soule et al., 1973;Cailleau et al., 1974;Engel et al., 1978;Whitehead et al., 1983;Yamane et al., 1984;Chu et al., 1985;Vandewalle et al., 1987). Nevertheless, owing to the heterogenity and the diversity of mammary cancers, a great number of cell models is necessary to understand the reasons for this diversity and the effect of anticancer drugs on tumour cells.Cytogenetic studies of mammary adenocarcinoma cell lines are essential for comprehension of the pathogenesis of these cancers (Trent, 1985;Gebhart et al., 1986). The implication of chromosomal alterations in these pathologies has opened a new and promising route towards better knowledge of these cancers (Cervenka & Koulischer, 1973). Chromosomal alterations are generally numerous, and markers often demonstrate hyperploidy in these cancers (Sandberg, 1980). Demonstration of the minimum genetic alterations indispensable for cell transformation is difficult, and might be easier on cells with a karyotype closer to normal. Sandberg and Wolman mentioned the existence of such cells, but most of their results concerned karyotype studies without chromosome banding (Sandberg, 1980;Wolman, 1983 [-', hyaluronidase 25 IU for 20 ml, Hepes buffer 4.8 g 1' in distilled water). Cells were then fixed in acetic acid:methanol (1:3) and dropped onto grease-free, cooled slides for chromosome counting and examination. R bands were obtained by heat denaturation of the chromosomes according to the method of Dutrillaux and Lejeune (1971). Xenografted CAL51 cells were plated and studied in vitro in the same manner.
The specific anti-tumor cell-mediated immunity was investigated in mice bearing syngeneic transplantable tumors and submitted to local X-irradiation. For this purpose, in vitro tests evaluating the immunologically specific inhibitory efSect of lymphoid cells on target tumor cells were performed. The use of lymphoid cells obtained by peritoneal washings permitted us to follow the evolution of the immune status in the same mice during and after the treatment. At the same time when the non-treated tumor-bearing controls were immunologically inactive, being in an immunological '' eclipse " phase, a significant reactivation of cellular immunity could be detected in a parallel series of mice, submitted to X-ray treatment, as soon as the tumors began to decrease in size. This activity could still be detected more than 2 months after complete remission of the tumors. If a decrease in this immunity was observed, it was always premonitory of tumor recurrences and the immunological status of the relapsing animals became comparable to that of the tumor-bearing non-treated controls. The results obtained were very similar whether the whole population of peritoneal cells or only the '' non-adhering "fraction of it was used for in vitro tests. However, in the latter case, the immunological reactivation .following X-ray treatment appeared to begin earlier and to last longer. When compared with the surgically treated animals, the mice cured by X-rays showed an earlier immunological reactivation. This reactivation, once it occurred, lasted in both cases for a comparable period after the total elimination of the tumors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.