Malignant lymphoma antigen expressed in nude mouse tumor cells derived from carcinogen-transformed Bloom's syndrome B-lymphoblastoid cell lines

From nude mouse tumors, in which malignantly transformed Bloom's syndrome (BS) B-lymphoblastoid cell lines were successfully transplanted into s.c. tissues, we have detected strong expression of malignant lymphoma (ML)-associated antigen on the cell surface, by using diluted sera of ML patients and indirect immunofluorescence. Even though carcinogen-treated BS B-lymphoblastoid cell lines expressed various types of cancer antigens (ML, ovarian cancer, stomach cancer, lung cancer, liver cancer, etc.) on the cell membrane as a mixed population (Y. Shiraishi and H. Soma, Proc. Natl. Acad. Sci. USA, 85:8211-8215, 1988), the finding that BS malignant cells originating from nude mouse tumors expressed specific ML-associated antigen seemed significant for ML diagnosis. BS nude mouse tumors were successively transplantable from nude mice to nude mice (100%). Histopathological studies using an electron microscope demonstrated that most tumor cells in s.c. tissues of nude mice were lymphoid malignant cells. Gel electrophoresis and Western blotting analyses demonstrated that the antigen which characterized ML was a single band (Mr 97,000) and did not cross-react with the sera of other cancer patients or with normal sera. Chromosome analysis showed that the cell clones with ML-associated antigen had marker chromosomes involving t(6;?)(p25;?),t(9;?)(q34;?), del(10)(p13),t(12;14)(q24;q11). The expression of ML-associated antigen was also discussed in relation to the marker chromosomes.