Experiments with fluorescent chromosome staining in Burkitt tumors

The new fluorescence analysis by acridin derivatives, designed by Caspersson and collaborators, has been applied to a number of Burkitt lymphomas and, as a background, to leukocyte cultures from healthy subjects. In our experiments, quinacrine dihydrochloride (Q, “atebrin”) was used as fluorescent stain. It gave essentially the same chromosomal patterns as quinacrine mustard (QM), widely used by the Caspersson group. The fluorescence patterns of the lymphomas were in general agreement with those of normal cells, with some exceptions, however. Thus, a male tumor with an apparent Y chromosome in light microscopy showed only traces of the Y fluorescence. In one tumor, three marker chromosomes had fluorescence patterns indicating that they were derived from three A group chromosomes, one normal No. 1 and two No. 3, missing from the stemline karyotype. Strongly fluorescent regions in autosomes behaved in two ways: (1) Those on a proximal segment of No. 3 were present in both homologues, in one only or in none of them. Each individual tumor or blood culture was characterized by one or the other of these combinations. (2) Those on the short arm of No. 4 and on the satellites of No. 14 and 22 were found only in one of the homologues of a pair. A few potential applications of the fluorescence technique were discussed.