Chromosome abnormalities in lymphatic leukemia in cattle.

Abstract

THE specific change in the chromosome complement reported by Gustavsson and Rockborn1 in three cases of overt leukaemia in cattle is extremely interesting, but care should be taken in identifying the chromosome changes with the neoplastic condition. This may not have been the intention of the authors, but it is an important distinction for the following reasons; (1) We have studied the chromosomes in more than twenty cases of lymphosarcoma (lymphatic leukaemia) in cattle, nine of which have been reported2, and in only two cases, one described by us2 and the other by Basrur et al.3, have similar chromosomal changes been observed; namely, an additional submetacentric chromosome and a minute chromosome in place of one of the small acrocentric chromosomes. (2) In the three cases reported by Gustavsson and Rock- born, all the mitoses from the peripheral blood leucocyte cultures showed the same chromosomal change. This would be unusual if the chromosomal change was associated with the neoplasia, because in our experience, even when chromosomal changes occur in the peripheral blood leucocytes of cattle with lymphosarcoma, a number of cells with apparently normal karyotypes are always present in cultures to which phytohaemagglutinin has been added. (3) The finding of the same chromosomal change in cells from the bone marrow and kidney of the foetus of one of the cows and in peripheral blood leucocytes of the three cows would seem to offer further evidence that the chromosomal change was generalized and not confined to the cells of the lymphatic system or associated with the neoplastic condition. Chromosomal analyses of other cells from the cows, for example, bone marrow cells and fibroblasts, in addition to the peripheral blood leucocytes, would have helped to throw light on the significance of the change in the chromosome complement and on the possibility that it may have been inherited.