Chromatin bodies in multidrug resistant hybrid cells have centromeres and originate from homogeneously staining regions.

Antikinetochore antibodies from patients with the CREST syndrome of scleroderma were used as probes to study homogeneously staining regions (HSRs) in multidrug resistant (MDR) mouse tumor cells, and chromatin bodies (CBs) in MDR mouse-hamster hybrid cells. In one mouse tumor line the C-band positive HSR showed antigenic properties and displayed many weekly fluorescent spots, i.e. it contained kinetochore proteins. The immunofluorescence pattern of the HSR could also be observed in interphase nuclei. The C-band positive CBs of the hybrid cells had active centromeres, as shown by double kinetochore spots. These results support our hypothesis that CBs originate from C-band positive HSRs.