Absence of distinct dots in chromosomes of differentiated lymphocytes

SUMMARY

Peripheral blood lymphocytes were cultured by conventional methods in order to harvest metaphase cells. Slides were air dried and incubated in phosphate buffer at high temperature in order to study chromosome ‘dots’. Our previous investigations had indicated that chromosomes of undifferentiated cells (lymphoblasts) contained numerous heterochromatic ‘dots’, while chromosomes of patients with acute lymphoblastic leukemia (ALL) contained an elevated dot frequency. In this investigation, however, chromosomes of differentiated lymphocytes were found to contain no distinct dots. This finding indicates that a reduction of heterochromatic dots in chromosomes is correlative to cellular differentiation.