[Histone phosphorylation of human lymphocytes after PHA stimulation in relation to age (author's transl)]

Lymphocytes of young and old donors are stimulated by phytohemagglutinin (PHA). The 32P-incorporation into the histones which occurs in the early phase after PHA-stimulation is determined. In lymphocytes of old persons the 32P-incorporation in the histones is diminished by about 50% with respect to the cells of young donors. Furthermore, it could be shown that in the histones prepared from old cells the amount of H1 is much increased. It is postulated that, in old age, the other 4 histones are poorly extractable.