CD28 and Alzheimer disease: Even though we thus demonstrated the modulatory effect of every tested β-amyloid for CD4+CD28+ cells, we found no significant differences between AD patients and healthy elderly volunteers concerning the enhancement of cell cycle parameters neither in the numbers of divisions per cell nor in other dynamic features of cell cycle available in the DCT method [18], including proliferation index, number of cell precursors, the G0→G1 transition time or the percentage of proliferating cells (not shown).