CD68 and Alzheimer disease: A potential relevance of monocyte-derived cells beyond T cells in AD was provided by observations of Kiekens et al., where an increase in macrophage numbers, identified by the macrophage differentiation marker CD68 and expression of mannose receptors, was detected in a model of acute AD as well as in skin biopsies of chronic, inflamed, lesional AD skin by immunohistochemistry.