CD4 and Alzheimer disease: To summarize all of the above, while elevated levels of Aβ-specific T cells have been detected in the blood and an accumulation of T cells (including some clonally expanded CD8 T cells) was found in the brains and CSF of patients with AD, the presence of Aβ-specific CD4 and CD8 T cells in the brains of AD patients has not been yet reported.