Second, it was reported that chronic lesions also express moderate levels of the Th1 cell cytokine IFN-γ; thus, the T cell response present in AD is not only Th2-polarized but may lead to heterogeneous cytokine production involving Th1 cell cytokines and Th1 downstream T-box transcription factor 21 (Tbx21, T-bet) [10]. Here, TBX21 is linked to Alzheimer disease.