CD5 deficiency leads to an enhanced phosphorylation of Signal Transducer and Activator of Transcription 3 (STAT3) in T lymphocytes and primes them for an increased production of Interleukin-17A (50), a cytokine that has been substantiated as pivotal in the pathogenesis of AD, particularly in its more severe manifestations (51). This evidence concerns the gene CD5 and Alzheimer disease.