CD14 and Alzheimer disease: In addition, because the immune receptor Toll-like receptor 4 (TLR4) is expressed in platelets [18] and is involved in AD progression [19], the TLR4/CD14 agonist LPS was tested and displayed the ability to stimulate the release of Aβ1-42 (Figure 1A) and, to a lower extent, Aβ1-40 by platelets (Figure 1B).