Soluble OX40 and sOX40L were measured in serum from patients with AD and from HC with a sOX40 ELISA kit (cat. no. BMS296TEN, eBioscience (eBioscience, San Diego, CA, USA)) and with an inhouse sOX40L ELISA, as described previously (7 (link), 17 (link)). OD values were read by a Thermo Scientific Multiscan GO reader (Thermo Scientific, Waltham, MA, USA) at 450 nm, with 570 nm as a reference. The minimum detectable level of sOX40 and sOX40L was determined by the cut-off value of the standard curve. The lowest detectable levels of sOX40 and sOX40L were 1.9 and 0.039 ng/ml, respectively.