Role of CD14 in TLR2 activation by LTA or aPLAs. (A) HEK-Blue-2 (CD14) and HEK-TLR2 (no CD14) were incubated with 500 μg/mL of the 19 aPLA or control IgG preparations or the 2 aPLA preparations immunopurified on β2GP1 (100 μg/mL) for 16 hours. Then, supernatants were collected and IL-8 was quantified by ELISA. (B-C) Dose-response experiments for LTA (B) or aPLAs from 3 patients (C) were done under the same experimental conditions. Data are expressed as means ± SEM (n = 5). Cell number was verified at the end of the assay using a cell-viability assay (see “HEK cell activation”), and was found to be very similar for both cell lineages (OD_490nm HEK-Blue-2/OD_490nm HEK-TLR2: 1.15 ± 0.03).