TLR2- or TLR4-dependent HEK activation by aPLA and control IgG (CTL). HEK-Blue-2 or HEK-Blue-4 was incubated with 500 μg/mL of aPLA preparations from 32 patients or 19 control IgG preparations for 16 hours. Cell activation was quantified by measuring the change in OD at 650 nm, which corresponds to sAP activity. The activation of HEK-Blue-2 and HEK-Blue-4 by aPLAs was significantly different (P < .0001 by 2-way ANOVA and paired t test).