iEMs incubated with aPL plasma (B, D) and plasma from a healthy donor (A, C) visualized with bright field microscopy. Aggregate formation seen after incubation with aPL plasma (B) is hardly seen with normal plasma (A); Agglutinate formation after addition of anti-hIgG/anti-hC3d (C, D) is amplified in aPL plasma (D) compared to normal plasma (C). Examples of aggregates are indicated with white arrows.