Figure 6. Lipoproteins from Infected Humans Are Decorated with Antibodies and Can Be Endocytosed Via the FcγRIIa Receptor.
(A) Control (C) and patient (P1 and P2) sera were incubated with protein A-Sepharose beads. Bound material was eluted and subjected to SDS-PAGE and Western blotting for ApoB.
(B) Lipoprotein particles were isolated from control and patient sera, stained for endogenous antibodies present on lipoprotein particles using protein A-gold, and subjected to electron microscopy.
(C) CHO-LDLA cells lacking (−) or transfected with (+) FCγRIIa receptor were incubated with control (C) or patient (P1 and P2) sera. Cell lysates were subjected to SDS-PAGE and Western blotting for endocytosed ApoB (ApoB [Cells]). A proteolytic fragment [56] of ApoB was detected at ~80 kDa. As load controls, the medium was probed for ApoB (ApoB [Medium]), and the cells for calreticulin.