Complement activation during low-density lipoprotein apheresis

Complement system activation was investigated in two girls with familial homozygous hypercholesterolemia undergoing two monthly sessions on LA15 or LA40 (Kaneka liposorber). We determined blood levels of C3c and C3a, leukocyte counts, and plasma levels of C3c and C3a in the extracorporeal circulation device at the start of the sessions and 15 and either 60 or 120 min into them. Sequential eluates were collected from LA40 at the end of the sessions (0.5M NaCl, 1M hydroxylamine). Anaphylatoxin C3a increased throughout, especially with LA40. As previously reported, C3a was trapped in the dextran column but was noticeably present in efferent plasma. Besides many proteins, nonnative complement fragments bearing C3a and C3d antigens were detected in almost all the eluates, suggesting possible in situ complement activation. Practically, complement activation induced by the first filter is a risk; long-term side effects may arise from this extracorporeal circulation device.