Biomedical Engineering Reference
In-Depth Information
Figure 11.4
Mechanism of complement activation-related pseudoallergy
(CARPA) caused by liposomes and micelles. Crel-Cremophor EL, PS80-
polysorbate 80, R-receptor. See also Color Insert.
11.5
Immunogenicity of Liposomes
Being built from natural, or natural-like (regarding stereochemistry
and composition), synthetic or semisynthetic phospholipids,
liposomes are generally not immunogenic. This statement is in
apparent conflict with the intense ongoing R&D of liposomal vaccines;
however, it should not be forgotten that these vaccines include
protein, carbohydrate, or lipid antigens and adjuvants as well as other
mediators, such as lipid A, muramyl dipeptide and its derivatives,
interleukin-1 and interleukin-2 in addition to the phospholipid bilayer,
which also acts as an adjuvant in its own right [3]. When adjuvants are
used, specific antibodies are induced against all liposome components,
including structural (phospho)lipids, cholesterol and even squalene, a
cholesterol precursor triterpene [5-7, 65].
As for the underlying cause of the intrinsic adjuvant capability
of phospholipid bilayers, promoting specific immune response to
liposomal antigens and non-antigenic lipid components (without
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