Wrong Resemblance? Role of the Immune System in the Biocompatibility of Nanostructured Materials - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 289

and biocompatibility, it is important to note that the choice of
coatings for nanoparticles and other nanostructured devices
often are biopolymers, which are targets for T cell-independent
antibody formation, mainly because these biopolymers are of a non-
proteineous nature.
10.2.2 AntibodyEff ector Mechanisms and the
Activation of the Complement System
The binding of antibodies to antigens triggers several functions of the
immune system, usually referred to as “eff ector mechanisms,” which
depends on the isotype of the antibody. These mechanisms comprise
the ability to (1) neutralize function of intruding microorganisms
or other foreign bodies, (2) facilitate the uptake of foreign bodies
through receptors on the surface leukocytes that bind antibodies, or
(3) activation of the complement system as discussed below in this
section.
Antibodies are able to neutralize functions of infectious
microbial organisms by simple binding to key molecules of these
organisms. Several studies have demonstrated that nanoparticle
formulations of various antigens enhance the immune response,
i.e., antibody synthesis, compared with the response of the naked
antigen [14-16]. It is unclear, however, if nanomaterials enhance
the immune response compared with particulate formulations with
larger particles, which routinely are used as adjuvants in vaccines.
While the particle-enhanced immune response may serve certain
purposes in vaccine formulations, it is likely that the strong response
could generate antibodies that would interfere with other functions
of nanoparticles, e.g., the targeting to specific tissues and drug
release. Similarly, binding of antibodies to these or other types of
nanomaterials may also be speculated to alter chemical properties
of surfaces with regard to hydrophilicity, surface roughness, and
the presentation of cues for cell adhesion. Since the function of
many nanomaterials critically depends on these properties, such
antibody “biofouling” could potentially incapacitate the function of
the material [17]. However, the current insight into such processes
is limited.
A significant eff ector mechanism of antibodies involves a
processes referred to as “opsonization” derived from an ancient
Greek word meaning “preparing for food.” A group of leukocytes that