Biomedical Engineering Reference
In-Depth Information
nanostructures with graphene layers arranged as stacked cones, cups, or plates. These carbon
nanofibers when wrapped into perfect cylinders with graphene layers are called carbon nanotubes
(CNTs). The most common form of carbon NPs is CNTs. They consist of carbon atoms arranged in
a series of condensed benzene rings wrapped in a tubular form. Depending on the number of sheets
rolled, there are two types of CNTs:
single-walled carbon nanotubes
(SWCNTs) and
multiwalled
carbon nanotubes
(MWCNTs). But regardless of its type, CNTs possess many significant properties
such as high aspect ratio, tremendous strength, ultra-light weight, high thermal conductivity, and
electronic properties ranging from metallic to semiconducting [2].
Recent research show a growing area of investigation on toxicity related to the exposure of NPs
within the human body with the increased use of nanotechnology in drug delivery and environmen-
tal science. These NPs enter the body either accidentally from the environment or by the deliberate
placing of NPs within the body through drug delivery or different biomedical applications. The
consideration of the immunomodulating potential of NPs, including both immunosuppressive and
immunostimulatory after binding with plasma protein, is a nascent field of research and hence much
data have not been documented. Observation from different
in vitro
and
in vivo
toxicity studies
showed inflammation, cytokine production, oxidative stress, cytoskeletal changes, apoptosis, and
alteration in vesicular trafficking, in gene expression, and cell signaling [3].
20.2 IMMUNOLOGY
Immunology is the study of the relationship between body system, pathogens, and immunity. The
science of immunology deals with organs and cellular components that comprise the immune sys-
tem and their function and interaction. The immune system has been divided into two types: (1)
innate immune system and (2) acquired or adaptive immune system. Again, an acquired immune
system can be classified into humoral and cellular components [4] (Figure 20.1).
The various parts of the immune system are connected via the blood and lymphatic systems. Bone
marrow, spleen, lymph nodes, thymus, and mucosa-associated lymphoid tissues are the main organs
of the immune system and are involved in the manufacturing, maturation, differentiation, prolifera-
tion, and storage of immune cells. The blood is composed of red and white blood corpuscles together
with other molecules such as various complement proteins and immunoglobulins. White blood cor-
puscles, also known as leukocytes, play a major role in the immune system. They are made up mainly
of polymorphonuclear granulocytes (PMNs), in addition to monocytes, natural killer cells, B and
T lymphocytes. PMNs are composed of neutrophils (phagocytic cells), eosinophils, and basophils.
T and B lymphocytes, natural killer cells, and PMNs are the main cells of the immune system. In
addition, dendritic cells and macrophages are essential components of the immune system that act as
a chemical agent or antigen-presenting cells (APCs). Mononuclear phagocytic system (MPS) is the
name given to the part of the immune system that consists of phagocytic cells, such as blood mono-
cytes and macrophages accumulated in lymph nodes, liver, spleen, and other tissues [4] (Figure 20.2).
The humoral (antibody) response is characterized as the interaction between antibody and anti-
gens. Antibodies are specific proteins released from a particular class of immune cells called B lym-
phocytes. Antigens are defined as anything that enkindles generation of antibodies; hence, they are
Immune system
Innate immune system
Adaptive/acquired immune system
Humoral (antibody)
Cellular components
FIGURE 20.1
Classification of immune system.
