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Antigen Presenting Cells (APCs)
dsRNA
Denotes double-stranded RNA, known as the genome of retro-viruses.
Endotoxin
Lipopolysaccharides (LPS) that are an integral part of the outer cell envelope membrane
of gram-negative bacteria. They evoke toxic and pyrogenic effects and cause sepsis.
Epitope
SpeciFc amino acid sequence of foreign or self-antigens that an antibody (B-cell
epitope) or a T-cell receptor (T-cell epitope) recognizes, binds to, and reacts against.
Germinal Center
Sites in secondary lymphoid organs where activated B cells undergo proliferation,
selection, maturation, and apoptosis.
HLA
Acronym for human leukocyte antigen, denoting the human MHC molecules.
Humoral Immunity
Immune response involving B cells that produce antibodies.
Immunoglobulin
A protein produced by a B cell that binds to a speciFc antigen leading to attack by the
immune system.
LPS
Lipopolysaccharide (cf. endotoxin).
Lymphatic System
A network of vessels that is separate from the blood circulation. It includes the lymph
nodes that are the command centers of the immune system.
MHC
Major histocompatibility complex – a gene cluster encoding MHC molecules,
originally described as antigens responsible for transplant rejection. MHC molecules
bind antigenic peptides in order to activate T cells in an antigen-speciFc manner.
Peptide
Short fragment of a protein. On binding to MHC molecules, it can activate T cells and
thereby becomes antigenic.
Processing
Set of activities of an antigen presenting cell encompassing proteolysis of an antigen,
generation of antigen peptides, peptide loading onto MHC molecules, and transport of
MHC-peptide complexes to the cell surface.
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