Untitled - D Ank Unlimited

despecification 225 dextran
with the antigen during antigen presentation. Allelic variation
permits these contact residues to vary, which is one
of the factors in histocompatibility molecule selection of a
particular epitope that is being presented.
despecification
A method for reducing the antigenicity of therapeutic antisera
prepared in one species and used in another. To render
immunoglobulin molecules less immunogenic in a heterologous
recipient, they may be treated with pepsin to remove
the most immunogenic portion of the molecule (i.e., the Fc
fragment) but leave intact the antigen bonding region (i.e.,
F(ab′) 2 fragments) that retain their antitoxic properties. Had
such a treatment been available earlier in the 20th century,
serum sickness induced by horse antitoxin administered to
human patients as a treatment for diphtheria would have
been greatly reduced.
DETC
Dendritic epidermal T cells. Refer to intraepithelial
lymphocytes.
determinant groups
Chemical mosaics found on macromolecular antigens that
induce an immune response. Also called epitopes.
determinant selection model
Concept that immune response variability to a given antigen
among different individuals is attributable to the ability of
each person’s MHC alleles to successfully bind and present
that antigen’s determinants.
determinant spreading
An amplification mechanism in inflammatory autoimmune
disease in which the initial T lymphocyte response
diversifies through induction of T cells against additional
autoantigenic determinants. The response to the original
epitope is followed by intramolecular spreading, the activation
of T lymphocytes for other cryptic or subdominant
self determinants of the same antigen during chronic and
progressive disease; intermolecular spreading involves
epitopes on other unrelated self antigens. A multideterminant
protein antigen has dominant, subdominant, and
cryptic T cell epitopes. The dominant epitopes are most
efficiently processed and presented from native antigen.
By contrast, cryptic determinants are inefficiently
processed and/or presented. Only by immunization with
a peptide that often requires no additional processing
can a response to a cryptic determinant be mounted.
Subdominant determinants fall between these two types.
deuterostomes
Coelomate-derived animals that developed into the vertebrates.
α (1 6)
linkage
Glucose
α (1 3)
linkage
α (1–6) linkages and β (1–3) linkages in dextran molecule.
dextran
Polysaccharides of high molecular weight comprised of
d-glucohomopolymers with α glycoside linkages, principally
α-1,6 bonds. Dextrans serve as murine B lymphocyte mitogens.
Some dextrans may also serve as thymus-independent
C O
HC R 1
HC R 3
NH
NH
O C
NH
(a) (b)
HC (CH2 ) 4 -N
H
Determinant groups. (a) Conjugated protein with substituents. (b) Broken lines indicate haptenic group. Solid line indicates antigenic determinant.
C O
O 2 N
NO 2
D