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suppressor T cells (Ts cells) 672 SV40 (simian virus 40)
suppressor T cells (Ts cells)
A T lymphocyte subpopulation that diminishes or suppresses
antibody formation by B cells or downregulates
the ability of T lymphocytes to mount cellular immune
responses. Ts cells may induce suppression specific for
antigen or idiotype or nonspecific suppression. Some CD8 +
T lymphocytes diminish T helper CD4 + lymphocyte responsiveness
to endogenous and exogenous antigens, leading to
suppression of the immune response. An overall immune
response may be a consequence of a balance between helper
T lymphocyte and suppressor T lymphocyte stimulation.
Suppressor T cells are also significant in the establishment
of immunologic tolerance and are particularly active in
response to unprocessed antigen. The inability to confirm
the presence of receptor molecules on suppressor cells has
cast a cloud over the suppressor cell; however, functional
suppressor cell effects are indisputable. Some suppressor
T lymphocytes are antigen-specific and important in the
regulation of T helper cell function. Like cytotoxic T cells,
T suppressor cells are major histocompatibility complex
(MHC) class I-restricted. T cells may act as suppressors of
various immune responses by forming inhibitory cytokines.
supratypic antigen
Refer to public antigen.
suramin
Antrypol, 8,8′-(carbonyl-bis-(imino-3,1phenylenecarbonylimino))-bis-1,3,5-naphthalene
trisulfonic
acid; a therapeutic agent for African sleeping sickness
produced by trypanosomes. Of immunologic interest is its
ability to combine with C3b, thereby blocking binding of
factors H and I. The drug also blocks complement-mediated
lysis by preventing attachment of the membrane attack
complex of complement to the membranes of cells.
surface antigen
Epitopes on a cell surface such as the bacterial antigens Vi
and O.
surface immunoglobulin
All immunoglobulin isotypes may be expressed on the surfaces
of individual B cells but only one isotype is expressed
at any one time, with the exception of unstimulated mature
B lymphocytes that coexpress surface IgM (sIgM) and
surface IgD (sIgD). Refer to B lymphocyte receptor.
Immunize
(Inactive Tumor)
Challenge
(Live Tumor)
Result
SV40 (1)
SV40 (1)
No growth
SV40.
surface marker
A protein on a cell surface that reveals a cell type or stage
of differentiation.
surface phagocytosis
Facilitation of phagocytosis when microorganisms become
attached to the surfaces of tissues, blood clots, or leukocytes.
surface plasmon resonance (SRP)
A phenomenon that is the basis for instruments designed
to measure macromolecular interactions in real time. It
measures alterations in the refractive index of a medium
surrounding a receptor immobilized on a solid support that
occur when a ligand binds. SRP is useful in the analysis
of antigen–antibody interactions and can be employed to
determine kinetic parameters (association–dissociation
rate constants) and equilibrium binding constants and also
measure concentrations, perform epitope mapping, and
determine antibody isotypes.
surface secretions
Lysozyme induces lysis of bacterial cells by breaking
the linkage connecting N-acetyl muraminic acid and
N-acetylglucosamine in the walls of Gram-positive bacterial
cells. Lactoferrin interrupts metabolism of bacterial iron.
surrogate light chains (SLC)
Invariant light chains that are structurally homologous to
κ and λ light chains and associate with pre-B cell μ heavy
chains. They are the same in all B cells. V regions are absent
in surrogate light chains. Low levels of cell surface μ chain
and surrogate light chain complexes are believed to participate
in stimulation of κ or λ light chain synthesis and maturation
of B cells. This complex of two non-rearranging polypeptide
chains (V pre-B and λ5) synthesized by pro-B cells associate
with the Igμ heavy chain to form the pre-B cell receptor.
Sustiva
A human immunodeficiency virus 1 (HIV-1)-specific,
non-nucleoside, reverse transcriptase inhibitor. It is FDA
approved for the treatment of HIV. The mechanism of action
includes noncompetitive inhibition of HIV-1 reverse transcriptase
by efavirenz, the active component of the drug that
exerts no inhibitory effect on HIV-2 reverse transcriptase.
SV40 (simian virus 40)
An oncogenic polyoma virus. It multiplies in cultures of
rhesus monkey kidney and produces cytopathic alterations
SV40 (1)
SV40 (2)
No growth
SV40 (1)
Murine leukemia
virus (MuLV)
Murine leukemia
virus (MuLV)
Growth