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specific immune response to extracellular bacteria 663 spectratyping
Opsonic–promote ingestion and killing by phagocytic
cells (IgG)
Block attachment (IgA)
Neutralize toxins
Agglutinate bacteria–may aid in clearing
Render motile organisms nonmotile
Abs only rarely affect metabolism or growth of bacteria
(Mycoplasma)
Abs, combining with antigens of the bacterial surface,
activate the complement cascade, thus inducing an
inflammatory response and bringing fresh phagocytes and
serum Abs into the site
Abs, combining with antigens of the bacterial surface,
activate the complement cascade, and through the final
sequences the membrane attack complex (MAC)
is formed involving C5b–C9
Antimicrobial actions of antibodies.
Specific immune response to extracellular bacteria.
smaller and fuses with phagosomes more quickly than does
the azurophil granule.
specific immune response to extracellular bacteria
Antibodies are the primary agents that protect the body
against extracellular bacteria. Microbial cell wall polysaccharides
serve as thymus-independent antigens that stimulate
specific immunoglobulin M (IgM) antibody responses.
Cytokine production may even permit switching from IgM
to IgG production. Protein antigens of extracellular bacteria
primarily stimulate active CD4 + T cells. Toxins of extracellular
bacteria may activate multiple CD4 + T lymphocytes.
A bacterial toxin that stimulates an entire family of T lymphocytes
that express products of a certain family of v beta T
lymphocyte receptor genes is referred to as a superantigen.
Immune stimulation of this type may lead to the production
of abundant quantities of cytokines that lead to pathologic
sequelae. The resistance mechanism against extracellular
Spleen.
bacteria regrettably may include two reactions that produce
tissue injury: acute inflammation and endotoxin shock. In
addition, late in the course of a bacterial infection, pathogenic
antibodies may appear. The multiple lymphocyte
clones stimulated by bacterial endotoxins or superantigens
may lead to the production of autoimmunity through overriding
specific T cell bypass mechanisms. Autoreactive
lymphocytes may also be activated during this process.
specific immunity
An immune state in which antibodies or specifically sensitized
or primed lymphocytes recognize an antigen and react
with it. By contrast, immunologically competent cells may
interact with antigens to produce specific immunosuppression
referred to as immunologic tolerance.
specificity
Recognition by an antibody or lymphocyte receptor of a
specific epitope in the presence of other epitopes for which
the antigen-binding site of the antibody or lymphoid cell
receptor is specific.
speckled pattern
A type of immunofluorescence produced when serum from
a patient with one of several connective tissue diseases is
placed in contact with the human epithelial cell line HEp-2
and “stained” with fluorochrome-labeled goat or rabbit
antisera against human immunoglobulin. The speckled
pattern of fluorescence occurs in mixed connective tissue
disease, lupus erythematosus, polymyositis, sicca syndrome,
Sjögren’s syndrome, drug-induced immune reactions, and
rheumatoid arthritis. It is the most frequent pattern and
shows the greatest variations of immunofluorescent nuclear
staining. The speckles are classified as (1) fine speckles
associated with anticentromere antibody; (2) coarse
speckles associated with antibodies against the nonhistone
nuclear proteins Scl-70, nRNP, La/SSB, and Sm; and (3)
large speckles that may be limited to 3 to 10 per nucleus,
are seen in undifferentiated connective tissue disease, and
represent IgM antibody against class H3 histones.
spectratyping
Selected types of DNA gene segments that give a repetitive
spacing of three nucleotides or one codon.
Red pulp
Marginal sinus
Mantle zone
Germinal center
White pulp
Marginal zone
S