Download 27 Immunology #2

Cell Mediated Immunity
Introduction
Cytokines
Components of Cell Mediated
Immunity
Cell Mediated Immunity
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Introduction
– Involves specialized lymphocytes call Tcells
– T-cells mature in thymus
– Response to intracellular viruses,
multicellular parasites, transplanted tissues
and cancer
Cell Mediated Immunity
Cytokines are chemical messengers
 Interleukins are cytokines that allow
leukocytes to communicate
 Interferons are cytokines that protect
against viruses
 Chemokines cause leukocytes to move
to site of infection
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Cell Mediated Immunity
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Components
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Helper T Cells (TH )
Cytotoxic T Cells (TC )
Delayed Hypersensitivity T Cells (TD)
Suppressor T Cells (TS)
Activated Macrophages
Natural Killer Cells
Cell Mediated Immunity
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Helper T Cells
– Activate B-cells
– Activate cytotoxic T cells
– Activate other helper T cells
Cell Mediated Immunity

Cytotoxic T Cells
– Used to attack intracellular pathogens
such as viruses, some bacteria,
multicellular parasites
– Attaches to target cell
– Releases protein perforin which pokes
holes in target cell inducing lysis
– T cells continue as long as antigen is
present
Cell Mediated Immunity

Delayed Hypersensitivity T Cells
– Involved in allergic reactions like response
to poison ivy and transplanted tissue
rejection
– Originally named because transfer of cell
transferred immunity to TB
– Probably a subpopulation TH cells and TC
cells
Cell Mediated Immunity

Suppressor T Cells
– Appears to regulate immune response
– Probably a subpopulation of helper cells
Cell Mediated Immunity
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Activated Macrophages
– Stimulated by ingestion antigens and
cytokines from helper T cells
– Acquire enhanced ability to digest via
phagocytosis virus infected cells and
intracellular bacteria infected cells
– Can be antigen presenting cells
Cell Mediated Immunity
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Nautral Killer Cells
– Kill virus infected cells, tumor cells and
large parasites
– Not immunologically specific like cytotoxic
T cells