Page 503 - Review of Medical Microbiology and Immunology ( PDFDrive )

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PART VII Immunology
492
APC (antigen-
presenting cell),
APC
e.g., macrophage
(immunogen)
or dendritic cell
Class II MHC
Antigen processing within macrophage;
protein
viral proteins cleaved into small peptides
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mebooksfree.com mebooksfree.com Viral epitope APC receptor Activation of helper T cell mebooksfree.com mebooksfree.com
Helper
T
CD4
cell
T-cell
for Ag (TCR)

IL-2 receptor TCR Helper Activation IgM monomer
T
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cell
IL-4, IL-5
IL-2
of B cell
Activation of
B cell
cytotoxic T cell
Cytotoxins
TCR
Viral
CD4
Virus
epitope
T cell
cell
TCR
Differentiation
Cell death TCR CD8 Plasma
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Class
I MHC
cell
Virus-
protein
infected
cell
cell
Memory Tc
cell
FIGURE 57–2
Overview of the process by which cell-mediated immunity and antibody-mediated immunity are induced by exposure to a
virus. Note that the figure shows a virus as the immunogen in the top left corner, but the same processes occur for other microbes, such as bac-
teria or fungi. IL, interleukin; MHC, major histocompatibility complex. (Reproduced with permission from Stites D, Terr A, Parslow T, eds. Basic &
Clinical Immunology. 9th ed. Originally published by Appleton & Lange. Copyright 1997 McGraw-Hill.)
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Figure 57–3 summarizes the human host defenses against
virus-infected cells and illustrates the close interaction of
by the antigen receptor (IgM) on the surface of the B cell.
various cells in mounting a coordinated attack against the
The interleukins, on the other hand, are not specific.
pathogen. The specificity of the response is provided by the
As depicted in Figure 57–3, B cells can perform two
antigen receptor (T-cell receptor [TCR]) on the surface of
important functions during the induction process: (1) they

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