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314 Introduction to the Immune System
Barton F. Haynes / Kelly A. Soderberg / Anthony S. Fauci

	Figure 314-1  Overview of major TLR signaling pathways. All TLRs signal through MyD88, with the exception of TLR3. TLR4 and the TLR2 subfamily (TLR1, TLR2, TLR6) also engage TIRAP. TLR3 signals through TRIF. TRIF is also used in conjunction with TRAM in the TLR4–MyD88-independent...
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	Figure 314-2  Schematic model of intercellular interactions of adaptive immune system cells. In this figure, the arrows denote that cells develop from precursor cells or produce cytokines or antibodies; lines ending with bars indicate suppressive intercellular interactions. Stem cells...
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	Figure 314-3  CD4+ helper T1 (TH1) cells and TH2 T cells secrete distinct but overlapping sets of cytokines. TH1 CD4+ cells are frequently activated in immune and inflammatory reactions against intracellular bacteria or viruses, while TH2 CD4+ cells are...
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	Figure 314-4  Encounters between NK cells: potential targets and possible outcomes. The amount of activating and inhibitory receptors on the NK cells and the amount of ligands on the target cell, as well as the qualitative differences in the signals transduced, determine the extent of the NK...
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	Figure 314-5  The four pathways and the effector mechanisms of the complement system. Dashed arrows indicate the functions of pathway components. (After Morley and Walport; with permission. Copyright Academic Press, London, 2000.)
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	Figure 314-6  Development stages of T and B cells. Elements of the developing T and B cell receptor for antigen are shown schematically. The classification into the various stages of B cell development is primarily defined by rearrangement of the immunoglobulin (Ig), heavy (H), and light (L)...
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	Figure 314-7  Signaling through the T cell receptor. Activation signals are mediated via immunoreceptor tyrosine-based activation (ITAM) sequences in LAT and CD3 chains (blue bars) that bind to enzymes and transduce activation signals to the nucleus via the indicated intracellular activation...
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	Figure 314-8  B cell receptor (BCR) activation results in the sequential activation of protein tyrosine kinases, which results in the formation of a signaling complex and activation of downstream pathways as shown. Whereas SLP76 is recruited to the membrane through GADS and LAT, the mechanism...
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	Figure 314-9  Increased epithelial permeability may be important in the development of chronic gut T cell–mediated inflammation. CD4 T cells activated by gut antigens in Peyer's patches migrate to the LP. In healthy individuals, these cells die by apoptosis. Increased epithelial permeability may...
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	Figure 314-10  Pathways of Cellular Apoptosis. There are two major pathways of apoptosis: the death-receptor pathway, which is mediated by activation of death receptors, and the BCL2-regulated mitochondrial pathway, which is mediated by noxious stimuli that ultimately lead to mitochondrial...
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	Figure 314-11  Key migration steps of immune cells at sites of inflammation. Inflammation due to tissue damage or infection induces the release of cytokines (not shown) and inflammatory chemoattractants (red arrowheads) from distressed stromal cells and "professional" sentinels, such as mast...
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