Chapter 1: The Immune System
Cytokines - Figure 13
Figure abbreviations: APC, antigen-presenting cell; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; LAK, lymphokine-activated killer; M-CFS, macrophage colony-stimulating factor; MHC, major histocompatibility complex; NK, natural killer; Tc, T cytotoxic, TCR, T-cell receptor; TGF, transforming growth factor; TNF, tumour necrosis factor
Source: Singulex
CKs are low molecular weight proteins that play a key role in the induction and regulation of the immune response. (Fig 1.13)
Produced by a variety of cells, their actions are mediated through their receptive receptors; they exert autocrine, paracrine and endocrine effects.
CKs regulate the intensity and duration of both the innate and adaptive immune response.
Antigen processing and presentation - Figure 14
Source: Wahl M. Muscular Dystrophy Association - Quest Magazine 2008 (15);4.
The various individual facets of the immune response interact in a complex fashion to result in a coordinated response.
Following a rapid response by the cells of the innate system, the cells of the adaptive immune system recognise Ags, expanding and activating effectors.
APCs, present throughout the body, internalise and process Ags, displaying part of it on their surface bound to a class II MHC molecule. (Fig 1.14)
Antibody-mediated cytotoxicity - Figure 15
Source: Casadevall A, et al. Nat Rev Microbiol 2004;2:695-703
This way APCs carry cargos of foreign Ags to lymphoid organs, where they are recognised by Th cells that initiate the adaptive response.
All aspects of the adaptive response are initiated and controlled by T cells. They recruit immunological effector mechanisms by direct contact or through CKs.
Abs may cause direct cytotoxicity by activation of the complement cascade or by recruiting effector cells (NK, macrophages, etc.) that cause cell death. (Fig 1.15)
Revision Questions
- What are CKs and how do they exert their function?
- What is the role of APCs?
- Which mechanisms are employed by Abs to cause dysfunctional cell death?
