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12 Cards in this Set

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Th1 type cells
Predominant role in inflammation

Cytokines produced: IL-2, IL-3, INF-gamma

Induction by: IL-12 and IFN-gamma

Differentiation promoted by transcription factor T-bet

Cross-regulation: IFN-gamma inhibits Th2 type responses
Th2 type cells
Predominant role in humoral responses

Cytokines produced: IL-3, IL-4, IL-10, IL-5 (helminth)

Growth promoted by IL-4

Differentiation promoted by transcription factor GATA-3

Cross-regulation: IL-4 promotes Th2 type responses at the expense of Th1 type responses and IL-10 inhibits Th1 type responses
Th17 type cells
Recruitment of neutrophils and monocytes, mediators of inflammation

Cytokines produced: IL-17 and IL-23

Differentiation promoted by IL-6, IL-1, IL-23, and TGFbeta

Cross regulation: not present with IL-4 and IFN-gamma

Involved in animal models of MS, inflammatory bowel disease, and rheumatoid arthritis
Regulatory T cells
Produce IL-10 or TGFbeta (transforming growth factor beta)
CD8+ effector cell actions
Cytotoxic potential
- Perforin
- Granzyme B

Cytokine production
- IFN-gamma
- TNF-alpha
- IL-17 (attracts neutrophils to a site of inflammation)
- IL-4 (seen in regulatory CD8+ T cells)
IL-2
Growth factor for helper T cells and for B cells
IL-4
Produced by Th2 type cells. It is a growth factor for Th2 cells and B cells and promotes differentiation of B cells to IgG1 and IgE production.
IFN-gamma
Produced by Th1 type cells. It is an enhancer of MHC class II expression for APC and promotes differentiation of B cells to some IgG production.
Isotype maturation
Switching of isotype from IgM production to IgG, IgE or IgA production (germinal centers and T cell development)

CD40L binding required (see hyper IgM syndrome)

Cytokine differentiation signals:
- IL-4 promotes IgE production, which is important for protection in helminth infections
- IFN-gamma promotes production of certain of the IgG subclasses, in particular those subclasses that enhance phagocytosis by promoting binding to FcR on the phagocytes
Isotype switching
Occurs at the gene level by a process referred to as 'switch recombination' in which the cell's already rearranged VDJ segment is brought adjacent to a constant region downstream of it's existing constant region and the intervening sequence is deleted. This process applies to both its membrane bound immunoglobulin (in the BCR) and to its secreted antibody.
Affinity maturation
Selection of cells bearing antigen receptors with the highest affinities for antigen when antigen is limiting

Occurs in germinal centers and is T cell dependent

'Somatic hypermutation' is important for this process
Somatic hypermutation
Occurs in rapidly dividing B cells in the germinal center and results in a high incidence of point mutations in the immunoglobulin genes, increasing or decreasing the strength of its binding to the stimulating antigen