chapter 9 -11 Flashcards
(49 cards)
naive T cells
lymphocytes that have never encountered their specific antigen and thus have never responded to it, as distinct from effector and memory cells
effector T cells
the T cells that perform the functions of an immune response, such as cell killing and cell activation, that clear the infectious agent from the body. There are several different subsets, each with a specific role in an immune response
cell mediated immunity
immunity to infection in which antigen-specific T cells play the main role. It is defined operationally as all adaptive immunity that cannot be transferred to a naive recipient by serum antibody.
memory T cells
lymphocytes that mediate immunological memory. They are more sensitive than naive lymphocytes to antigen and respond rapidly on reexposure to the antigen that originally induced them
priming
the first encounter with a given antigen, which generates the primary adaptive immune response
dendritic cells
bone marrow derived cells found in most tissues, including lymphoid tissues. There are two main functional subsets. Conventional DCs take up antigen in peripheral tissues, are activated by contact with pathogens, and travel to the peripheral lymphoid organs, where they are the most potent stimulators of T cell responses. Plasmacytoid DCs can also take up and present antigen, but their main function in an infection is to produce large amounts of the antiviral interferons as a result of pathogen recognition through receptors such as TLRs. Both these types of DCs are distinct from the follicular DCs that present antigen to B cells in lymphoid follicles.
clonal expansion
the proliferation of antigen specific lymphocytes in response to antigenic stimulation that precedes their differentiation into effector cells. It is an essential step in adaptive immunity, allowing rare antigen-specific to increase in number so that they can effectively combat the pathogen that elicited the response
diapedesis
the movement of blood cells, particulalry leukocytes, from the blood across blood vessel walls into tissues.
integrins
heterodimeric cell-surface proteins involved in cell-cell and cell-matrix interactions. They are important in adhesive interactions between lymphocytes and antigen-presenting cells and in lymphocyte and leukocyte adherence to blood vessel walls and migration into tissuesw
CD40 ligand
found on activated helper T cells, it is a co-stimulatory molecule whose interaction with CD40 on B cells is required for the proliferation and class switching of antigen activated naive B cells. CD40 is also found on DCs, and the CD40-CD40 ligand interaction signals to naive T cells
CD40
found on DCs and B cells, interacts with CD40 ligand on T cells to function as co-stimulatory
CD28
an activating receptor on T cells for the B7 co-stimulatory molecules present on specialized antigen-presenting cells such as DCs
B7.1/B7.2
cell surface proteins on specialized antigen-presenting cells such as DCs, which are the major co-stimulatory molecules for T cells. Bind to CD28 protein on T cells
IL-2
cytokine produced by activated naive T cells and essential for their further proliferation and differentiation. It is one of the key cytokines in the development of an adaptive immune response
CD8 cytotoxic T cells
T cells that carry the co-receptor CD8 and recognize antigens, for example viral antigens that are synthesized in the cytoplasm of a cell and become bound to MHC class I molecules. CD8 T cells differentiate into cytotoxic CD8 T cells
Regulatory T cells
effector T cells that inhibit T cell responses and are involved in controlling immune reactions and preventing autoimmunity. Several different subsets have been distinguished, notably the T cell lineage that is produced in the thymus, and the induced regulatory T cells that differentiate from naive CD4 T cells in the periphery in certain cytokine environments
IFN-gamma
a cytokine produced by CD4 Th1 cells, CD8 T cells, and NK cells. Its primary function is the activation of macrophages and it acts through a different receptor from that of the type I interferons.
IL-10
cytokine produced by regulatory T cells, which tends to suppress lymphocyte responses
TGF-Beta
cytokine that tends to promote differentiation of regulatory T cells, among other effects.
Immunological synapse
the highly organized interface that develops between a T cell and the target cell it is in contact with, formed by T cell receptors binding to antigen and cell-adhesion molecules binding to their counterparts on the two cells. Also known as the supramolecular adhesion complex
cytotoxins
proteins made by cytotoxic T cells and NK cells that participate in the killing of target cells. Perforins, granzymes, and granulysins are the major defined cytotoxins.
Fas ligand
membrane bound protein found on TNF cytokines, induces apoptosis on cells carrying Fas when Fas interacts with Fas ligand
perforin
a protein stored in the lytic granules of cytotoxic T cells and NK cells, which on release polymerizes to form pores in cell membrane through which other cytotoxic proteins enter the target cell
granzymes
serine proteases that are present in cytotoxic CD8 T cells and NK cells and are involved in inducing apoptosis in target cell
