8th Page Flashcards
What are the ways of killing by cytotoxic T cells?
- Apoptosis (through intracellular signaling)
- Release the contents of granules that damage the cell
Granzyme B
Activate a nuclease that destroys the target cell DNA.
Perforin
Pore-forming proteins that polymerize in the presence of Calcium and form channels in the target cell membrane.
CD2
Involved in T cell activation (Rosette formation).
CD3
Found on all T cells; associated with T-cell antigen receptor.
CD4
Identifies T helper cells; also found on most T regulatory cells.
CD4?
Co-receptor for MHC Class I.
CD10?
Protease; marker for pre-B CALLA
CD19?
Part of B-cell coreceptor; regulates B-cell development and activation.
CD21?
Receptor for complement component C3d; part of B-cell coreceptor with CD19.
CD23?
Regulation of IgE synthesis; triggers release of GM-CSF from monocytes.
CD25?
Receptor for IL-2.
CD44?
Adhesion molecule mediating homing to peripheral lymphoid organs.
CD45R?
Essential in T and B cell antigen-stimulated activation.
CD50?
Function: Cell adhesion and signaling.
CD94
Function: Subunit of NKG2-A complex involved in inhibition of NK cell cytotoxicity.
Function: Positive or negative modulation of T and B cell receptor signaling
CD5
Function: Identifies cytotoxic T cells
CD8
Function: Co-receptor for MHC Class I
CD8
Thymocytes, T cells, NK cells
CD2
Thymocytes, T cells
CD3
T helper cells, monocytes, macrophages
CD4
Mature T cells, thymocytes, subset of B cells
CD5
B and T cell precursors, bone marrow stromal cells
CD10
Thymocyte subsets, cytotoxic T cells
CD8
B cells, follicular dendritic cells
CD19, CD21
Macrophages NK cells, neutrophils
CD16
B cells, follicular dendritic cells, monocytes
CD23
Activated T, B cells, monocytes
CD25
Most leukocytes
CD44
Different forms on all hematopoietic cells
CD45R
NK cells, subsets of T cells
CD56, CD94
Double negative T cells
lack CD4 and CD8 markers
Double negative T cells
actively proliferate in the outer cortex under the influence of IL-7
Double negative T cells
undergo rearrangement of the genes that code for the antigen receptor known as TCR
Double positive T cell
Express both CD4 and CD8
Positive selection in Double Positive T cell maturation
occurs in the thymic cortex
T cells must recognize foreign antigen in association with class I or class II MHC molecules, allowing only double-positive cells with functional TCR receptors to survive.
Positive selection in Double Positive T cell maturation
Helper or inducer cells
CD4+
Negative selection in Double Positive T cell maturation
occurs in the thymic medulla
eliminating T cells that react strongly with self-peptides presented by MHC molecules through apoptosis.
Negative selection in Double Positive T cell maturation
Medulla
Survivors of selection exhibit only one type of marker, either CD4 or CD8, and they migrate to?
CD4+ T cells
recognize antigens in MHC Class II
produces IFN-γ, IL-2, TNF-Beta
Th1
Responsible for activation of cytotoxic T lymphocytes and macrophages
Th1
helps B cells produce antibodies against extracellular pathogens.
Th2
Produces IL-4, IL-5, IL-10, and IL-13
Th2
Has a role in suppressing the immune response to self-antigens and preventing autoimmunity.
T reg
Possess the CD4 antigen and CD25
T reg
T cells exposed to antigen
Activated T cells
Expressed receptors for IL2, just as activated B cells
Activated T cells
What is the receptor for IL-2 in Activated T cell?
CD25+
What is the normal ratio of CD4+:CD8+ cells?
2:1
What is the CD4+:CD8+ cell ratio in HIV?
1:2
or
0.5:1
What is the CD4+ cell count in AIDS?
less than 200 cells/mm³.
