T Cell Development Flashcards
T cell The development
Pluripotential stem cell
lymphoid committed stem cell (CALLA)
Pre T cell (CD 2,3)
Pre cortical T cell CD 1 2 3
Cortical T cell CD 2348
Medullary T cell CD 2,3 4/8
Circulating virgin T cell
Small non cleaved T cell
Large non cleaved T cell
T immunoblast
T-cells are derived from ______ cells often simply called pre-T-cells
pre-thymic cells
The pre cortical T-cell is often identified by its expression of CD1 antigen. All T-cells form Pre T cell express CD2 and CD3
The cortical T-cells lose the expression of ____ antigen. So, they become ____negative.
CD1
As they lose this expression and retain that of CD2 and CD3, they gain the expression of other CD antigens such as_____.
Thus, the cortical T-cells are?
CD4 and CD8
CD1-, CD4+, CD8+, and CD2+ and CD3+
In addition to expressing these cluster of differentiation antigens, the cortical cells also express.
T-cell receptors
CD1 antigen is _______ T-cell specific.
Pre cortical T cell
The medullary T-cells are of two major types: CD4+/CD8- and CD4-/CD8+.
Those that are CD8+/CD4- are
The CD4+/CD8- cells are referred to as
Cytotoxic T cell 94/95% of T Cells
Helper T cells
There are three other subtypes of T-cells that could form in small proportion in circulation:
• T-delay-hypersensitivity cells
• T-suppressor cells
• T-natural killer cells
The difference between the surface membrane immunoglobulin and T-cell receptor is that whereas the surface membrane immunoglobulin can identify antigens expressed on microbial agent or any foreign antigen, the T-cell receptor can identify antigens that are complexed with MHC antigens. (HLA antigens are capable of complexing other antigens.)
Only antigens complexed with HLA antigens are recognized by T-cells receptors. We say that T-cell receptors is MHC antigen restricted.
The T cell mediates
Cellular immunity
By this we mean a T cell identifies a pathological cell and delivers cytolytic kill and the T cell exacted the kill
How does T cell escape the kill
Presence of CALCIRETICULIN
able to neutralize it’s cytolytic proteins
T cells cytolytic proteins are
Perforins
Caspaces
How does the T cell identify neo antigen on pathological cell
T cell receptor TCR
T cell receptor is the equivalence of
Surface membrane immunoglobulin
After antigenic stimulation what does the virgin T cell do
Travels to PARACORTEX of follicle of lymph node
To become
Small non cleaved
Large non cleaved
T immunoblast
The T immunoblast doesn’t mature what does it do instead?
The T immunoblast it accumulates effector molecules with which it is able to implement cytolytic function
Memory T cell
Virgin T cell that had previously undergo maturation to T immunoblast
T immunoblast can also undergo reversal of maturation to look like original virgin T cell from which it was derived.
Function of T delayed hypersensitivity cell
Gives helper signals to macrophages to support or enhance micro phage functions against chronic bacteria & fungal illnesses
T suppressor cells
Exist to limit immune hypersensitivity.
Individuals deficient in T suppressor tend to have
With example
Excessive immune reactions or auto immune diseases eg SLE
Systemic Lupus Erythromatosis
T Natural killer cells
Immunity against development of cancers
Callable if identifying neo antigens in cells undergoing mitotic changes and deliver cytolytic kill
CD 8+ cells
Aka cytotoxic T cell
cells given by nature as a major defence against viral infections
Cells in the human bodythat are infected by the viruses are identified and cytolytic kill
CD4 + cell aka
Function
They help other immune cells to function properly.
Offer helper functions to B cell, macrophages, CTL, T suppressor cell, TDHS, T NK cell
In it’s absence or deficiency no other immune cell functions properly
CD4+ cell are
The pivotal cell of immunity
Types of t helper cell and their functions
TH1: effector cell able to cytolyze other cells
TH2 : T regulatory cells (pivotal)
TH17
(Produces cytokine: interleukine 17)
Connection between HIV & T helper cell
T-helper cells all express :CD4 molecule: This molecule is the receptor which:HIV uses to infect human cell.
Any human.cell expressing CD 4 molecule uses its membrane Glycoprotein 120 to interact with the CD4 molecule such that the virus becomes anchored to the molecule membrane.
The virus is also able to fuse its own membrane with that of the CD4+ cell such that it becomes internalized into the cytoplasm of CD 4 positive cell by well understood mechanisms
Hiv eliminates T helper cells removing the pivotal cell of immunity such that the individual is now at a risk it
Chronic bacterial infection
Chronic fungal
Acute bacterial
Development of cancer
List and explain 4 goals of Antiretroval therapy
- Virologist goal
- Immunological goal
- Clinical goal
- Epidemiological goal
Virologic goal
Virus becomes undetectable in blood
Immune reconstruction
Cytopathic effects of virus on CD4+ T cell is lifted.
Bone marrow can form new ones
Clinical goal
Cessation of development of opportunistic illnesses
After immunity is reconstituted, increased disposition to bacteria fungal and cancer is lifted.
Epidemiological goal
The individual with HIV becomes in infectious to sex partners
For every 1 individual that is on effective antiretroviral therapy, 5-10 new infections have been prevented in general populace
