availability of synthetic drugs such as
zoledronate, pamidronate and
phosphoantigen BrHPP (Bromohydrin
Pyrophosphate) etc that selectively
activate γδ T cells has allowed for γδ T
cells to be used for clinical trials.
Role in humans
Immunoregulation
Infectious disease
HIV
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IL- 4, IL-5, IL-13 and IL-17 against extracellular pathogens
TNF and IFN-γ are involved in acting against viruses and intracellular pathogens
Cancer
IFN-γ, IL-6 and GM-CSF are implicated in tumour-induced inflammation
Cancer Immunotherapy
recognise and migrate to tumour sites their and attack
tumours
autoimmune/hypersensitivity
IL-4 and IL-13 are involved
in asthma and allergy
reactions
Subsets
Vδ1
spleen, thymus,dermin, liver and gut epitelia
predomintate during fetl
and early life in PB,
minotrity in adults
Vγ9Vδ2 most abundant
peripheral blood
Tnaive
TCM Central memmory
TEM Effector memmory
TEMRA
IL-17 producers
Vδ3
liver and gut epithelia
expression of the V regionn of the gd TCR chians
Background
Gamma/delta T cells form a unique subset of CD3+ T
lymphocytes expressing structurally distinct γδ
heterodimers as their antigen receptors
under 10 % of the total T cell count in the body
both innate effector functions and adaptive
immune response
cause antibody dependant cell
mediated cytotoxicity (ADCC) via
the FC γRIII (CD16) receptors
followed by rapid secretion of
cytokines and chemokines
respond to
phosphoantigens (of
microbial origin) and are
activated to proliferate and
carry out their immune
effector functions
Once activated cause
present antigens to
CD4+ and CD8+ cells
activated by low
molecular non peptide
phosphoantigens
IPP, HMBPP
secrete cytolytic factors such as granzymes and
perforins, along with chemokines (eg.
Lymphotactin, RANTES) and immunomodulatory
cytokines such as TNF, IFN-γ, IL-4, IL-5, IL-6,
IL-17, IL-13, IL-22, and GM-CSF
against invading pathogens or endogenous stress.
γδ T cell arise from DN2 and DN3 stage
receptors similar to
those found on
NK cells
involved in tissue repair and
epithelial cell regeneration