<P> Mucosal associated invariant T cells (MAITs) are a special type of T cell recognised since about 2009 . </P> <Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (February 2016) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (February 2016) </Td> </Tr> <P> Gamma delta T cells (γδ T cells) represent a small subset of T cells that possess a distinct T cell receptor (TCR) on their surfaces . A majority of T cells have a TCR composed of two glycoprotein chains called α - and β - TCR chains . However, in γδ T cells, the TCR is made up of one γ - chain and one δ - chain . This group of T cells is much less common in humans and mice (about 2% of total T cells); and are found mostly in the gut mucosa, within a population of lymphocytes known as intraepithelial lymphocytes . In rabbits, sheep, and chickens, the number of γδ T cells can be as high as 60% of total T cells . The antigenic molecules that activate γδ T cells are still widely unknown . However, γδ T cells are not MHC - restricted and seem to be able to recognize whole proteins rather than requiring peptides to be presented by MHC molecules on APCs . Some murine γδ T cells recognize MHC class IB molecules, though . Human Vγ9 / Vδ2 T cells, which constitute the major γδ T cell population in peripheral blood, are unique in that they specifically and rapidly respond to a set of nonpeptidic phosphorylated isoprenoid precursors, collectively named phosphoantigens, which are produced by virtually all living cells . The most common phosphoantigens from animal and human cells (including cancer cells) are isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMPP). Many microbes produce the highly active compound hydroxy - DMAPP (HMB - PP) and corresponding mononucleotide conjugates, in addition to IPP and DMAPP . Plant cells produce both types of phosphoantigens . Drugs activating human Vγ9 / Vδ2 T cells comprise synthetic phosphoantigens and aminobisphosphonates, which upregulate endogenous IPP / DMAPP . </P>

What is the difference between t cells and white blood cells