The role of mucosal-associated invariant T cells in visceral leishmaniasis.

Mucosal-associated invariant T (MAIT) cells are restricted by MR1 and are known to protect against bacterial and viral infections. Our understanding of the role of MAIT cells in parasitic infections, such as visceral leishmaniasis (VL) caused by protozoan parasites of , is limited. This study showed that in response to , human peripheral blood MAIT cells from children with leishmaniasis produced TNF and IFN-γ in an MR1-dependent manner.

MR1 encompasses at least six allele groups with coding region alterations.

Unlike classical HLA class I genes, MR1 is assumed to have limited polymorphic positions. We developed a MR1 specific PCR assay and sequenced 56 DNA samples from cells with a diverse set of HLA genotypes. In this relatively small panel we found six allele groups encoding for different MR1 proteins.

The murine CD94/NKG2 ligand, Qa-1, is a high-affinity, functional ligand for the CD8αα homodimer.

The immune co-receptor CD8 molecule (CD8) has two subunits, CD8α and CD8β, which can assemble into homo or heterodimers. Nonclassical (class-Ib) major histocompatibility complex (MHC) molecules (MHC-Ibs) have recently been identified as ligands for the CD8αα homodimer. This was demonstrated by the observation that histocompatibility 2, Q region locus 10 (H2-Q10) is a high-affinity ligand for CD8αα which also binds the MHC-Ib molecule H2-TL.

Casting a wider net: Immunosurveillance by nonclassical MHC molecules.

Most studies of T lymphocytes focus on recognition of classical major histocompatibility complex (MHC) class I or II molecules presenting oligopeptides, yet there are numerous variations and exceptions of biological significance based on recognition of a wide variety of nonclassical MHC molecules. These include αβ and γδ T cells that recognize different class Ib molecules (CD1, MR-1, HLA-E, G, F, et al.) that are nearly monomorphic within a given species.