Two alternate strategies for innate immunity to Epstein-Barr virus: One using NK cells and the other NK cells and ?d T cells.
journal of experimental medicine
2017; 214 (6): 1827-1841
The Intergenic Recombinant HLA-B*46:01 Has a Distinctive Peptidome that Includes KIR2DL3 Ligands.
2017; 19 (7): 1394-1405
Most humans become infected with Epstein-Barr virus (EBV), which then persists for life. Infrequently, EBV infection causes infectious mononucleosis (IM) or Burkitt lymphoma (BL). Type I EBV infection, particularly type I BL, stimulates strong responses of innate immune cells. Humans respond to EBV in two alternative ways. Of 24 individuals studied, 13 made strong NK and γδ T cell responses, whereas 11 made feeble γδ T cell responses but stronger NK cell responses. The difference does not correlate with sex, HLA type, or previous exposure to EBV or cytomegalovirus. Cohorts of EBV(+) children and pediatric IM patients include both group 1 individuals, with high numbers of γδ T cells, and group 2 individuals, with low numbers. The even balance of groups 1 and 2 in the human population points to both forms of innate immune response to EBV having benefit for human survival. Correlating these distinctive responses with the progress of EBV infection might facilitate the management of EBV-mediated disease.
View details for DOI 10.1084/jem.20161017
View details for PubMedID 28468758
Class I HLA haplotypes form two schools that educate NK cells in different ways.
2016; 1 (3)
HLA-B(∗)46:01 was formed by an intergenic mini-conversion, between HLA-B(∗)15:01 and HLA-C(∗)01:02, in Southeast Asia during the last 50,000 years, and it has since become the most common HLA-B allele in the region. A functional effect of the mini-conversion was introduction of the C1 epitope into HLA-B(∗)46:01, making it an exceptional HLA-B allotype that is recognized by the C1-specific natural killer (NK) cell receptor KIR2DL3. High-resolution mass spectrometry showed that HLA-B(∗)46:01 has a low-diversity peptidome that is distinct from those of its parents. A minority (21%) of HLA-B(∗)46:01 peptides, with common C-terminal characteristics, form ligands for KIR2DL3. The HLA-B(∗)46:01 peptidome is predicted to be enriched for peptide antigens derived from Mycobacterium leprae. Overall, the results indicate that the distinctive peptidome and functions of HLA-B(∗)46:01 provide carriers with resistance to leprosy, which drove its rapid rise in frequency in Southeast Asia.
View details for DOI 10.1016/j.celrep.2017.04.059
View details for PubMedID 28514659
Natural killer (NK) cells are lymphocytes having vital functions in innate and adaptive immunity, as well as placental reproduction. Controlling education and functional activity of human NK cells are various receptors that recognize HLA class I on the surface of tissue cells. Epitopes of polymorphic HLA-A,-B and -C are recognized by equally diverse killer cell immunoglobulin-like receptors (KIR). In addition, a peptide cleaved from the leader sequence of HLA-A,-B or -C must bind to HLA-E for it to become a ligand for the conserved CD94:NKG2A receptor. Methionine/threonine dimorphism at position -21 of the leader sequence divides HLA-B allotypes into a majority having -21T that do not supply HLA-E binding peptides and a minority having -21M, that do. Genetic analysis of human populations worldwide shows how haplotypes with -21M HLA-B rarely encode the KIR ligands: Bw4(+)HLA-B and C2(+)HLA-C KIR. Thus there are two fundamental forms of HLA haplotype: one preferentially supplying CD94:NKG2A ligands, the other preferentially supplying KIR ligands. -21 HLA-B dimorphism divides the human population into three groups: M/M, M/T and T/T. Mass cytometry and assays of immune function, shows how M/M and M/T individuals have CD94:NKG2A(+) NK cells which are better educated, phenotypically more diverse and functionally more potent than those in T/T individuals. Fundamental new insights are given to genetic control of NK cell immunity and the evolution that has limited the number of NK cell receptor ligands encoded by an HLA haplotype. These finding suggest new ways to dissect the numerous clinical associations with HLA class I.
View details for PubMedID 27868107