Allele-Independent Turnover of Human Leukocyte Antigen (HLA) Class Ia Molecules.

Major histocompatibility complex class I (MHCI) glycoproteins present cytosolic peptides to CD8+ T cells and regulate NK cell activity. Their heavy chains (HC) are expressed from up to three MHC gene loci (human leukocyte antigen [HLA]-A, -B, and -C in humans), whose extensive polymorphism maps predominantly to the antigen-binding groove, diversifying the bound peptide repertoire. Codominant expression of MHCI alleles is thus functionally critical, but how it is regulated is not fully understood.

The kinetics of donor HLA class I-specific antibody absorption following a combined split liver and kidney transplant.

Hyperacute rejection of a transplanted liver is rare even when the recipient has circulating donor-specific alloantibodies (DSA). There is also evidence that a transplanted liver may provide immunological protection for other organs transplanted from the same donor. We monitored the kinetics of circulating DSA in a highly sensitized recipient of a combined split liver and kidney transplant and demonstrated a reduction in antibody titres immediately after liver perfusion.

Association of the human leucocyte antigen region with susceptibility to Parkinson's disease.

Objective: The core pathology of Parkinson's disease (PD) is a loss of the dopaminergic neurons in the nigro-striatal pathway, but this is only part of a more widespread pathological process, the nature of which is unknown. Recent data suggest a possible role for inflammation in this disease process. The Human Leucocyte Antigen (HLA) region is one of the most important genetic susceptibility factors in many immune-mediated diseases but has not been extensively investigated in PD.

Predicting the immunogenicity of human leukocyte antigen class I alloantigens using structural epitope analysis determined by HLAMatchmaker.

Background: Human leukocyte antigen (HLA) matching strategies for kidney transplantation assign equal weighting to mismatches at a particular locus and take no account of variation in immunogenicity according to recipient HLA type. We examined the ability of intra- and interlocus analysis of amino-acid polymorphisms at continuous (triplet) and discontinuous positions (eplet) defined by the HLAMatchmaker program to predict alloantigen immunogenicity.

Methods: Sera from highly sensitized patients were screened for HLA class-I alloantibodies and mismatched combinations were analyzed using HLAMatchmaker to determine the number of triplet or extended-triplet and eplet mismatches.

PECAM-1 polymorphism affects monocyte adhesion to endothelial cells.

Background: Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) plays an important role in leukocyte-endothelial cell adhesion and transmigration. Single nucleotide polymorphisms of PECAM-1 encoding amino acid substitutions at positions 98 leucine/valine (L/V), 536 serine/asparagine (S/N), and 643 arginine/glycine (R/G) occur in strong genetic linkage resulting in two common haplotypes (LSR and VNG). These PECAM-1 polymorphisms are associated with graft-versus-host disease after hematopoietic stem cell transplantation and with cardiovascular disease, but whether they influence PECAM-1 function is unknown.

A second major histocompatibility complex susceptibility locus for multiple sclerosis.

Objective: Variation in the major histocompatibility complex (MHC) on chromosome 6p21 is known to influence susceptibility to multiple sclerosis with the strongest effect originating from the HLA-DRB1 gene in the class II region. The possibility that other genes in the MHC independently influence susceptibility to multiple sclerosis has been suggested but remains unconfirmed.

Methods: Using a combination of microsatellite, single nucleotide polymorphism, and human leukocyte antigen (HLA) typing, we screened the MHC in trio families looking for evidence of residual association above and beyond that attributable to the established DRB1*1501 risk haplotype.

Utility of HLAMatchmaker and single-antigen HLA-antibody detection beads for identification of acceptable mismatches in highly sensitized patients awaiting kidney transplantation.

Background: In highly sensitized patients (HSP) awaiting renal transplantation, accurate delineation of acceptable human leukocyte antigen (HLA) mismatches (AMM) aids identification of suitable crossmatch negative donors. Comparison of differences in polymorphic triplet amino acid sequences in antibody accessible regions of HLA may predict immunogenicity. We have examined the ability of the HLAMatchmaker computer algorithm to predict AMM determined by antibody screening using the full repertoire of single-antigen HLA-A and -B specificities.

Monitoring systemic donor lymphocyte macrochimerism to aid the diagnosis of graft-versus-host disease after liver transplantation.

Background: The diagnosis of graft-versus-host disease (GvHD) after liver transplantation can be difficult because early symptoms are often nonspecific. In this study, the presence of donor lymphocyte macrochimerism in recipient peripheral blood was examined as a diagnostic aid for GvHD after cadaveric donor liver transplantation.

Methods: Between 1996 and 2002, 33 liver transplant recipients with a clinical suspicion of GvHD (skin rash, diarrhea, pyrexia, pancytopenia, or anemia, without an obvious alternative cause) were investigated for peripheral blood donor lymphocyte macrochimerism.