Possible effects of non-HLA antibodies in common typing sera on HLA antigen frequency data in leukemia

Dual infection and recombination of Kaposi sarcoma herpesvirus revealed by whole-genome sequence analysis of effusion samples

Kaposi sarcoma herpesvirus (KSHV) is the etiological agent of three malignancies, Kaposi sarcoma (KS), primary effusion lymphoma (PEL) and KSHV-associated multicentric Castelman disease. KSHV infected patients may also have an interleukin six-related KSHV-associated inflammatory cytokine syndrome. KSHV-associated diseases occur in only a minority of chronically KSHV-infected individuals and often in the setting of immunosuppression. Mechanisms by which KSHV genomic variations and systemic co-infections may affect the pathogenic pathways potentially leading to these diseases have not been well characterized in vivo. To date, the majority of comparative genetic analyses of KSHV have been focused on a few regions scattered across the viral genome. We used next-generation sequencing techniques to investigate the taxonomic groupings of viruses from malignant effusion samples from fourteen participants with advanced KSHV-related malignancies, including twelve with PEL and two with KS and elevated KSHV viral load in effusions. The genomic diversity and evolutionary characteristics of nine isolated, near full-length KSHV genomes revealed extensive evidence of mosaic patterns across all these genomes. Further, our comprehensive NGS analysis allowed the identification of two distinct KSHV genome sequences in one individual, consistent with a dual infection. Overall, our results provide significant evidence for the contribution of KSHV phylogenomics to the origin of KSHV subtypes. This report points to a wider scope of studies to establish genome-wide patterns of sequence diversity and define the possible pathogenic role of sequence variations in KSHV-infected individuals.

Relationship between human leukocyte antigen alleles and risk of Kaposi's sarcoma in Cameroon

Several studies published to date report associations between human leukocyte antigen (HLA) alleles and different types of Kaposi's Sarcoma (KS). However, there is little concordance between the HLA alleles identified and the populations studied. To test whether HLA alleles associate with KS in a Cameroonian case-control study, we performed high-resolution HLA typing in KSHV seropositive individuals. Among HIV-positive individuals, carriers of HLA-B*14:01 were at a significantly higher risk of AIDS-KS (p = 0.033). For HIV-negative patients, a gene-wise comparison of allele frequencies identified the HLA-B (p = 0.008) and -DQA1 (p = 0.002) loci as possible risk factors for endemic KS. Our study provides additional understanding of genetic determinants of KS and their implications in disease pathogenesis. Further validation of these findings is needed to define the functional relevance of these associations.

HLA C associations with acute leukaemia

Frequencies of HLA A, B, C, and DR antigens were calculated in 1009 leukaemia patients, all of whom had been treated with bone-marrow transplantation and reported to the International Bone Marrow Transplant Registry. Cw3 (relative risk = 2 X 26, p = 0 X 00002) and Cw4 (relative risk = 2 X 18, p = 0 X 00003) were significantly associated with acute leukaemia (p values adjusted for multiple comparisons). Cw3 (relative risk = 2 X 97, p = 0 X 00002) and Cw4 (relative risk = 2 X 10, p = 0 X 004) were also significantly associated with acute lymphoblastic leukaemia and Cw4 was significantly associated with acute myelogenous leukaemia (relative risk = 2 X 39, p = 0 X 0003). The data suggest that Cw3 and Cw4 may be markers for leukaemia susceptibility genes, genes that code for low immune responsiveness to putative leukaemia viruses, or genes that regulate the response to chemotherapy and, therefore, the attainment of remission, since most of these patients underwent transplantation during remission.

Genetically appropriate expression of HLA and DR (IA) alloantigens on human melanoma cell lines

Studies of the expression of HLA and DR alloantigens on cultured human melanoma cells in comparison with those expressed on peripheral lymphocytes and B-cells derived from the same patients have shown that the HLA-A,B, and C locus antigens expressed on the cultured tumor cells were consistent with those expected from the typing of peripheral blood lymphocytes. One melanoma cell line failed to express all the HLA antigens expected from donor typing. All five of the lines tested also expressed DR antigens and in three instances these could be demonstrated to have genetically consistent allotypes. However, in preliminary studies stimulation of allogeneic lymphocytes by the DR positive melanoma cells could not be demonstrated.

Histocompatibility testing for clinical bone marrow transplantation and prospects for identification of donors other than HLA genotypically identical siblings

Clinical histocompatibility testing has now developed to a stage where it is possible to select related bone marrow donors for some patients, when HLA genotypically identical siblings are not available. The most common type of such donors are the HLA phenotypically or HLA-D phenotypically identical related donors. The HLA-D homozygous recipient offers special options, since these patients can potentially receive bone marrow transplants from any of the parents or from HLA-haploidentical siblings. The studies in SCID have demonstrated that HLA-D compatibility in spite of HLA-A or B incompatibilities can be tolerated and there is now accumulating evidence that even patients with aplastic anemia or acute leukemia can be successfully treated with such bone marrow grafts.