Article

HLA and AIDS: a cautionary tale

Intramural Research Support Program, SAIC Frederick, National Cancer Institute-Frederick, Frederick, MD 21702-1201, USA
Trends in Molecular Medicine (Impact Factor: 10.11). 10/2001; 7(9):379-381. DOI: 10.1016/S1471-4914(01)02131-1
Source: PubMed

ABSTRACT The human major histocompatibility complex HLA has been implicated repeatedly as a regulator of the outcome of HIV exposure and infection. A new study of long-term survivors who naturally depress HIV-1 replication and avoid the signs of AIDS for years after infection suggests that homozygosity for a group of HLA-B locus alleles termed Bw4 confers resistance, ostensibly by regulating natural killer cell–ligand interactions. However, close inspection of the accumulated evidence raises some questions and urges validation of the potential Bw4 effects in additional studies.

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    • "The patients in which these HIV-1 escape mutants appear may progress to AIDS. The CTL escape mutants are selected by strong immunological pressure via HIV-1-specific CTLs [10], and the disease progression to AIDS is associated with HLA class I alleles [11] [12]. Therefore, the characterization of HIV-1 epitope-specific CTLs is important for understanding the pathogenesis of HIV and developing an AIDS vaccine. "
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    ABSTRACT: The identification of HIV-1 cytotoxic T lymphocyte (CTL) epitopes presented by each HLA allele and the characterization of their CTL responses are important for the study of pathogenesis of AIDS and the development of a vaccine against it. In the present study, we focused on identification and characterization of HIV-1 epitopes presented by HLA-B*5401, which is frequently found in the Asian population, because these epitopes have not yet been reported. We identified these epitopes by using 17-mer overlapping peptides derived from HIV-1 Gag, Pol, and Nef. Seven of these 17-mer peptides induced HLA-B*5401-restricted CD8+ T cell responses. Only five HLA-B*5401-restricted Pol- or Nef-specific CD8+ T cell responses were detected in the analysis using 11-mer overlapping peptides. Three Pol and two Nef optimal peptides were identified by further analysis using truncated peptides. These epitope-specific CTLs effectively killed HLA-B*5401-expressing target cells infected with HIV-1 recombinant vaccinia virus, indicating that these peptides were naturally processed by HLA-B*5401 in HIV-1-infected cells. These epitope-specific CD8+ T cells were elicited in more than 25% of chronically HIV-1-infected individuals carrying HLA-B*5401. Therefore, these epitopes should prove useful for studying the pathogenesis of AIDS in Asia and developing a vaccine against HIV-1.
    Microbes and Infection 07/2008; 10(7):764-72. DOI:10.1016/j.micinf.2008.04.006 · 2.73 Impact Factor
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    • "In addition, since HIV-1-specific CTLs are expected to suppress HIV-1 replication in vivo, characterization of these epitopes is also necessary for studies aimed at developing HIV-1 vaccines and immunotherapy to induce HIV-1-specific CTLs, either of which might be expected to prevent HIV-1 infection and the progression to AIDS. HLA-A * 26 is one of the alleles associated with a slow progression to AIDS [12]. Therefore, identification and characterization of HIV-1-specific epitopes presented by this allele are necessary for studies on the immunopathogenesis of AIDS and vaccine development. "
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    ABSTRACT: It is speculated that HLA-A( *)26-restricted HIV-1-specific CTLs can control HIV-1, since HLA-A( *)26 is associated with a slow progression to AIDS. In three major HLA-A( *)26 subtypes, HLA-A( *)2601-restricted, and HLA-A( *)2603-restricted HIV-1 epitopes have been identified, but HLA-A( *)2602-restricted ones have not. We here identified HLA-A( *)2602-restricted HIV-1 epitopes by using reverse immunogenetics and compared the immunodominance of the epitopes among the three subtypes. Out of 110 HIV-1 peptides carrying HLA-A( *)26 anchor residues, only the Gag169-177 peptide, which had been previously identified as an HLA-A( *)2601- and HLA-A( *)2603-restricted immunodominant epitope, induced Gag169-177-specific CD8(+) T cells from only two of six HLA-A( *)2602(+) HIV-1-infected individuals. No difference in affinity of this epitope peptide was found among these three HLA-A( *)26 subtypes, indicating that Gag169-177 was effectively presented by HLA-A( *)2602 but recognized as a subdominant epitope in HIV-1-infected HLA-A( *)2602(+) individuals. These findings indicate different immunodominance of Gag169-177 epitope among 3 HLA-A( *)26 subtypes.
    Biochemical and Biophysical Research Communications 03/2008; 366(3):612-6. DOI:10.1016/j.bbrc.2007.11.031 · 2.28 Impact Factor
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    • "Since HIV infects immune cells to produce proliferation, spread and CD4+ T lymphocyte damage, the HLA alleles could influence the time from infection to AIDS progression [21]. For example, HLA-Cw4, a ligand for KIR 2DL1 influences the time to develop AIDS, [22]. These findings could have been due to genes in random association with HLA-B and C alleles such as TNF [17]. "
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    ABSTRACT: HIV infection and its outcome is complex because there is great heterogeneity not only in clinical presentation, incomplete clinical information of markers of immunodeficiency and in measurements of viral loads. Also, there many gene variants that control not only viral replication but immune responses to the virus; it has been difficult to study the role of the many AIDS restricting genes (ARGs) because their influence vary depending on the ethnicity of the populations studies and because the cost to follow infected individuals for many years. Nevertheless, at least genes of the major histocompatibility locus (MHC) such as HLA alleles have been informative to classify infected individuals following HIV infection; progression to AIDS and long-term-non-progressors (LTNP). For example, progressors could be defined as up to 5 years, up to 11 years or as we describe in this report up to 15 years from infection, and LTNP could be individuals with normal CD4+ T cell counts for more than 15 years with or without high viral loads. In this review, we emphasized that in the studies of ARGs the HLA alleles are important in LTNP; HLA-B alleles influencing the advantage to pathogens to produce immune defense mediated by CD8+ T cells (cognate immunuity). Our main point we make in this report is that contrary to recent reports claiming that this dominant effect was unlikely due to differences in NK activation through ligands such as HLA-Bw4 motif, we believe that cognate immunity as well as innate immunity conferred by NK cells are involved. The main problem is that HLA-Bw4 alleles can be classified according the aminoacid in position 80. Isoleucine determines LTNP, which is a ligand for 3DS1. Such alleles did not include HLA-B*44. B*13 and B*27 which have threonine at that position. The authors have not considered the fact that in addition to the NK immunoglobulin receptors, NK receptors can be of the lectin like such as NKG2A/HLA-E to influence the HIV infection outcome. HLA-Bw4 as well as HLA-Bw6 alleles can be classified into those with threonine or methionine in the second position of their leader peptides. These leader peptides are ligands for NKG2A in which methionine influences the inhibitory role of NKG2A for killing infected targets. Functional studies have not been done as well as studies of these receptors in infected individuals. However, analyses of the leader peptides of HLA-B alleles in published reports, suggested that threonine in the second position can explain the importance of HLA-B*57, B*13, B*44 as well as certain Bw6 alleles in LNTP. In addition, we analyzed the San Francisco database that was reported and found that the association of HLA-B alleles with LNTP or with progressors can be due to the presence of threonine or methionine in their second position. Therefore, studies of outcome of HIV infection should include not only mechanisms of cognate immunity mediated by peptides and CD8+ T cells but also, NK receptors of two types, NKG2A as well as 3DSI. We propose that the SCID mouse should be used to understand mechanisms mediated by many of the ARGs especially the importance of thymus derived cells as well as NK receptor interactions with their ligands in this experimental animal transplanted with human stem cells, thymus or NK cells obtained from individuals of known HLA genotypes.
    Journal of stem cells 02/2007; 2(4):237-248.
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