Relationship between CD4 T cell turnover, cellular differentiation and HIV persistence during ART

The precise role of CD4 T cell turnover in maintaining HIV persistence during antiretroviral therapy (ART) has not yet been well characterized. In resting CD4 T cell subpopulations from 24 HIV-infected ART-suppressed and 6 HIV-uninfected individuals, we directly measured cellular turnover by heavy water labeling, HIV reservoir size by integrated HIV-DNA (intDNA) and cell-associated HIV-RNA (caRNA), and HIV reservoir clonality by proviral integration site sequencing. Compared to HIV-negatives, ART-suppressed individuals had similar fractional replacement rates in all subpopulations, but lower absolute proliferation rates of all subpopulations other than effector memory (TEM) cells, and lower plasma IL-7 levels (p = 0.0004). Median CD4 T cell half-lives decreased with cell differentiation from naïve to TEM cells (3 years to 3 months, p<0.001). TEM had the fastest replacement rates, were most highly enriched for intDNA and caRNA, and contained the most clonal proviral expansion. Clonal proviruses detected in less mature subpopulations were more expanded in TEM, suggesting that they were maintained through cell differentiation. Earlier ART initiation was associated with lower levels of intDNA, caRNA and fractional replacement rates. In conclusion, circulating integrated HIV proviruses appear to be maintained both by slow turnover of immature CD4 subpopulations, and by clonal expansion as well as cell differentiation into effector cells with faster replacement rates

Quantification of T-cell and B-cell replication history in aging, immunodeficiency, and newborn screening

Quantification of T-cell receptor excision circles (TRECs) has impacted on human T-cell research, but interpretations on T-cell replication have been limited due to the lack of a genomic coding joint. We here overcome this limitation with multiplex TRG rearrangement quantification (detecting ∼0.98 alleles per TCRαβ+ T cell) and the HSB-2 cell line with a retrovirally introduced TREC construct. We uncovered 10 cell divisions in effector memory T-cell subsets. Furthermore, we show that TREC dilution with age in healthy adults results mainly from increased T cell replication history. This proliferation was significantly increased in patients with predominantly antibody deficiency. Finally, Guthrie cards of neonates with Down syndrome have fewer T and B cells than controls, with similar T-cell and slightly higher B-cell replication. Thus, combined analysis of TRG coding joints and TREC signal joints can be utilized to quantify in vivo T-cell replication, and has direct applications for research into aging, immunodeficiency, and newborn screening

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Major histocompatibility complex genes influence the outcome of HIV infection

Several alleles at multiple HLA loci have been found to be associated with infection with human immunodeficiency virus (HIV): HLA A1; B8, B35; Cw7, Cw4; DR1, DR3 and DQ1, are associated with particular disease manifestations and/or disease progression. Furthermore, in a pilot study we have shown an increase in the frequency of C4 null alleles and suggested that all the reported HLA alleles could reflect association with a limited number of ancestral haplotypes (AHs). On this occasion, we studied 122 Caucasoid patients classified according to Centers for Disease Control (CDC) criteria. The control group consisted of 67 seronegative homosexual or bisexual males at risk of developing HIV infection. C4 null alleles were unequivocally present in 58% of patients in CDC IV compared with 33% of the seronegative subjects (x2 = 5.65, p < 0.05). Furthermore, C4 null alleles could be excluded in only 8% and 16% of CDC III and IV, respectively, but in 30% of the seronegative subjects. An increased frequency of three AHs largely accounted for the increases in C4 null and HLA alleles. To examine the role of specific AHs we undertook a longitudinal analysis of a subgroup of 26 patients who seroconverted under observation. Seventeen of these patients were followed for 32 to 63 months. All seven patients with the 8.1 AH (A1, CW7, B8, BfS, C4AQ0, C4B1, DR3, DQ2) developed low CD4 lymphocyte counts (<450 × 106/l) compared with only 2 of 10 patients without this haplotype (p < 0.002). All three deaths occurred in patients with the 8.1 AH. The acquired immunodeficiency syndrome developed in three further cases with either 8.1- or B35- bearing (35.x) haplotypes. Sequential CD4/8 ratios showed an early and progressive decline in individuals with 8.1 or 35.x. Since the 8.1 and 35.x AHs contain deletions of the central major histocompatibility complex (MHC) genes, we suggest that the genes affecting HIV infection and progression are within the central MHC region

The development of immunodeficiency in patients chronically infected by HIV is influenced by specific MHC ancestral haplotypes containing C4 null alleles

No abstract availabl

MHC genes and HIV infection

Letter to the edito

Cytokine profiling in abacavir hypersensitivity patients

BACKGROUND: Abacavir hypersensitivity in genetically susceptible individuals implicates an abacavir-specific T-cell response to either the parent drug or a metabolite generated in vivo. We have analysed the cytokine profile in antigen-presenting cells and the T-lymphocytes that are involved in the pathological immune response to abacavir. METHODS: In this study, we compared abacavir-specific cytokine responses in cultured peripheral blood mononuclear cells (PBMCs) from HIV-infected abacavir hypersensitive, tolerant and naive individuals. Cells were cultured in the presence or absence of abacavir. Cytokine expression was determined by microarray analysis, enzyme-linked immunosorbent assays and flow cytometry. RESULTS: We demonstrated using in vitro models of immune activation that the production of interferon-gamma was specifically induced by abacavir treatment in PBMCs obtained from hypersensitive patients carrying the HLA-B*5701 allele (median 123.86 compared with -30.83 for tolerant controls, P=0.001). CONCLUSION: These results provide further insight into the immunological and metabolic basis of abacavir hypersensitivity syndrome. In vitro assays could assist in the identification of susceptible loci by providing a surrogate marker for the hypersensitivity reaction. Such a marker could be studied in unexposed individuals to shed further light on the immunopathogenesis of the abacavir hypersensitivity syndrome

MHC ancestral haplotypes containing HLA-B8 and B35 are associated with different patters of HIV-1 disease progression and complications

We have determined the effect of MHC genes on the survival of a cohort of 450 HIV infected subjects followed between 1983 and 1992. Among 130 patients whose seroconversion time was known, haplotypes bearing B8 or B35 conferred increased risk for early HIV-1 related death compared to those without these haplotypes [relative hazard 2.5 and 8.1, p=0.03 and 0.0001 respectively]. HLA B8 and the 8.1 ancestral haplotype [A1, B8, C4AQO, C481, BfS, DR3, DQ2] acted early in the disease and was associated with rapid early loss of CD4 cells [p=0.004 log rank test, median time to CD4 less than 20% 19 months compared to 58 months in non HLA B8s] but did not affect survival after the CD4 T cells count fell below 20% [p=0.39, median survival=55 months compared to 46 months in non HLA B8s]. Analysis of the phenotypes for the presence of parts of the 8.1 Ancestral Haplotype mapped the effect to the central MHC between HLA-B and complement C4, a region known to contain the TNF gene family. In contrast the haplotypes carrying B35 were found to effect B35 were found to effect survival in seroconverters by markedly reducing late survival. Early loss of CD4 cells was no greater in those with B35 than in those without this antigen [p=0.83]. Survival was reduced after the CD4 cell count had fallen below 20% [p=0.003, median survival =42 months compared to 74 months in non HLA B35s]. Several late complications of HIV-1 infection accounted for this difference, including an increase CD4 adjusted risk for cryptococcal meningitis [RH=3.1, p=0.017] and HIV encephalopathy [RH=2.1, p=0.03]. Disseminated MAC infection was also more frequent in these subjects [CD4 adjusted RH=2.9, p=0.002], such that the estimated probability of MAC infection in individuals with HLA B35 approached 100% as the CD4 count fell below 10 x 10(6)/L. In Cox proportional hazards survival models the effect of the 8.1AH was completely lost when CD4 T cells were included in the model but the influence of haplotypes containing HLA B35 was independent of blood CD4 cells or serum IgA levels. These data suggest the 8.1AH acts early in HIV-1 by affecting the rate of loss of CD4 cells, but the B35 containing haplotypes are associated with reduced survival as a result of a late CD4 independent effect predisposing to infection by intracellular pathogens