During HIV infection, CD4+ CD38+ T-cells are the predominant circulating CD4+ subset whose HLA-DR positivity increases with disease progression and whose V beta repertoire is similar to that of CD4+ CD38- T-cells

Peripheral immunophenotyping reveals lymphocyte stimulation in healthy women living with hereditary breast and ovarian cancer syndrome

Germline pathogenic variants in BRCA1 and BRCA2 (gpath(BRCA1/2)) represent genetic susceptibility for hereditary breast and ovarian cancer syndrome. Tumor-immune interactions are key contributors to breast cancer pathogenesis. Although earlier studies confirmed pro-tumorigenic immunological alterations in breast cancer patients, data are lacking in healthy carriers of gpath(BRCA1/2). Peripheral blood mononuclear cells of 66 women with or without germline predisposition or breast cancer were studied with a mass cytometry panel that identified 4 immune subpopulations of altered frequencies between healthy controls and healthy gpath(BRCA1) carriers, while no difference was observed in healthy gpath(BRCA2) carriers compared to controls. Moreover, 3 (one IgD-CD27+CD95+ B cell subpopulation and two CD45RA-CCR7+CD38+ CD4+ T cell subpopulations) out of these 4 subpopulations were also elevated in triple-negative breast cancer patients compared to controls. Our results reveal an activated peripheral immune phenotype in healthy carriers of gpath(BRCA1) that needs to be further elucidated to be leveraged in risk-reducing strategies.

Metronidazole Treatment Failure and Persistent BV Lead to Increased Frequencies of Activated T- and Dendritic-Cell Subsets

Metronidazole (MDZ) treatment failure and bacterial vaginosis (BV) recurrence rates are high among African women. This cohort study identified genital immune parameters associated with treatment response by comparing vaginal microbiota and immune cell frequencies in endocervical cytobrushes obtained from 32 South African women with symptomatic BV pre- and post-metronidazole treatment. Cervical T- and dendritic-cell subsets were phenotyped using multiparameter flow cytometry and the composition of vaginal microbial communities was characterized using 16S rRNA gene sequencing. MDZ treatment led to a modest decrease in the relative abundance of BV-associated bacteria, but colonization with Lactobacillus species (other than L. iners) was rare. At 6 and 12 weeks, MDZ-treated women had a significant increase in the frequencies of CCR5+ CD4+ T cells and plasmacytoid dendritic cells compared to the pre-treatment timepoint. In addition, MDZ non-responders had significantly higher frequencies of activated CD4 T cells and monocytes compared to MDZ responders. We conclude that MDZ treatment failure was characterized by an increased expression of activated T- and dendritic-cell subsets that may enhance HIV susceptibility. These data suggest the need to further assess the long-term impact of MDZ treatment on mucosal immune response and the vaginal microbiota.

Impact of sub-optimal HIV viral control on activated T cells

OBJECTIVE

HIV viral load (VL) monitoring is generally conducted 6-12 monthly in low- and middle-income countries, risking relatively prolonged periods of poor viral control. We explored the effects of different levels of loss of viral control on immune reconstitution and activation.

DESIGN

Two hundred and eight participants starting protease inhibitor (PI)-based second-line therapy in the EARNEST trial (ISRCTN37737787) in Uganda and Zimbabwe were enrolled and CD38 + /HLA-DR + immunophenotyping performed (CD8-FITC/CD38-PE/CD3-PerCP/HLA-DR-APC; centrally gated) in real-time at 0, 12, 48, 96 and 144 weeks from randomization.

METHODS

VL was assayed retrospectively on samples collected every 12-16 weeks and classified as continuous suppression (<40 copies/ml throughout); suppression with transient blips; low-level rebound (two or more consecutive VL >40, <5000 copies/ml); high-level rebound/nonresponse (two or more consecutive VL >5000 copies/ml).

RESULTS

Immunophenotype reconstitution varied between that defined by numbers of cells and that defined by cell percentages. Furthermore, VL dynamics were associated with substantial differences in expression of CD4 + and CD8 + cell activation markers, with only individuals with high-level rebound/nonresponse (>5000 copies/ml) experiencing significantly greater activation and impaired reconstitution. There was little difference between participants who suppressed consistently and who exhibited transient blips or even low-level rebound by 144 weeks ( P  > 0.2 vs. suppressed consistently).

CONCLUSION

Detectable viral load below the threshold at which WHO guidelines recommend that treatment can be maintained without switching (1000 copies/ml) appear to have at most, small effects on reconstitution and activation, for patients taking a PI-based second-line regimen.

Immune aging in multiple sclerosis is characterized by abnormal CD4 T cell activation and increased frequencies of cytotoxic CD4 T cells with advancing age

BACKGROUND

Immunosenescence (ISC) describes age-related changes in immune-system composition and function. Multiple sclerosis (MS) is a lifelong inflammatory condition involving effector and regulatory T-cell imbalance, yet little is known about T-cell ISC in MS. We examined age-associated changes in circulating T cells in MS compared to normal controls (NC).

METHODS

Forty untreated MS (Mean Age 43·3, Range 18-72) and 49 NC (Mean Age 48·6, Range 20-84) without inflammatory conditions were included in cross-sectional design. T-cell subsets were phenotypically and functionally characterized using validated multiparametric flow cytometry. Their aging trajectories, and differences between MS and NC, were determined using linear mixed-effects models.

FINDINGS

MS patients demonstrated early and persistent redistribution of naïve and memory CD4 T-cell compartments. While most CD4 and CD8 T-cell aging trajectories were similar between groups, MS patients exhibited abnormal age-associated increases of activated (HLA-DR⁺CD38⁺; (P = 0·013) and cytotoxic CD4 T cells, particularly in patients >60 (EOMES: P < 0·001). Aging MS patients also failed to upregulate CTLA-4 expression on both CD4 (P = 0·014) and CD8 (P = 0·009) T cells, coupled with abnormal age-associated increases in frequencies of B cells expressing costimulatory molecules.

INTERPRETATION

While many aspects of T-cell aging in MS are conserved, the older MS patients harbour abnormally increased frequencies of CD4 T cells with activated and cytotoxic effector profiles. Age-related decreased expression of T-cell co-inhibitory receptor CTLA-4, and increased B-cell costimulatory molecule expression, may provide a mechanism that drives aberrant activation of effector CD4 T cells that have been implicated in progressive disease.

FUNDING

Stated in Acknowledgements section of manuscript.

Recent Thymus Emigrant CD4+ T Cells Predict HIV Disease Progression in Patients With Perinatally Acquired HIV

BACKGROUND

Robust immune restoration in human immunodeficiency virus (HIV)-positive patients is dependent on thymic function. However, few studies have investigated thymic function and its correlation with disease progression over time in HIV-positive patients.

METHODS

In this longitudinal prospective study, we followed 69 HIV-positive patients who were perinatally infected. Peripheral blood mononuclear cells were stained with monoclonal anti-CD4 and anti-CD31 and recent thymic emigrants (CD4+recently emigrated from the thymus (RTE), CD4+CD31+) quantified by flow cytometry. Statistical analysis used Wilcoxon rank sum test, Kruskal-Wallis, Spearman correlation, and Kaplan-Meier estimates; Cox regression models were performed for the longitudinal analysis.

RESULTS

Median age of HIV positive patients enrolled was 13 years (interquartile range [IQR], 8.6). CD4+RTE% decreased with age and was higher in females. Median CD4+RTE% was 53.5%, IQR, 22.9. CD4+RTE% was closely related to CD4+% and absolute counts but independent of viral load and CD8+CD38+%. Antiretroviral compliance as well as higher nadir CD4+% were associated with higher CD4+RTE%. Low CD4+RTE% predicted poor progression of VL and CD4+% over time.

CONCLUSIONS

CD4+RTE% predicts disease progression and may reflect history of disease in HIV-positive patients and adolescents. They are easy to measure in the clinical setting and may be helpful markers in guiding treatment decisions.

CD127 expression, exhaustion status and antigen specific proliferation predict sustained virologic response to IFN in HCV/HIV co-infected individuals

Hepatitis C virus (HCV) infection is a major cause of morbidity and mortality in the HIV co-infected population. Interferon-alpha (IFN-α) remains a major component of anti-HCV therapy despite its deleterious effects on the immune system. Furthermore, IFN-α was recently shown to diminish the size of the latent HIV reservoir. The objectives of this study were to monitor the impact of IFN-α on T cell phenotype and proliferation of HIV and HCV-specific T cells during IFN therapy, and to identify immune markers that can predict the response to IFN in HICV/HIV co-infected patients. We performed longitudinal analyses of T cell numbers, phenotype and function in co-infected patients undergoing IFN-α therapy with different outcomes including IFN-α non-responders (NR) (n = 9) and patients who achieved sustained virologic response (SVR) (n = 19). We examined the expression of activation (CD38, HLA-DR), functional (CD127) and exhaustion markers (PD1, Tim-3, CD160 and CD244) on total CD4 and CD8 T cells before, during and after therapy. In addition, we examined the HIV- and HCV-specific proliferative responses against HIV-p24 and HCV-NS3 proteins. Frequencies of CD127⁺ CD4 T cells were higher in SVR than in NR patients at baseline. An increase in CD127 expression on CD8 T cells was observed after IFN-α therapy in all patients. In addition, CD8 T cells from NR patients expressed a higher exhaustion status at baseline. Finally, SVR patients exhibited higher proliferative response against both HIV and HCV antigens at baseline. Altogether, SVR correlated with higher expression of CD127, lower T cell exhaustion status and better HIV and HCV proliferative responses at baseline. Such factors might be used as non-invasive methods to predict the success of IFN–based therapies in co-infected individuals.

CD4+ T cells from elite suppressors are more susceptible to HIV-1 but produce fewer virions than cells from chronic progressors

Elite suppressors/controllers (ES) are HIV-1-infected individuals who maintain stable CD4(+) T-cell counts and viral loads of <50 copies/mL without antiretroviral therapy. Research has predominantly focused on immune factors contributing to the control of viral replication in these patients. A more fundamental question, however, is whether there are differences in the nature of CD4(+) T-cell infection in ES compared with viremic patients. Here, we compare chronic progressor (CP), ES, and uninfected donors in terms of three aspects of CD4(+) T-cell infection: cellular susceptibility to infection, death of infected cells, and production of virus from infected cells. Using multiple methods of infection and both single-cycle and replication-competent virus, we show that unmanipulated CD4(+) T-cell populations from ES are actually more susceptible to HIV-1 infection than those populations from CP. Depletion of highly susceptible cells in CP may contribute to this difference. Using 7AAD and AnnexinV staining, we show that infected cells die more rapidly than uninfected cells, but the increased death of infected cells from CP and ES is proportional. Finally, using an assay for measuring virus production, we show that virus production by cells from CP is high compared with virus production by cells from ES or uninfected donors. This higher virus production is linked to cellular activation levels. These data identify fundamental differences in chronic infection of ES and CP that likely contribute to differential HIV-1 disease progression.

Identification of three immunologic correlates for HIV type 1 pathogenesis in youth

To evaluate the stability and heterogeneity of cytokine and chemokine profiles in 80 youth with and without HIV-1 infection, we tested plasma samples at repeated visits without antiretroviral therapy. Among nine analytes that were quantified using multiplexing assays, interleukin 10 (IL-10), IL-18, and soluble CD30 persistently showed a positive correlation with HIV-1 viral load (Spearman ρ = 0.40-0.59, p < 0.01 for all). A negative correlation with CD4(+) T cell counts (ρ = -0.40 to -0.60, p < 0.01 for all) was also persistent for the three analytes. Analyses restricted to 48 AIDS-free youth (96 visits) yielded similar findings, as did multivariable models in which race, sex, age, body mass index, and time interval between visits were treated as covariates. These relationships reflected two novel features observed for all three analytes. First, their presence in plasma was relatively stable between visits (ρ = 0.50-0.90, p < 0.03), regardless of HIV-1 infection status. Second, pairwise correlation was strong and persistent in HIV-1-seropositive youth (ρ = 0.40-0.59, p < 0.01), but not in HIV-1, seronegatives (p > 0.13). Additional analytes, especially eotaxin/CCL11 and SDF-1β/CXCL12, had no correlation with HIV-1-related outcomes despite their stability between visits. Overall, circulating IL-10, IL-18, and soluble CD30 could partially track unfavorable responses to HIV-1 infection in youth. These markers of persistent immune activation are individually and collectively indicative of HIV-1 pathogenesis.

Association of IL-4 589 C/T promoter and IL-4RalphaI50V receptor polymorphism with susceptibility to HIV-1 infection in North Indians

The clinical course and outcome of HIV-1 infection are highly variable among individuals. Interleukin 4 (IL-4) is a key T helper 2 cytokine with various immune-modulating functions including induction of immunoglobulin E (IgE) production in B cells, downregulation of CCR5 and upregulation of CXCR4, the main co-receptors for HIV. Our objective is to investigate whether single-nucleotide polymorphisms (SNPs) in the IL-4 promoter 589 C/T and IL-4 Ralpha I50V affect the susceptibility to HIV infection and its progression to AIDS in North Indian individuals. The study population consisted of 180 HIV-1 seropositive (HSP) stratified on the basis of disease severity (stage I, II, III), 50 HIV-1 exposed seronegative (HES), and 305 HIV-1 seronegative (HSN) individuals. The subjects were genotyped for IL-4 589 C/T promoter polymorphism and IL-4 Ralpha I50V by polymerase chain reaction restriction fragment length polymorphism. The results showed that IL-4 589 C/T was not associated with the risk of HIV infection and disease progression. However, the IL-4Ralpha I50 allele and genotype was significantly increased in HSP compared to HSN and HSP and was associated with risk of HIV infection. The frequency of IL-4Ralpha I50 allele in the HSP group was higher than in HSN (76.11 vs. 64.75%; P = 0.000; OR = 1.734) and HES (76.11% vs. 62.00%; P = 0.007; OR = 1.953). Homozygous IL-4Ralpha I50I genotype was significantly increased in HSP group compared with HSN (58.88% vs. 44.26%; P = 0.002; OR = 1.804) and HES (58.88% vs. 42.00%; P = 0.038; OR = 1.978). The present study for the first time suggests an association of IL-4Ralpha I50 allele with increased likelihood of HIV-1 infection in North Indian population. Further studies are required to confirm these findings and understand the effect of IL-4Ralpha polymorphism on the outcome of HIV-1 infection.

Cytokine and chemokine gene polymorphisms among ethnically diverse North Americans with HIV-1 infection

Twenty-four common single nucleotide polymorphisms (SNPs) in 10 cytokine and chemokine genes were defined in 579 North Americans at high risk of HIV-1 infection due to sexual behavior and injection drug use. Among the 3 major ethnic (African-American, Hispanic/Latino, and other) groups involved, HIV-1-seropositive individuals differed significantly from ethnically matched HIV-1-seronegative individuals (odds ratios = 2.13-4.82; P = 0.003-0.05) for several SNPs and haplotypes defined at the IL4, IL4R, IL6, IL10, CCL5 (RANTES), and CXCL12 (SDF1) loci. In addition, the homozygous IL4-590T/T genotype was associated with higher (+87-131 cells/microL) CD4 T-cell counts in HIV-1-infected and AIDS-free adolescents not receiving antiretroviral therapy (adjusted P = 0.004). No SNPs at IFNG, IL2, IL12B, TNF, or CCL2 (MCP1) showed any association with HIV-related outcomes. Additional typing for IL1A, IL1B, IL1R1, IL1RN, and TGFB1 SNPs also failed to demonstrate any influence on HIV-1 infection or virologic/immunologic control in more selected patient groups. Coupled with previous findings, our data suggest that heritable IL4 and IL10 variations may contribute to the acquisition or progression of HIV infection and that the effects of other targeted loci in the cytokine and chemokine system cannot be established unequivocally in the study populations.

Propagation of CD4+ T cells specific for HIV type 1 envelope gp120 from chronically HIV type 1-infected subjects

HIV-specific CD4+ T cell responses, in particular to the HIV envelope antigen gp120, are often undetectable in the peripheral blood of HIV-infected individuals. The failure to detect these cells poses a significant impediment to studying the T cell populations that are considered to be essential for controlling HIV infection and has led to speculation that these cells are entirely depleted during HIV infection. This study was designed to test whether gp120-specific CD4+ T cells exist in HIV-infected subjects and can be expanded from peripheral blood mononuclear cells by in vitro stimulation with the gp120 antigen, allowing better characterization of these cells. Although gp120-specific T cell responses were barely observed in patient cells ex vivo before antigenic stimulation, CD4+ T cells specific for gp120 were successfully propagated from the blood of each asymptomatic chronically HIV-infected subject studied. The dominant epitopes recognized by gp120-specific CD4+ T cells from these HIV-infected subjects were mapped to well-conserved sites in the C1 and C2 domains of gp120. Two CD4+ T cell lines recognizing these two regions were subsequently established. The CD4+ T cell lines proliferated and produced interferon gamma in response to the specific epitopes, and the responses were MHC class II restricted. These T cell lines also exhibited cross-reactivity with gp120 from T cell line-adapted HIV-1 strains IIIB and MN, as well as with gp120 from primary isolates SF33 (subtype B), CA1 (subtype A), and CA10 (subtype A/E). The data demonstrate that CD4+ T cells specific for gp120 are not entirely depleted from the peripheral blood of chronically HIV-infected subjects; these cells are present in low numbers but can be expanded after antigenic stimulation in vitro.

Replication of HIV-1 deleted Nef mutants in chronically immune activated human T cells

Lymphocytes (PBMC) obtained from blood of HIV-sera negative Ethiopian immigrants (ETH) were highly susceptible to HIV-1 infection in vitro with no need for stimulation by mitogens. As the HIV nef gene product has been shown to enhance viral replication in stimulated primary lymphocytes, we investigated in this work the role of Nef in viral replication in the ETH cells. Lymphocytes obtained from ETH individuals supported high replication of wild-type HIV-1 and low but significant replication level of the two deleted Nef mutants (encode truncated Nef proteins consisting only of either the first 35 or the first 86 amino acids of Nef). In contrast, no replication was observed in nonactivated cells obtained from non-ETH individuals. After activation of the PBMC from ETH individuals with PHA, replication of both wild-type strains and the two deleted Nef mutant viruses further increased. The CD4(+) T cells of ETH individuals exhibited elevated levels of the surface activation markers CD45RO and HLA-DR, compared with T cells derived from non-ETH group. Likewise, expression of the chemokine receptors CCR5 and CXCR4 on these cells was higher in the ETH group than in the non-ETH group. Replication of HIV-1 wild-type and the isogenic-deleted Nef mutants was significantly correlated with the proportion of ETH cells expressing CD45RO and the chemokine receptors. This study suggests that HIV-1 may respond differently to several activation states characteristic of T cells. One activation state, defined by chronically activated lymphocytes from ETH individuals, is permissive to the wild-type HIV-1 and, to a lesser degree, to the Nef mutants. Further activation of these cells by exogenous stimuli enhances replication of the virus. Our results support the notion that Nef enhances the basal level of T cell activation and consequently, viral replication.

Increased levels of activated subsets of CD4 T cells add to the prognostic value of low CD4 T cell counts in a cohort of HIV-infected drug users

OBJECTIVE

To identify subsets of CD4 T lymphocytes that can predict the development of AIDS and to assess whether increased levels of these cellular markers could provide additional independent prognostic information to the CD4 T cell count and plasma HIV-1-RNA levels.

DESIGN AND METHODS

In a prospective study, a cohort of 85 HIV-positive intravenous drug users [clinical categories of the CDC classification A (n = 48) and B (n = 37)] were followed for a period of 37+/-13 months. Memory and activated CD4 and CD8 T cells were quantitated by three-colour flow cytometry at baseline and expressed as a percentage of total CD4 and CD8 lymphocytes. Clinical evaluations were performed at 6 month intervals. The relationships between these lymphocyte subsets and progression to AIDS were studied using Kaplan-Meier plots and proportional hazards regression models.

RESULTS

After adjustment for the level of CD4 T cells and plasma HIV-1-RNA levels, the elevation in the subset CD4+CD38+DR+ was the marker within the functionally distinct subsets of CD4 T lymphocytes with additional prognostic value in bivariate Cox regression models. In multivariate models, increased percentages of CD4+CD38+DR+ T cells provided the strongest independent prognostic information for progression to AIDS (relative hazard, 1.07; P < 0.0001).

CONCLUSION

Our results suggest that high levels of CD4+CD38+HLA-DR+ T cells reflect the increasing degree of CD4 T cell activation during the progression of HIV infection, and could be used together with the CD4 T cell and HIV-RNA levels to evaluate more accurately the progressive cellular immune impairment associated with the risk of progression to AIDS.

Thyroid function in children with perinatal human immunodeficiency virus type 1 infection

OBJECTIVE

To study thyroid function in children with perinatal HIV-1 infection retrospectively and determine whether thyroid abnormalities are correlated with clinical condition, disease progression, immunological impairment, and viral load.

STUDY DESIGN AND SETTING

Total (TT4) and free (FT4) thyroxine, total (TT3) and free (FT3) triiodothyronine, reverse triiodothyronine (rT3), thyrotropin (TSH), thyroglobulin (TG), and thyroid binding globulin (TBG) were measured twice in 56 children with perinatal human immunodeficiency virus type 1 (HIV-1) infection. Median age at first determination was 13.5 (range: 0.03-127.0) months; median age at second determination was 66.2 (range 3.42-147.4) months. Antithyroglobulin, antimicrosomal, thyroid peroxidase, and thyrotropin receptor antibodies were also evaluated. Fifty-three healthy children were selected as controls.

RESULTS

TT3, TT4, FT4, and TG were significantly reduced and rT3, TBG, and TSH increased in children with HIV-1 infection when compared with controls. Thyroid dysfunction correlated with severe immunosuppression and high viral load early in life preceded the onset of the disease and worsened over time. Autoantibodies were negative in all children with HIV-1 infection in all determinations.

CONCLUSION

Thyroid abnormalities are observed early in the course of perinatal HIV-1 infection; thyroid dysfunction is particularly pronounced in children with severe immunosuppression and high viral load. Modifications of thyroid function precede worsening of clinical course in HIV-1 infected children.

Activation of CD8 T cells normalizes and correlates with the level of infectious provirus in tonsils during highly active antiretroviral therapy in early HIV-1 infection

OBJECTIVES

To study the effects of antiretroviral therapy on T cell activation in blood and tonsils from HIV-1 infected individuals in relation to CD4 cell count, plasma viremia, and infectious HIV-1 provirus.

DESIGN

A 48-week study of viral load and T cell subsets in blood and tonsils from 12 HIV-1-positive individuals with a mean CD4 cell number of 400 x 10(6) cells/l treated with a combination of zidovudine, lamivudine, and indinavir.

METHODS

Tonsil biopsies and blood samples were collected at regular intervals. Lymphocytes were phenotyped and quantified by three-color flow cytometry; infectious provirus was quantified by a limiting dilution assay. HIV-1-negative individuals were included as controls.

RESULTS

The fraction of tonsillar CD8 T cells expressing CD69, CD38, or HLA-DR in the patients with suppressed virus replication declined to levels comparable with that in controls by 48 weeks and showed a strong positive correlation with tonsillar infectious provirus and plasma viremia. The level of CD4 T cell activation was within normal range in tonsils throughout the study. The fraction of HLA-DR+ cells within CD4 and CD8 T cells in blood declined rapidly in parallel with plasma viremia but remained slightly higher compared with that in uninfected individuals.

CONCLUSION

Antiretroviral therapy normalizes tonsillar CD8 T cell activation in HIV-1-positive individuals in parallel with suppression of viral replication, indicating reduced CD8 cell turnover. Normal tonsillar CD4 T cell activation suggests limited CD4 cell turnover in early HIV infection. Activated CD8 T cells in lymphoid tissue is superior to that in blood as an immunological marker for the virological response to antiretroviral therapy.

Reduced naive and increased activated CD4 and CD8 cells in healthy adult Ethiopians compared with their Dutch counterparts

To assess possible differences in immune status, proportions and absolute numbers of subsets of CD4+ and CD8+ T cells were compared between HIV- healthy Ethiopians (n = 52) and HIV- Dutch (n = 60). Both proportions and absolute numbers of naive CD4+ and CD8+ T cells were found to be significantly reduced in HIV Ethiopians compared with HIV- Dutch subjects. Also, both proportions and absolute numbers of the effector CD8+ T cell population as well as the CD4+CD45RA-CD27- and CD8+CD45RA-CD27- T cell populations were increased in Ethiopians. Finally, both proportions and absolute numbers of CD4+ and CD8+ T cells expressing CD28 were significantly reduced in Ethiopians versus Dutch. In addition, the possible association between the described subsets and HIV status was studied by comparing the above 52 HIV- individuals with 32 HIV+ Ethiopians with CD4 counts > 200/microliter and/or no AIDS-defining conditions and 39 HIV+ Ethiopians with CD4 counts < 200/microliter or with AIDS-defining conditions. There was a gradual increase of activated CD4+ and CD8+ T cells, a decrease of CD8+ T cells expressing CD28 and a decrease of effector CD8+ T cells when moving from HIV- to AIDS. Furthermore, a decrease of naive CD8+ T cells and an increase of memory CD8+ T cells in AIDS patients were observed. These results suggest a generally and persistently activated immune system in HIV- Ethiopians. The potential consequences of this are discussed, in relation to HIV infection.

Effect of didanosine, stavudine, and hydroxyurea therapy on apoptosis in CD45RA+ and CD45RO+ T lymphocyte subpopulations

The effect of aggressive antiretroviral therapy on spontaneous apoptosis (AP) in CD4+ and CD8+ lymphocytes expressing CD45RO (memory cells) and CD45RA (naive cells) and their relationship to cellular activation and viral load were examined. Ten patients receiving simultaneous treatment with d4T, ddI, and HU were evaluated. Flow cytometric analysis showed significant levels of AP (measured by TUNEL assay) among memory and naive T cells and an enhanced expression of CD38 and HLA-DR activation markers. The percentage of apoptotic CD4+CD45RO+ and CD4+CD45RA+ cells decreased, respectively, from 34 +/- 3.3 and 29 +/- 3.6 prior to treatment to 20.5 +/- 4 and 22 +/- 3.8 at week 8 into therapy. The percentage of apoptotic CD8+CD45RO+ and CD8+CD45RA+ cells similarly decreased, respectively, from 20 +/- 2.5 and 24 +/- 3 prior to treatment to 14.5 +/- 2.7 and 16 +/- 3 at week 8 into treatment. The percentage of CD4+ cells expressing the activation markers CD38 and HLA-DR decreased from 27 +/- 6 to 13 +/- 2 and from 26 +/- 4 to 13.5 +/- 3, respectively. The percentage of CD8+ cells expressing either CD38 or HLA-DR fell from 22 +/- 3 to 10 +/- 2 for the former and from 39 +/- 5 to 22 +/- 4 for the latter. This was associated with a significant decrease in viral load (mean, 1.4 log10), and a decline in circulating plasma TNF-alpha and sIL-2R levels from 50.5 +/- 10 to 21 +/- 6 and 92.5 +/- 11 to 68 +/- 9, respectively. These data indicate that short-term therapy with ddI, d4T, and HU in combination diminished AP, immune activation, and partially restored naive and memory T cell subpopulations.

Different meaning of CD38 molecule expression on CD4+ and CD8+ cells of children perinatally infected with human immunodeficiency virus type 1 infection surviving longer than five years

We investigated the relationship between CD4+CD38+, CD4+HLA-DR+, CD8+CD38+, and CD8+HLA-DR+ cell proportions (HLA-DR = major histocompatibility complex class II) (determined by two-color immunofluorescence) and the clinical condition, IL-2 and IL-6 production, viral RNA copy numbers, and the eventual immunologic-virologic course in 25 children perinatally infected with HIV-1 surviving longer than 5 y [median age, 92 (range, 63-136) mo]. Twelve healthy age-matched children were studied as control subjects. HIV-1+ children had lower percentages and absolute numbers of CD4+CD38+, whereas the percentages of CD4+HLA-DR+ and the percentages and absolute numbers of CD8+CD38+ and CD8+HLA-DR+ cells were higher than that of control subjects. The absolute numbers of CD4+ and the percentages of CD4+CD38+, CD8+CD38+, and CD8+HLA-DR+ cells directly correlated, whereas the percentages of CD4+CD38+ and CD4+HLA-DR+ cells, the percentages of CD4+CD38+ and CD8+CD38+ cells, the CD8+ cell absolute numbers, and the percentages of CD8+CD38+ cells did not. Severe manifestations and immunologic deterioration occurred in children with low CD4+CD38+ cell percentages, whereas virologic worsening was associated with low CD8+CD38+ and CD8+HLA-DR+ cell percentages. IL-2 production directly correlated with percentages and absolute numbers of CD4+CD38+ and CD8+CD38+ cells. RNA copy numbers inversely correlated with CD4+CD38+, CD4+HLA-DR+, CD8+CD38+, and CD8+HLA-DR+ cell percentages. This suggests that CD38 molecule expression on both CD4+ and CD8+ cell subsets is a favorable marker in HIV-1+ children. Perhaps CD8+CD38+ subsets are activated cells, whereas CD4+CD38+ subsets are immature cells, possibly the host's attempt at CD4+ cell renewal.

Contribution of cohort studies in understanding HIV pathogenesis: introduction of the GRIV cohort and preliminary results

In the present paper we review studies performed on HIV-infected patients cohorts in order to understand AIDS disease development. The interplay between diverse factors such as the HIV envelope proteins, cellular co-receptors, the immune response with chemokines and cytokines production define the viral tropism, cytopathicity and progression of HIV disease. We present the trends of the research particularly in the domain concerning host genetics. In this context, we describe the GRIV cohort of fast and slow/non-progressors, and its use for understanding basic features of the yet unknown HIV pathogenesis mechanisms.