Nadir CD4+ T-cell count and numbers of CD28+ CD4+ T-cells predict functional responses to immunizations in chronic HIV-1 infection

OBJECTIVE: To ascertain whether delaying the initiation of highly active antiretroviral therapy (HAART) compromises functional immune reconstitution in HIV-1 infection in persons who regain 'normal' CD4 T-cell counts after suppressive antiretroviral therapies. DESIGN: Prospective open-label study carried out at two University-affiliated HIV-outpatient clinics in the USA. SUBJECTS AND METHODS: Response to immunization was used as a model for in vivo functional immune competence in 29 HIV-1 infected patients with CD4 T-cell counts > 450 x 106 cells/l and HIV-RNA < 400 copies/ml for > 12 months after HAART and nine HIV-1 seronegative controls. After immunization with tetanus toxoid, diphtheria-toxoid, and keyhole limpet hemocyanin, immune response scores (IRS) were calculated using postimmunization antibody concentrations, lymphocyte proliferation, and delayed-type hypersensitivity responses to vaccine antigens. RESULTS: Despite normal numbers of circulating CD4 T-cells, the CD4 T-cell nadir before HAART initiation predicted the immune response to immunization (rho = 0.5; P < 0.005) while current CD4 T-cell count did not. Likewise, CD4 T-lymphocyte expression of the co-stimulatory molecule CD28 was also an independent predictor of response to immunization (rho = 0.5; P < 0.005). CONCLUSIONS: Even among persons who controlled HIV replication and normalized CD4 T-cell counts with HAART, pretreatment CD4 T-cell count and numbers of circulating CD4+CD28+ T-cells at immunization, but not current CD4 T-cell count, predict the ability to respond to vaccination. Delaying the initiation of HAART in chronic HIV-1 infection results in impaired functional immune restoration despite normalization of circulating CD4 T-cell numbers.     

Clonal breadth of the HIV-1-specific T-cell receptor repertoire in vivo as determined by subtractive analysis

OBJECTIVE: Although the epitopic breadth of HIV-1-specific CD8 T lymphocyte (CTL) responses has been described, the T cell receptor (TCR) diversity of virus-specific cells remains poorly defined. DESIGN AND METHODS: To address this issue, we applied a novel technique for subtractive analysis of the HIV-1-specific CTL repertoire, combining specific deletion of peptide-specific cells by 5-fluorouracil with TCR spectratyping to identify clonal breadth of CTL recognizing individual peptides. RESULTS: Comprehensive analysis of an infected individual reveals that nine identified HIV-1-specific responses are comprised of at least 38 distinct T-cell clones (ranging from two to 10 distinct clones per epitope). CONCLUSION: Given the potentially crucial role of T-cell receptor breadth for viral recognition and avoidance of escape, this subepitopic analysis of CTL may offer an important measure of cellular immunity for pathogenesis and vaccine studies.     

Combination antiretroviral therapy results in a rapid increase in T cell receptor variable region beta repertoire diversity within CD45RA CD8 T cells in human immunodeficiency virus-infected children

Human immunodeficiency virus (HIV) type 1 disrupts the T cell receptor (TCR) variable region (V) beta repertoire in CD8 T cells by impairing thymic capacity and skewing postthymic cellular maturation. The TCR repertoire was examined using spectratyping of CDR3 length diversity within CD45RA and CD45RO CD8 T cells in HIV-infected and healthy children. In healthy children, CDR3 lengths displayed Gaussian distribution in both CD45RA and CD45RO subsets. Vbeta families in HIV-infected children displayed a large proportion of perturbations in both subsets. High virus load and advanced immunosuppression correlated with increased perturbations within CD45RA but not CD45RO CD8 T cells. After therapy and virus suppression, there was rapid reestablishment of Gaussian distributions in CD45RA cells. HIV-1-induced disruption of TCR diversity within CD45RA CD8 T cells correlates with disease progression. Suppression of viral replication by treatment results in the rapid correction of TCR diversity in this CD8 subset because of emergence of new T cells from the thymus.     

Relationship between the size of the human immunodeficiency virus type 1 (HIV-1) reservoir in peripheral blood CD4+ T cells and CD4+:CD8+ T cell ratios in aviremic HIV-1-infected individuals receiving long-term highly active antiretroviral therapy

It has been demonstrated that human immunodeficiency virus type 1 (HIV-1) replication persists in most infected individuals receiving highly active antiretroviral therapy (HAART). However, studies addressing the relationship between low levels of ongoing viral replication and immunologic parameters, such as the CD4+:CD8+ T cell ratio, in such individuals have been lacking. Here, a statistically significant inverse correlation is shown between the frequency of CD4+ T cells carrying HIV-1 proviral DNA and the CD4+:CD8+ T cell ratio in infected individuals receiving HAART and in whom plasma viremia had been suppressed below the limit of detection for prolonged periods of time. No correlation was found between the frequency of HIV-1-specific cytotoxic CD8+ T lymphocytes (CTLs) and the CD4+:CD8+ T cell ratios in those individuals. These data suggest that persistent, low-level, ongoing viral replication, although not sufficient to maintain HIV-1-specific CTL responses, may explain, in part, why normalization of the CD4+:CD8+ T cell ratio is not achieved in some infected individuals successfully treated with HAART.     

Initiation of antiretroviral therapy during primary HIV-1 infection induces rapid stabilization of the T-cell receptor beta chain repertoire and reduces the level of T-cell oligoclonality

Major T-cell receptor beta chain variable region (TCRBV) repertoire perturbations are temporally associated with the down-regulation of viremia during primary human immunodeficiency virus (HIV) infection and with oligoclonal expansion and clonal exhaustion of HIV-specific cytotoxic T lymphocytes (CTLs). To determine whether initiation of antiretroviral therapy (ART) or highly active antiretroviral therapy (HAART) during primary infection influences the dynamics of T-cell-mediated immune responses, the TCRBV repertoire was analyzed by semiquantitative polymerase chain reaction in serial blood samples obtained from 11 untreated and 11 ART-treated patients. Repertoire variations were evaluated longitudinally. Stabilization of the TCRBV repertoire was more consistently observed in treated as compared with untreated patients. Furthermore, the extent and the rapidity of stabilization were significantly different in treated versus untreated patients. TCRBV repertoire stabilization was positively correlated with the slope of HIV viremia in the treated group, suggesting an association between repertoire stabilization and virologic response to treatment. To test whether stabilization was associated with variations in the clonal complexity of T-cell populations, T-cell receptor (TCR) heteroduplex mobility shift assays (HMAs) were performed on sequential samples from 4 HAART-treated subjects. Densitometric analysis of HMA profiles showed a reduction in the number of TCR clonotypes in most TCRBV families and a significant decrease in the total number of clonotypes following 7 months of HAART. Furthermore, a biphasic decline in HIV-specific but not heterologous CTL clones was observed. This indicates that ART leads to a global reduction of CD8(+) T-cell oligoclonality and significantly modulates the mobilization of HIV-specific CTL during primary infection. (Blood. 2000;95:1743-1751)     

Effects of combination chemotherapy and highly active antiretroviral therapy on immune parameters in HIV-1 associated lymphoma

OBJECTIVE: To measure the effects of combined chemotherapy and highly active antiretroviral therapy (HAART) on immune cell counts and plasma HIV-1 RNA loads in patients with AIDS-related lymphoma (ARL) to determine the implications for opportunistic infection prophylaxis and medium-term immune function. DESIGN AND METHODS: Peripheral blood total lymphocyte count, CD4 T-cell count, CD8 T-cell count, CD19 B-cell count, CD16/CD56 natural killer cell count and plasma HIV-1 RNA load were prospectively measured at ARL diagnosis, at 1 and 3 months during and 1, 3 and 6 months after chemotherapy in twenty patients receiving HAART. RESULTS: Significant declines in T-helper cell (CD4) count, natural killer cell (CD16/CD56) and B lymphocyte count (CD19 cells) occurred during the first 3 months of chemotherapy. There was no significant alteration in the T-cytotoxic cell (CD8) count, CD4 percentage or HIV-1 RNA load during the study period. The T-helper cell and natural killer cell counts recovered to pre-treatment levels within 1 month of finishing chemotherapy. The recovery of B-cells was slower with pre-treatment levels only being achieved after 3 months. The recovery of CD4 T-cell count following completion of chemotherapy was more rapid than described for ARL patients who were not receiving concomitant HAART. CONCLUSIONS: By combining chemotherapy with HAART, immune function is better maintained in the medium term. The CD4 T-cell count falls by 50% during chemotherapy and this will help to identify patients who require opportunistic infection prophylaxis during chemotherapy.     

Distinct contributions of CD4(+) and CD8(+) naive and memory T-cell subsets to overall T-cell-receptor repertoire complexity following transplantation of T-cell-depleted CD34-selected hematopoietic progenitor cells from unrelated donors

Normalization of restricted T-cell-receptor (TCR) repertoire is critical following T-cell-depleted (TCD) stem cell transplantation. We present a prospective study analyzing respective contributions of naive and memory T-cell subsets within the CD4(+) and CD8(+) compartments to the evolution of overall TCR-repertoire complexity following transplantation of CD34-selected peripheral blood progenitor cells from unrelated donors. During the first year after transplantation, sorted CD4/45RA, CD4/45R0, CD8/45RA, and CD8/45R0 subsets were analyzed at 3-month intervals for TCR-repertoire complexity by CDR3 size spectratyping. Skew in TCR-repertoire was observed only in early memory-type T cells. CD4(+) and CD8(+) subsets differed in clonal distribution of CDR3 sizes, with rapid Gaussian normalization of bands in CD4/45R0(+) T cells. Naive T cells displayed normal repertoire complexity and contributed significantly to skew correction. Our data provide direct evidence for an important role of de novo maturation of naive T cells in normalization of an initially restricted TCR-repertoire following transplantation of CD34-selected, TCD-depleted peripheral blood progenitors from unrelated donors.     

Impact of 5 years of maximally successful highly active antiretroviral therapy on CD4 cell count and HIV-1 DNA level

OBJECTIVES: To evaluate the impact on CD4 cell count and HIV-1 DNA level in peripheral blood mononuclear cells (PBMC) of long-term highly active antiretroviral therapy (HAART) in the setting of maximal success, i.e., constant plasma HIV-1 RNA load suppression. DESIGN: Retrospective analysis of patients selected for a constantly undetectable plasma HIV-1 RNA load since HAART initiation. METHODS: HIV-1 DNA was measured in PBMC using a real-time polymerase chain reaction assay. Loess estimates and regression analysis were used for modelling the variations of the CD4 cell count and HIV DNA level over time. RESULTS: The study included 41 patients chronically infected with HIV-1 who had been taking HAART for a median duration of 60.4 months and had an undetectable plasma HIV RNA load ever since the first 6 months of HAART; 25 were tested for HIV-1 DNA. The mean CD4 cell count increase was high during the first 18 months on therapy (168 x 10 cells/l per year), much lower afterwards (38 x 10 cells/l per year), independently of the baseline CD4 cell count. Most of the patients (73.2%) reached a CD4 cell count constantly > or = 400 x 10/l during follow-up. HIV-1 DNA showed a mean decrease of 0.48 log10 copies/10 PBMC during the first year, of 0.18 log10 copies/10 PBMC per year during the 2nd and 3rd years, but no significant decrease afterwards. CONCLUSIONS: These results question the benefit of very long-term maintenance of HAART in terms of CD4 gain and HIV-1 DNA reduction.     

Diagnostic accuracy of CD4 cell count increase for virologic response after initiating highly active antiretroviral therapy

OBJECTIVE: To derive and internally validate a clinical prediction rule for virologic response based on CD4 cell count increase after initiation of HAART in a resource-limited setting. DESIGN AND METHODS: A retrospective cohort study at two HIV care clinics in Gaborone, Botswana. The participants were previously treatment-naive HIV-1-infected individuals initiating HAART. The main outcome measure was a plasma HIV-1 RNA level (viral load) < or = 400 copies/ml (i.e. undetectable) 6 months after initiating HAART. RESULTS: The ability of CD4 cell count increase to predict an undetectable viral load was significantly better in those with baseline CD4 cell counts < or = 100 cells/microl [area under the ROC curve (AUC), 0.78; 95% confidence interval (CI), 0.67-0.89; versus AUC, 0.60; 95% CI, 0.48-0.71; P = 0.018]. The sensitivity, specificity, and positive and negative predictive values of a CD4 cell count increase of > or = 50 cells/microl for an undetectable viral load in those with baseline CD4 cell counts < or = 100 cells/microl were 93.1, 61.3, 92.5 and 63.3%, respectively. Alternatively, these values were 47.8, 87.1, 95.0 and 24.5%, respectively, if a increase in CD4 cell count of > or = 150 cells/microl was used. CONCLUSIONS: CD4 cell count increase after initiating HAART has only moderate discriminative ability in identifying patients with an undetectable viral load, and the predictive ability is higher [corrected] in patients with lower baseline CD4 cell counts. Although HIV treatment programs in resource-constrained settings could consider the use of CD4 cell count increases to triage viral load testing, more accurate approaches to monitoring virologic failure are urgently needed.     

HIV-1感染者CD73~+CD8~+ T细胞减少与T细胞异常活化的相关性研究

目的探讨HIV-1感染者外周血CD8~+T细胞上CD73的表达特点及其与T细胞异常活化和疾病进展的关系。方法研究入选65例HIV-1感染者和27例健康对照。通过流式细胞术检测研究对象外周血CD73~+CD8~+T细胞的频率和绝对计数,并将患者CD73~+CD8~+T细胞绝对计数和频率与其CD4~+T细胞计数、HIV-1载量以及CD38~+CD8~+T细胞频率进行相关性分析。结果与健康对照相比,HIV-1感染者外周血CD73~+CD8~+T细胞绝对计数和频率均明显降低(P均0.05);HIV-1感染者外周血CD73~+CD8~+T细胞绝对计数和频率与CD4~+T细胞计数呈正相关(r=0.555,P=0.001;r=0.342,P=0.005),与CD38~+CD8~+T细胞频率呈负相关(r=-0.384,P=0.002;r=-0.387,P=0.001);HIV-1感染者CD73~+CD8~+T细胞的绝对计数与HIV-1载量呈弱负相关(r=-0.261,P=0.035)。结论 HIV-1感染者外周血CD73~+CD8~+T细胞的减少不但与患者T细胞的活化程度呈显著负相关,而且与AIDS疾病进展相关。     

Characteristics of HIV-1-infected patients with CD4:CD8 lymphocyte ratio normalization on antiretroviral therapy

Antiretroviral therapy for human immunodeficiency virus (HIV)-infection results in normalization of CD4:CD8 T-lymphocyte ratio in about 6% of cases. The T-cell ratio normalization on therapy was associated with a baseline CD4 of over 350 cells per microliter and a T-cell ratio of over 0.5 (for each, p < 0.01), but not with the current level of viral load suppression or compliance with clinic appointments (for each, p > 0.05). The patients with T-cell ratio normalization had a baseline median CD4 count of 428 cells per microliter (range, 353-883 cells per microliter) and a median T-cell ratio of 0.75 (range, 0.54-0.87). We could not address the effect of baseline viral load on T-cell ratio normalization, but there was no association with age, gender, race, HIV risk factor, or the length of antiretroviral therapy.     

Characterization of human cytomegalovirus peptide-specific CD8(+) T-cell repertoire diversity following in vitro restimulation by antigen-pulsed dendritic cells.

Under conditions of impaired T-cell immunity, human cytomegalovirus (HCMV) can reactivate from lifelong latency, resulting in potentially fatal disease. A crucial role for CD8(+) T cells has been demonstrated in control of viral replication, and high levels of HCMV-specific cytotoxic T-lymphocytes are seen in immunocompetent HCMV-seropositive individuals despite very low viral loads. Elucidation of the minimum portion of the anti-HCMV T-cell repertoire that is required to suppress viral replication requires further study of clonal composition. The ability of dendritic cells to take up and process exogenous viral antigen by constitutive macropinocytosis was used to study HCMV-specific T-cell memory in the absence of viral replication. The specificity and clonal composition of the CD8(+) T-cell responses were evaluated using HLA tetrameric complexes and T-cell receptor beta chain (TCRBV) spectratypic analyses. There was a skewed reactivity toward the matrix protein pp65, with up to 40-fold expansion of CD8(+) T cells directed toward a single peptide-MHC combination. Individual expansions detected on TCRBV spectratype analysis were HCMV-specific and composed of single or highly restricted numbers of clones. There was preferential TCRBV gene usage (BV6.1/6.2, BV8, and BV13 in HLA-A*0201(+) individuals) but lack of conservation of CDR3 length and junctional motifs between donors. While there was a spectrum of TCR repertoire diversity directed toward individual MHC-peptide combinations between donors, a relatively small number of clones appeared to predominate the response in each case. These data provide further insight into the range of anti-HCMV responses and will aid the design and monitoring of adoptive immunotherapy protocols.     

Long-term immunological response in HIV-1-infected subjects receiving potent antiretroviral therapy

OBJECTIVE: To determine the long-term T-lymphocyte response to highly active antiretroviral therapy (HAART) and to define predictors of the immunological response. DESIGN: Cohort study, including 135 HIV-1-infected subjects at a city general practice who commenced HAART between 1996 and 1998. METHODS: Collection of plasma HIV-1 RNA, CD4+ and CD8+ T-lymphocyte data at 3-6 monthly time intervals over 2 years. RESULTS: Seventy-three subjects (54%) achieved suppression of plasma HIV-1 RNA to levels below 400 copies/ml during the observation period, 31 individuals (23%) had detectable plasma HIV-1 RNA below 10,000 copies/ml and 31 subjects (23%) had virological failures with viral loads above 10,000 copies/mL. Median CD4+ T lymphocytes increased from 246 to 463 x 10(6) cells/l, showing a median rise of 20 x 10(6) cells/l per month in the first 3 months and 7 x 10(6) cells/l per month thereafter. The proportion of individuals who reached CD4+ cell counts above 500 x 10(6) cells/l increased from 8% at baseline to 54% at 2 years. Treatment-na?ve individuals, subjects with a large reduction of HIV-1 RNA or a large early CD8+ increase had better early CD4+ responses. Long-term CD4+ T-cell increases were inversely correlated with mean plasma HIV-1 RNA levels. Baseline CD4+ T-cell count was the most important determinant of reaching CD4+ cell counts above 500 x 10(6) cells/l. Nineteen per cent of subjects had no further CD4+ T-cell increases in the second year of therapy despite undetectable viral load. CONCLUSIONS: Immune reconstitution is a slow process, showing a large individual variability. The virological response to HAART was the most important determinant of the immunological short- and long-term response.     

Differences in HIV-2 plasma viral load and immune activation in HIV-1 and HIV-2 dually infected persons and those infected with HIV-2 only in Abidjan, Côte D'Ivoire

OBJECTIVE: To determine whether blood plasma levels of HIV-2 RNA viral loads and immune activation markers differ between persons infected with HIV-2 only and those dually infected with HIV-1 and HIV-2. METHODS: Between September 1996 and February 2000, we collected, analyzed and compared levels of HIV-2 RNA in plasma and immune activation markers among 52 persons infected with HIV-2 alone and 75 with confirmed dual infection. We also compared viral load and immune activation in patients who were infected with HIV-1 only and those who were dually infected. RESULTS: When we conducted a CD4 T-cell count-stratified multivariate analysis of HIV-2 viral load, controlling for difference in CD4 T-cell counts, age and sex: at < 200 x 10 CD4 T cells/l, HIV-2 viral load was 2.0 log10 copies/ml lower in dually infected patients than in HIV-2 only patients (P < 0.0001). At CD4 T-cell counts between 200 x 10 and 500 x 10/l, HIV-2 viral load was 0.3 log10 copies/ml lower in dually infected patients (P = 0.45). However, at CD4 T-cells counts > 500 x 10/l, HIV-2 viral load was 0.9 log10 copies/ml higher in dually infected patients (P < 0.0001). Dually infected persons with undetectable HIV-2 viral loads had significantly higher median levels of CD8 T cells expressing CD38 (P < 0.001) and HLA-DR (P = 0.01) than HIV-2 only infected patients. CONCLUSION: These results suggest that in dual infection, the level of HIV-2 replication depends on the immune status of the patients, with HIV-1 out-replicating HIV-2 as disease progress.     

HIV／AIDS患者血浆病毒载量及外周血T淋巴细胞亚群的变化

目的：观察国内HIV／AIDS患者血浆病毒载量和外周血CD4^ 、CD8^ T淋巴细胞的变化，探讨这些变化的临床意义。方法：选择未经抗病毒治疗的HIV／AIDS患者124例，用bDNA法检测血浆病毒载量，并用流式细胞仪检测外周血CD4^ 、CD8^ T淋巴细胞。结果：AIDS患者的血浆病毒载量明显高于HIV感染者，血浆病毒载量与CD4^ 细胞计数呈显著负相关，但其最高峰位于CD4^ 细胞计数100／μl处，然后随着CD4^ 细胞计数的下降而减少。CD4^ T细胞计数为AIDS组＜HIV组＜正常对照组：HIV感染者的CD8^ T细胞计数显著高于正常组和AIDS组，而AIDS患者CD8^ T细胞数则随着CD4^ T细胞减少而下降。结论：血浆病毒载量随着疾病进展而显著升高，但在疾病晚期则有所降低。外周血CD4^ T细胞计数随着疾病的进展而进行性减少；CD8^ T细胞计数在感染早期显著升高，进入晚期则减少。在评价HIV感染者和AIDS患者病情时，应结合病毒载量、CD4^ 、CD8^ T细胞计数综合分析。     

我国部分地区未治疗HIV感染人群的病毒载量趋势分析

目的了解中国艾滋病病毒（HIV）感染者体内病毒载量状况,及病毒载量与临床指征之间的相互关系;为中国艾滋病的预防和抗病毒研究提供基础数据。方法回顾性分析中国2003-2005年间检测的HIV感染者的病毒载量和CD4计数等数据,用SAS9.1进行统计分析,非参数检验。结果中国未治疗的HIV感染人群其病毒载量的最大浓度区域,2005年为10^4-10^5拷贝/ml,浓度从2003年的11.2%,2004年19.7%上升到2005年33.6%。中国未治疗的HIV感染人群的病毒载量随着CD4数的升高而减小,病毒载量的中位数,CD4〈200时为5.16lg/ml,CD4〉500时为2.77lg/ml（P〈0.0001）。未治疗组男性病人的病毒载量中位数为4.52lg/ml,高于女性的3.84lg/ml（P〈0.0005）,差异有统计学意义。结论病毒载量是监测HIV感染者的病程,评估抗病毒治疗的重要指标。中国未治疗的HIV感染人群的病毒载量呈现逐年上升的趋势,应尽早开展抗病毒治疗。     

Fluctuations of functionally distinct CD8+ T-cell clonotypes demonstrate flexibility of the HIV-specific TCR repertoire

T-cell receptor (TCR) diversity of virus-specific CD8+ T cells likely helps prevent escape mutations in chronic viral infections. To understand the dynamics of the virus-specific T cells in more detail, we followed the evolution of the TCR repertoire specific for a dominant HLA-B*08-restricted epitope in Nef (FLKEKGGL) in a cohort of subjects infected with HIV. Epitope-specific CD8+ T cells used structurally diverse TCR repertoires, with different TCRbeta variable regions and with high amino acid diversity within antigen recognition sites. In a longitudinal study, distinct Vbeta populations within the HIV-specific TCR repertoire expanded simultaneously with changes in plasma viremia, whereas other Vbeta populations remained stable or even decreased. Despite antigenic variation in some subjects, all subjects had the consensus sequence present during the study period. Functional analysis of distinct Vbeta populations revealed differences in HIV-specific IFN-gamma secretion ex vivo as well as differences in tetramer binding, indicating functional heterogeneity among these populations. This contrasts with findings in a subject on antiretroviral therapy with suppression of viremia to less than 50 copies/mL, where we observed long-term persistence of a single clonotype. Our findings illustrate the flexibility of a heterogeneous HIV-1-specific CD8+ TCR repertoire in subjects with partial control of viremia.     

Dysregulation of CD28 and CTLA-4 expression by CD4 T cells from previously immunodeficient HIV-infected patients with sustained virological responses to highly active antiretroviral therapy

OBJECTIVES: Current guidelines recommend commencing highly active antiretroviral therapy (HAART) in HIV-infected patients when CD4 T-cell counts reach 350 cells/microL. However, late-presenting HIV-infected patients with CD4 T-cell counts<50 cells/microL are still common. The ability of long-term HAART to normalize immune dysregulation in severely immunodeficient HIV-infected patients remains unclear. Here we address indices of immune dysregulation in previously severely immunocompromised HIV-infected patients treated with long-term HAART who had achieved increased CD4 T-cell counts and complete suppression of HIV viraemia. METHODS: We examined expression of CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and intracellular perforin by CD4 and CD8 lymphocytes from 25 highly selected HIV-infected patients [nadir CD4 T-cell counts <50 cells/microL, >4 years on HAART and >6 months of complete viral suppression (<50 HIV-1 RNA copies/mL)] and 18 HIV-seronegative age- and sex-matched controls. RESULTS: HIV-infected patients had lower percentages of CD28-expressing CD4 lymphocytes and higher percentages of CTLA-4-expressing CD4 lymphocytes than controls. The percentage of CTLA-4-expressing CD4 lymphocytes correlated inversely with that of CD28-expressing CD4 lymphocytes. The proportion of CD4 lymphocytes expressing perforin was generally low. However, more HIV-infected patients than controls had >1% of CD4 lymphocytes expressing perforin [11 of 25 (44%) vs. one of 18 (5.5%)]. The percentage of CD8 lymphocytes expressing perforin did not differ between HIV-infected patients and controls. Amongst HIV-infected patients, the percentage of perforin-expressing CD8 lymphocytes correlated inversely with nadir but not current CD4 T-cell count. CONCLUSIONS: Expression of CD28, CTLA-4 and perforin by CD4 lymphocytes remain dysregulated in HIV-infected patients with previous severe immunodeficiency, despite increased CD4 T-cell counts and control of HIV viraemia by HAART.