CD4/CD8 T-cell ratio predicts HIV infection in infants: the National Heart, Lung, and Blood Institute P2C2 Study

Trajectories of CD4 T-cell count, CD8 T-cell count, and CD4/CD8 ratio in patients with HIV and long-term virological suppression based on Yunnan HIV cohort

OBJECTIVE

Our objective was to evaluate the trajectory of immunology in patients with HIV with different baseline CD4 T-cell count strata after antiretroviral therapy (ART) under long-term viral suppression.

METHODS

This was a sub-analysis focused on patients with virological suppression for at least 5 years after ART. Data were obtained from the Yunnan HIV cohort in China. Patients were categorized according to prespecified baseline CD4 T-cell counts. The trajectories of CD4 T-cell count, CD8 T-cell count, and CD4/CD8 ratio changing over time were fitted using a B-spline regression model. The Cox proportional hazards regression model was used to assess the association of baseline CD4 T-cell count with the risk of both immunological responder (IR) and CD4/CD8 ratio normalization.

RESULTS

A total of 2618 patients with a median follow-up of 7.25 years (interquartile range [IQR] 5.92-8.75) were included. Over a period of 12 years, the mean CD4 T-cell count remained above 500 cells/μL in all groups. The mean CD4/CD8 ratio was solely normalized in patients whose baseline CD4 T-cell counts were above 350 cells/μL. Patients with higher baseline CD4 T-cell counts showed higher risks of both IR and CD4/CD8 ratio normalization than those with the lowest (all p trend <0.001). A higher baseline CD4 T-cell count predicted a shorter time for both IR and CD4/CD8 ratio normalization.

CONCLUSIONS

Long-term, sustained viral suppression may not be able to fully normalize immunological functions in patients with HIV. A high baseline CD4 T-cell count benefits IR and CD4/CD8 ratio normalization.

Performance Evaluation of Microscanner Plus, an Automated Image-Based Cell Counter, for Counting CD4+ T Lymphocytes in HIV Patients

Counting CD4+ T lymphocytes using flow cytometry is a standard method for monitoring patients with HIV infections. Simpler and cheaper alternatives to flow cytometry are in high demand because getting access to flow cytometers is difficult or impossible in resource-limited settings. We evaluated the performance of the Microscanner Plus, a simple and automated image-based cell counter, in determining CD4 counts against a flow cytometer. CD4 count results of the Microscanner Plus and flow cytometer were compared using samples from 47 HIV-infected patients and 87 healthy individuals. All CV% for precision and reproducibility tests were less than 10%. The Microscanner Plus's lowest detectable CD4 count was determined to be 15.27 cells/µL of whole blood samples. The correlation coefficient (R) between Microscanner Plus and flow cytometry for CD4 counting in 134 clinical samples was very high, at 0.9906 (p < 0.0001). The automated Microscanner Plus showed acceptable analytical performance for counting CD4+ T lymphocytes and may be particularly useful for monitoring HIV patients in resource-limited settings.

Predictors of CD4:CD8 ratio normalization and its effect on health outcomes in the era of combination antiretroviral therapy

Background

HIV leads to CD4:CD8 ratio inversion as immune dysregulation progresses. We examined the predictors of CD4:CD8 normalization after combination antiretroviral therapy (cART) and determined whether normalization is associated with reduced progression to AIDS-defining illnesses (ADI) and death.

Methods

A Canadian cohort of HIV-positive adults with CD4:CD8<1.2 prior to starting cART from 2000–2010 were analyzed. Predictors of (1) reaching a CD4:CD8 ≥1.2 on two separate follow-up visits >30 days apart, and (2) ADI and death from all causes were assessed using adjusted proportional hazards models.

Results

4206 patients were studied for a median of 2.77 years and 306 (7.2%) normalized their CD4:CD8 ratio. Factors associated with achieving a normal CD4:CD8 ratio were: baseline CD4+ T-cells >350 cells/mm³, baseline CD8+ T-cells <500 cells/mm³, time-updated HIV RNA suppression, and not reporting sex with other men as a risk factor. There were 213 ADIs and 214 deaths in 13476 person-years of follow-up. Achieving a normal CD4:CD8 ratio was not associated with time to ADI/death.

Conclusions

In our study, few individuals normalized their CD4:CD8 ratios within the first few years of initiating modern cART. This large study showed no additional short-term predictive value of the CD4:CD8 ratio for clinical outcomes after accounting for other risk factors including age and HIV RNA.

Quantitative MRI Measures in SIV-Infected Macaque Brains

Multiple MRI modalities including Diffusion Tensor Imaging (DTI), perfusion MRI, in vivo MR Spectroscopy (MRS), volumetric MRI, contrast-enhanced MRI, and functional MRI have demonstrated abnormalities of the structural and functional integrity as well as neurochemical alterations of the HIV-infected central nervous system (CNS). MRI has been proposed as a robust imaging approach for the characterization of the stage of progression in HIV infection. However, the interpretation of the MRI findings of HIV patients is complicated by the fact that these clinical studies cannot readily be controlled. Simian immunodeficiency virus (SIV) infected macaques exhibit neuropathological symptoms similar to those of HIV patients, and are an important model for studying the course of CNS infection, cognitive impairment, and neuropathology of HIV disease as well as treatment efficacy. MRI of non-human primates (NHPs) is of limited benefit on most clinical scanners operating at or below 1.5 Tesla because this low field strength does not produce high-quality images of the relatively small NHP brain. Contemporary high field MRI (3T or more) for clinical use provides impressive sensitivity for magnetic resonance signal detection and is now accessible in many imaging centers and hospitals, facilitating the use of various MRI techniques in NHP studies. In this article, several high field MRI techniques and applications in macaque models of neuroAIDS are reviewed and the relation between quantitative MRI measures and blood T-cell alterations is discussed.

CD4+ T-lymphocyte count/CD8+ T-lymphocyte count ratio: surrogate for HIV infection in infants?

INTRODUCTION

Early diagnosis and treatment is necessary to prevent HIV-infected infants progressing to AIDS. Antibody testing is not confirmatory before the age of 18 months and PCR not widely available in resource-poor settings. We studied the accuracy of CD4(+) T-lymphocyte count, CD4% and CD4/CD8 ratio as surrogate markers of infant HIV infection.

METHODS

Two hundred and fifty-eight HIV-exposed Indian infants at a median age of 5 months (range 1-18) had DNA PCR and CD4, CD8 counts performed.

RESULTS

Fifty five infants tested positive by HIV-1 DNA PCR whereas 203 were negative. Median CD4 count, CD4% and CD4/CD8 ratio were significantly lower in DNA PCR+ infants. Overall sensitivity and specificity of CD4/CD8 ratio <1.0 in predicting HIV was 91 and 92% with a negative predicted value (NPV) and positive predicted value (PPV) of 97 and 76%, respectively.

CONCLUSION

CD4/CD8 ratio <1.0 is a more sensitive surrogate marker of HIV infection in Indian infants than a CD4 count <1500 cells/µl or CD4% <25%.

The myocardium of fetuses with endocardial fibroelastosis contains fewer B and T lymphocytes than normal control myocardium

The observation that endocardial fibroelastosis (EFE) can result from an immune response to maternal autoantibody deposition in the fetal myocardium raises the possibility that the fetal immune system may contribute to the pathogenesis of idiopathic EFE and dilated cardiomyopathy (DCM). This study sought to characterize myocardial immune cell presence in fetuses and neonates with idiopathic EFE + DCM, in those with EFE + structural heart disease, and in normal control subjects. Paraffin tissue sections from fetuses identified from the pathology database were stained for B cell, T cell, macrophage, and general hematopoietic cell surface markers. Of the 14 fetuses included in the study, 5 had EFE + DCM, 4 had EFE + structural heart disease, and 5 were normal control fetuses. The EFE + DCM group had fewer B cells than the control group (0.15 vs. 0.44 cells/mm(2); p = 0.005). The EFE + heart disease group had both fewer B cells (0.18 vs. 0.44 cells/mm(2); p = 0.08) and T cells (0.29 vs. 0.80 cells/mm(2); p = 0.04) than the control group. The CD4/CD8 ratio was similar in the EFE + DCM and EFE + heart disease groups (1.0 vs. 0.9; p = 0.17) but higher in the EFE + DCM group than in the control group (0.9 vs. 0.3; p = 0.03). The myocardium of fetuses with EFE contains fewer B and T lymphocytes than normal control fetuses.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Performance of modified WHO presumptive criteria for diagnosis of HIV infection in children <18 months admitted to University Teaching Hospital in Lusaka

BACKGROUND: Making a diagnosis of HIV infection in children aged less than 18 months remains a challenge in low resource settings like Zambia due to the limited availability of gold standard testing with HIV DNA PCR. Clinicians in rural areas have to depend on clinical diagnosis to start HAART as they wait for the dry blood spot (DBS) for DNA PCR results sent from the urban centers. METHODS: This descriptive cross-sectional study was performed at the University Teaching Hospital, Lusaka, Zambia. 299 HIV-exposed children aged less than 18 months were enrolled following a consent procedure. Patients were evaluated for HIV infection based on the World Health Organization's presumptive diagnostic criteria (WHO-PDC), integrated management of childhood illnesses (IMCI) criteria, select physical exam abnormalities, and CD4% and findings were compared with HIV-DNA PCR results. RESULTS: Of the 299 exposed patients analyzed, 111(37%) were found to be HIV-positive by DNA PCR. The median CD4% in the infected children was 18%. WHO-PDC used on its own had 23% sensitivity (95% CI 17-32%) and 93% specificity (88-96%), respectively, whereas IMCI criterion had 10% sensitivity (6-17%) and 97% specificity (94-99%), respectively. Multivariate analysis was used to identify the most sensitive predictors when combined with the WHO-PDC and IMCI criterion. WHO-PDC with CD4% improved the sensitivity to 77% (68-83%) with a specificity of 83% (77-88%), positive predictive value (PPV) of 73% (64-80%) and negative predictive value (NPV) of 86% (80-90%). IMCI with CD4% improved sensitivity to 80% (71-87%) with a specificity of 88% (82-92%), PPV 78% (69-85%) and NPV 89% (84-93%). The addition of individual physical exam findings without CD4% improved the sensitivity of WHO-PDC only modestly. When the WHO-PDC, weight<3(rd) percentile, hepatomegaly, splenomegaly, lymphadenopathy and CD4% were combined, the sensitivity improved to 85% (77-90%), specificity 63% (56-70%), PPV 58% (50-65%) and NPV of 88% (81-92%). CONCLUSION: The WHO-PDC clinical algorithm can be improved when combined with a CD4% <25% in children less than 12 months of age and CD4% <20% in those between 12 and 18 months.

Research needs and challenges in the development of HIV diagnostic and treatment monitoring tests for use in resource-limited settings

PURPOSE OF REVIEW

The aim of this article is to review research priorities for current and new technologies to diagnose HIV and to monitor treatment response, including technologies to enumerate CD4 cell counts and quantify plasma viral load, in resource-limited settings.

RECENT FINDINGS

Numerous challenges remain before HIV diagnostic and treatment monitoring technologies can be broadly implemented, especially in rural areas. New technologies that are less costly and complex to use are in development and may be better suited than current technologies for use in resource-limited settings. Investment into research activities is needed for development, evaluation and validation of new technologies. The lack of clarity in the process for evaluation and validation for these technologies affects country and program-level decisions on the appropriateness of technologies for individual settings. Implementation research is needed to assess how best to use CD4 and viral load to guide initiation and management of antiretroviral treatment, as well as how best to scale up diagnosis of HIV serostatus in infants. Studies also need to be conducted to determine if the same CD4 cutoffs can be used in resource-limited settings for initiating antiretroviral therapy and prophylaxis against opportunistic infections due to potential regional differences and the impact of other common co-morbidities on CD4 cell counts.

SUMMARY

Increased availability of antiretroviral therapy in resource-limited settings increases the need for reliable, less costly and simpler to use HIV diagnostic and treatment monitoring technologies. Global leadership is needed to coordinate the research and development necessary to ensure that HIV diagnostic and treatment monitoring technologies are properly evaluated in the setting where they will be used.

HIV-1 infection in infants severely impairs the immune response induced by Bacille Calmette-Guérin vaccine

BACKGROUND

Worldwide, most infants born to mothers infected with human immunodeficiency virus (HIV) receive bacille Calmette-Guérin (BCG) vaccine. Tuberculosis is a major cause of death among infants infected with HIV in sub-Saharan Africa, and it should be prevented. However, BCG may itself cause disease (known as "BCGosis") in these infants. Information regarding the immunogenicity of BCG is imperative for the risk/benefit assessment of BCG vaccination in HIV-infected infants; however, no such data exist.

METHODS

We compared BCG-induced CD4 and CD8 T cell responses, as assessed by flow cytometry, in HIV-infected (n=20), HIV-exposed but uninfected (n=25), and HIV-unexposed (n=23) infants, during their first year of life.

RESULTS

BCG vaccination of the 2 HIV-uninfected groups induced a robust response, which was characterized by CD4 T cells expressing interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and/or interleukin (IL)-2. In contrast, HIV-infected infants demonstrated a markedly lower response throughout the first year of life. These infants also had significantly reduced numbers of polyfunctional CD4 T cells coexpressing IFN-gamma, TNF-alpha, and IL-2, a finding that is thought to indicate T cell quality.

CONCLUSIONS

Infection with HIV severely impairs the BCG-specific T cell response during the first year of life. BCG may therefore provide little, if any, vaccine-induced benefit in HIV-infected infants. Considering the significant risk of BCGosis, these data strongly support not giving BCG to HIV-infected infants.

CD4+/CD8+ T cell ratio for diagnosis of HIV-1 infection in infants: Women and Infants Transmission Study

OBJECTIVE

In this study, we tested the hypothesis that the CD4(+)/CD8(+) T cell ratio could predict HIV infection status in HIV-exposed infants.

METHODS

CD4(+)/CD8(+) T cell ratios were determined from data for live-born singleton infants who had been prospectively enrolled in the Women and Infants Transmission Study. Data for 2208 infants with known HIV infection status (179 HIV-infected and 2029 uninfected infants) were analyzed.

RESULTS

Receiver operating characteristic curves indicated that the CD4(+)/CD8(+) T cell ratio performed better than the proportion of CD4(+) T cells for diagnosis of HIV infection as early as 2 months of age, and this relationship was unaffected by adjustment for maternal race/ethnicity, infant birth weight, gestational age, and gender. At 4 months of age, 90% specificity for HIV diagnosis was associated with 60% sensitivity. For ease of use, graphical estimates based on cubic splines for the time-dependent parameters in a Box-Cox transformation (L), the median (M), and the coefficient of variation (S) were used to create LMS centile curves to show the sensitivity and specificity of CD4(+)/CD8(+) T cell ratios in HIV-infected and uninfected infants until 12 months of age. At 6 months of age, a simplified equation that incorporated sequential CD4(+)/CD8(+) T cell ratios and hematocrit values resulted in improved receiver operating characteristic curves, with 94% positive predictive value and 98% negative predictive value. The positive and negative predictive values remained above 90% in simulated infant populations over a wide range of HIV infection prevalence values.

CONCLUSIONS

In the absence of virological diagnosis, a presumptive diagnosis of HIV infection status can be made on the basis of CD4(+)/CD8(+) T cell ratios in HIV-1-exposed infants after 2 months of age; sensitivity and specificity can be improved at 6 months by using a discriminant analysis equation.

CD4/CD8 T-cell ratio predicts HIV infection in infants: the National Heart, Lung, and Blood Institute P2C2 Study

BACKGROUND

In resource-poor regions of the world, HIV virologic testing is not available.

OBJECTIVE

We sought to evaluate the diagnostic usefulness of the CD4/CD8 T-cell ratio in predicting HIV infection in infants.

METHODS

Data from the 3- and 9-month visits for non-breast-fed infants born to HIV-infected mothers enrolled (1990-1994) in the Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection Study (mother-to-child transmission of HIV, 17%) were analyzed. Data from the 3-month visit for infants enrolled (1985-1996) in the Perinatal AIDS Collaborative Transmission Study (mother-to-child transmission of HIV, 18%) were used for validation.

RESULTS

At 3 months of age, data were available on 79 HIV-infected and 409 uninfected non-breast-fed infants in the Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection Study. The area under the curve (AUC) of the receiver operating characteristic curve at 3 months was higher for the CD4/CD8 ratio compared with the CD4(+) T-cell count (AUC, 0.83 and 0.75; P = .03). The mean CD4/CD8 ratio at the 3-month visit was 1.7 for HIV-infected infants and 3.0 for uninfected infants. A CD4/CD8 ratio of 2.4 at 3 months of age was almost 2.5 times more likely to occur in an HIV-infected infant compared with an uninfected infant (test sensitivity, 81%; posttest probability of HIV, 33%). Model performance in the Centers for Disease Control and Prevention Perinatal AIDS Collaborative Transmission Study validation test (224 HIV-infected and 1015 uninfected 3-month-old infants) was equally good (AUC, 0.78 for CD4/CD8 ratio).

CONCLUSION

The CD4/CD8 T-cell ratio is a more sensitive predictor of HIV infection in infants than the CD4(+) T-cell count.

CLINICAL IMPLICATIONS

The CD4/CD8 T-cell ratio can be used with caution to predict HIV infection in children.