CD45-assisted PanLeucogating for accurate, cost-effective dual-platform CD4+ T-cell enumeration

Safety, Reactogenicity, and Immunogenicity of Human Rotavirus Vaccine RIX4414 in Human Immunodeficiency Virus-positive Infants in South Africa

BACKGROUND

rotavirus and human immunodeficiency virus (HIV) infections are a cause of great public health concern in developing countries. The current study evaluated the safety, reactogenicity, and immunogenicity of RIX4414 vaccine in asymptomatic or mildly symptomatic (clinical stages I and II according to WHO classification) HIV-infected South African infants.

METHODS

a total of 100 HIV-positive infants aged 6 to 10 weeks enrolled in this double-blind, 1:1 randomized, placebo-controlled study were allocated into 2 groups to receive 3 doses of RIX4414 vaccine/placebo according to a 0-, 1-, and 2-month schedule. Routine vaccines were concomitantly administered. Solicited and unsolicited symptoms were recorded for 15 and 31 days after each dose, respectively. Serious adverse events were recorded throughout the study period. Serum antirotavirus IgA concentrations (enzyme-linked immunosorbent assay, cut-off ≥ 20 U/mL) and the immunodeficiency status were determined at screening and 2 months post-Dose 3. Stool samples were analyzed for rotavirus using enzyme-linked immunosorbent assay at predetermined points and during diarrhea episodes.

RESULTS

all symptoms (solicited and unsolicited) occurred at a similar frequency in both groups. Six fatal serious adverse events in RIX4414 and 9 in placebo groups were reported. At 2 months post-Dose 3, the seroconversion rates were 57.1% (95% CI: 34-78.2) in RIX4414 and 18.2% (95% CI: 5.2-40.3) in the placebo group. The mean absolute CD4 cell count, CD4 percentage, and HIV-1 viral load were comparable in both groups at screening and 2 months post-Dose 3. Rotavirus shedding peaked at Day 7 after Dose 1 of RIX4414 with prolonged shedding was observed in 1 infant only.

CONCLUSIONS

: Three doses of RIX4414 vaccine was tolerated well by the South African HIV-positive infants. A satisfactory immune response was mounted without aggravating their immunologic or HIV condition.

Simultaneous counting of two subsets of leukocytes using fluorescent silica nanoparticles in a sheathless microchip flow cytometer

A portable flow cytometer has been recognized as an important tool for many clinical applications such as HIV/AIDS screening in developing countries and regions with limited medical facilities and resources. Conventional flow cytometers typically require multiple detectors for simultaneous identification of multiple subsets of immune cell. To minimize the number of detectors toward portable flow cytometry or to analyze multi-parametric cellular information with minimum number of detectors in conventional flow cytometers, we propose a versatile multiplexed cell-counting method using functional silica nanoparticles (SiNPs). FITC-doped SiNPs, which are 100 times brighter than the FITC molecules itself, were used as new intensity-based fluorescent dye complexes to simultaneously measure two subsets of leukocytes using a single detector. CD45(+)CD4(+) cells tagged with these FITC-doped SiNPs were 50 times brighter than CD45(+)CD4(-) cells tagged only with FITC. To make the overall system compact, a disposable microchip flow cytometer that does not require sheath flow was developed. Combining these dye-doped SiNPs based detection schemes and the sheathless microchip flow cytometer scheme, we successfully identified and counted two subsets of leukocytes simultaneously (R(2) = 0.876). These approaches can be the building blocks for a truly portable and disposable flow cytometer for various clinical cytometry applications.

The diagnostic utility of bone marrow biopsies performed for the investigation of fever and/or cytopenias in HIV-infected adults at Groote Schuur Hospital, Western Cape, South Africa

INTRODUCTION

A bone marrow biopsy is frequently requested in the work-up of patients with human immunodeficiency virus (HIV) infection who present with fever and/or cytopenias in the search for opportunistic infections and malignancies.

METHODS

This is a retrospective review of the results of consecutive bone marrow biopsies performed at our institution over a three-year period on HIV-positive patients for the investigation of fever and/or cytopenias. Clinical data, haematological parameters, morphological features, Ziehl-Neelsen staining and microbiological culture results were analysed. The aim of the study was to determine the diagnostic yield of this investigation.

RESULTS

Sixty-three males and 84 female patients were included for analysis. The bone marrow biopsy gave a high diagnostic yield of 47% (70 patients) and a unique diagnosis in 33% (49 patients). Immune thrombocytopenic purpura and disseminated mycobacterial infections were the most common unique diagnoses made (14%, respectively), followed by malignancies (4%). In this cohort, four cases of primary bone marrow involvement by Hodgkin lymphoma and one case of involvement by non-Hodgkin lymphoma were diagnosed.

CONCLUSION

In our study group, a bone marrow biopsy was a useful investigation with a high diagnostic yield.

Increased vulnerability of rural children on antiretroviral therapy attending public health facilities in South Africa: a retrospective cohort study

BACKGROUND

A large proportion of the 340,000 HIV-positive children in South Africa live in rural areas, yet there is little sub-Saharan data comparing rural paediatric antiretroviral therapy (ART) programme outcomes with urban facilities. We compared clinical, immunological and virological outcomes between children at seven rural and 37 urban facilities across four provinces in South Africa.

METHODS

We conducted a retrospective cohort study of routine data of children enrolled on ART between November 2003 and March 2008 in three settings, namely: urban residence and facility attendance (urban group); rural residence and facility attendance (rural group); and rural residents attending urban facilities (rural/urban group). Outcome measures were: death, loss to follow up (LTFU), virological suppression, and changes in CD4 percentage and weight-for-age-z (WAZ) scores. Kaplan-Meier estimates, logrank tests, multivariable Cox regression and generalized estimating equation models were used to compare outcomes between groups.

RESULTS

In total, 2332 ART-naïve children were included, (1727, 228 and 377 children in the urban, rural and rural/urban groups, respectively). At presentation, rural group children were older (6.7 vs. 5.6 and 5.8 years), had lower CD4 cell percentages (10.0% vs. 12.8% and 12.7%), lower WAZ scores (-2.06 vs. -1.46 and -1.41) and higher proportions with severe underweight (26% vs.15% and 15%) compared with the urban and rural/urban groups, respectively. Mortality was significantly higher in the rural group and LTFU significantly increased in the rural/urban group. After 24 months of ART, mortality probabilities were 3.4% (CI: 2.4-4.8%), 7.7% (CI: 4.5-13.0%) and 3.1% (CI: 1.7-5.6%) p = 0.0137; LTFU probabilities were 11.5% (CI: 9.3-14.0%), 8.8% (CI: 4.5-16.9%) and 16.6% (CI: 12.4-22.6%), p = 0.0028 in the urban, rural and rural/urban groups, respectively. The rural group had an increased adjusted mortality probability, adjusted hazards ratio 2.41 (CI: 1.25-4.67) and the rural/urban group had an increased adjusted LTFU probability, aHR 2.85 (CI: 1.41-5.79). The rural/urban group had a decreased adjusted probability of virological suppression compared with the urban group at any timepoint on treatment, adjusted odds ratio 0.67 (CI: 0.48-0.93).

CONCLUSIONS

Rural HIV-positive children are a vulnerable group, exhibiting delayed access to ART and an increased risk of poor outcomes while on ART. Expansion of rural paediatric ART programmes, with future research exploring improvements to rural health system effectiveness, is required.

A model for continuous quality control incorporating sample-to-sample assessment of optical alignment, fluorescence sensitivity, and volumetric operation of flow cytometers

BACKGROUND

Bead count rate (BCR) monitoring successfully identifies pipetting error during single platform CD4 enumeration. Despite rigorous prescribed quality control performed, preliminary data suggested that BCR outliers could also be attributed to occasional failure of flow cytometric volumetric operation. The aim of this report was to use counting beads in a model of continuous quality control (CQC) to monitor overall flow cytometric performance (laser alignment, fluorescence stability and volumetric operation).

METHODS

The proposed CQC model used FlowCheck and IMMUNOTROL blood controls daily. Extended monitoring of fluidics (FPV; beads and sheath only) and sample preparation (SPV; blood, IMMUNOPREP and beads) was done daily on five flow cytometers over five consecutive days prior to testing patient samples. Sample-to-sample CQC included monitoring BCR, selected time/fluorescence histograms (Time vs. Count; Time vs. Fluorescence and Forward Scatter vs. Fluorescence) and full peak coefficient of variation (FPCV) for 2000 samples tested.

RESULTS

Prescribed quality controls showed Half Peak CV values of <2% (FlowCheck) with Immunotrol within 0.5SD of the target means. Laser stability was confirmed (FPCV values <2%). However, fluidics (volumetric operation) fluctuated as indicated by a 3.2% BCR outlier rate of 2,000 samples tested (minus pipetting error) despite optimal fluidics performance verified at start-up (FPV CV < 3%).

CONCLUSIONS

Sustained laser stability was confirmed with Time vs. Fluorescence histograms, but Time vs. Count histograms were insufficient to detect intermittent volumetric failure. The proposed CQC model, incorporating BCR monitoring with time/fluorescence histograms and FPCV monitoring can identify all volumetric inconsistencies in real-time.

FOXP3 expression is upregulated in CD4T cells in progressive HIV-1 infection and is a marker of disease severity

Background

Understanding the role of different classes of T cells during HIV infection is critical to determining which responses correlate with protective immunity. To date, it is unclear whether alterations in regulatory T cell (Treg) function are contributory to progression of HIV infection.

Methodology

FOXP3 expression was measured by both qRT-PCR and by flow cytometry in HIV-infected individuals and uninfected controls together with expression of CD25, GITR and CTLA-4. Cultured peripheral blood mononuclear cells were stimulated with anti-CD3 and cell proliferation was assessed by CFSE dilution.

Principal Findings

HIV infected individuals had significantly higher frequencies of CD4⁺FOXP3⁺ T cells (median of 8.11%; range 1.33%–26.27%) than healthy controls (median 3.72%; range 1.3–7.5%; P = 0.002), despite having lower absolute counts of CD4⁺FOXP3⁺ T cells. There was a significant positive correlation between the frequency of CD4⁺FOXP3⁺ T cells and viral load (rho = 0.593 P = 0.003) and a significant negative correlation with CD4 count (rho = −0.423 P = 0.044). 48% of our patients had CD4 counts below 200 cells/µl and these patients showed a marked elevation of FOXP3 percentage (median 10% range 4.07%–26.27%). Assessing the mechanism of increased FOXP3 frequency, we found that the high FOXP3 levels noted in HIV infected individuals dropped rapidly in unstimulated culture conditions but could be restimulated by T cell receptor stimulation. This suggests that the high FOXP3 expression in HIV infected patients is likely due to FOXP3 upregulation by individual CD4⁺ T cells following antigenic or other stimulation.

Conclusions/Significance

FOXP3 expression in the CD4⁺ T cell population is a marker of severity of HIV infection and a potential prognostic marker of disease progression.

Increased incidence of meningococcal disease in HIV-infected individuals associated with higher case-fatality ratios in South Africa

OBJECTIVES

We aimed to compare the incidence of meningococcal disease amongst HIV-infected and uninfected individuals and to evaluate whether HIV is a risk factor for mortality and bacteremia amongst patients with meningococcal disease.

DESIGN

Cohort surveillance study.

METHODS

We conducted laboratory-based surveillance for meningococcal disease in Gauteng Province, South Africa. HIV status and outcome data were obtained at sentinel sites. Incidence in HIV-infected and uninfected persons was calculated assuming a similar age-specific HIV prevalence in tested and untested individuals. Risk factors for death and bacteremia (as compared with meningitis) were evaluated using multivariable logistic regression.

RESULTS

From 2003 to 2007, 1336 meningococcal cases were reported. Of 504 patients at sentinel sites with known outcome, 308 (61%) had HIV serostatus data. HIV prevalence amongst cases of meningococcal disease was higher than the population HIV prevalence in all age groups. The incidence of meningococcal disease in HIV-infected individuals was elevated in all age groups with an age-adjusted relative risk of 11.3 [95% confidence interval (CI) 8.9-14.3, P < 0.001]. The case-fatality ratio (CFR) was 20% (27/138) amongst HIV-infected and 11% (18/170) amongst HIV-uninfected individuals [odds ratio (OR) 2.1, 95% CI 1.1-3.9]. On multivariable analysis, CFR was greater amongst patients with bacteremia (35%, 29/82) compared with meningitis (7%, 16/226) (OR 7.8, 95% CI 3.4-17.7). HIV infection was associated with increased odds of bacteremia (OR 2.7, 95% CI 1.5-5.0).

CONCLUSION

HIV-infected individuals may be at increased risk of meningococcal disease. The increased CFR in HIV-infected patients may be explained by their increased odds of bacteremia compared to meningitis.

Clinical evaluation of a simple image cytometer for CD4 enumeration on HIV-infected patients

BACKGROUND

Affordable, easy-to-use, and reliable CD4(+) T lymphocyte enumeration systems are needed in resource-constrained settings to monitor HIV.

METHODS

A simple image cytometer was used to count fluorescently labeled CD4(+) T and CD8(+) T lymphocytes from CD3 immunomagnetically selected cells on blood specimens of 460 HIV-1-infected patients in Siriraj Hospital, Bangkok, Thailand. Results were compared with flow cytometry (FCM).

RESULTS

CD4(+) T lymphocyte counts by image cytometer were comparable (R > or = 0.97) with those by the FACSCount and the FACScan with a bias of 7.3 and 9.1%, respectively. At very low CD4(+) T lymphocyte counts (< or =50/microl) some over-count outliers were observed by the FACScan and image cytometer when compared with the FACSCount. For CD8 enumeration, the image cytometer showed a good correlation (R = 0.96) and a consistent undercount (approximately 17%) when compared with the FACSCount.

CONCLUSIONS

Evaluation of the image cytometer for CD4 and CD8 enumeration demonstrated comparable results with FCM on a population of HIV-1-infected patients. The image cytometer is a good alternative method for point-of-care settings in resource-constrained countries.

Basophil sensitivity through CD63 or CD203c is a functional measure for specific immunotherapy

Background

Subcutaneous Immunotherapy (SCIT) modifies the allergic response and relieves allergic symptoms. SCIT is the only and a very effective treatment for insect venom allergy. We hypothesized that basophil sensitivity, measured through the basophil activation test, would decrease during SCIT up dosing. Expression of CD203c was compared to CD63 as marker for basophil activation, using a Bland Altman plot and ROC curves.

Methods

Patients (n = 18) starting subcutaneous SCIT for wasp allergy with an up dosing scheme of 7 to 11 weeks were enrolled. Heparinised blood samples were drawn at weeks 1-4, 7 and at the first maintenance visit. Basophils were stimulated at 7 log dilutions of V. vespula allergen for 15 min, and were stained with CD203c and CD63. Basophils were identified as CD203c⁺ leukocytes, and the proportion of CD63⁺ and CD203c⁺ cells were plotted against allergen concentration. A sigmoid curve was fitted to the points, and the allergen concentration at which half of the maximal activation was achieved, LC50, was calculated. In another series of experiments, LC50 calculated in whole blood (AP) was subtracted from LC50 calculated with basophils suspended in plasma from a nonatopic donor (HS) to determine the protective effect of soluble factors in blood of patients treated with SCIT.

Results

Heparin blood basophil activation was similar through CD63 and CD203c. Basophils were significantly more sensitized three weeks after initiation of SCIT compared to baseline (p < 0,01). The difference in LC50 increased by 1,04 LC50 units (p = 0,04) in patients that had just achieved maintenance dose compared with patients before initiating SCIT. When maintenance allergen concentrations had been reached, an increase in the protective plasma component was documented. Blood basophil concentration was marginally reduced by SCIT.

Conclusion

Basophil activation is a versatile and sensitive tool that measures changes in the humoral immune response to allergen during SCIT.

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.

Lymphocyte subsets in healthy Malawians: implications for immunologic assessment of HIV infection in Africa

Background

CD4⁺T lymphocyte measurements are the most important indicator of mortality in HIV-infected individuals in resource-limited settings. There is currently a lack of comprehensive immunophenotyping data from African populations to guide the immunologic assessment of HIV infection.

Objective

To quantify variation in absolute and relative lymphocyte subsets with age in healthy Malawians.

Methods

Lymphocyte subsets in peripheral blood of 539 healthy HIV-uninfected Malawians stratified by age were enumerated by flow cytometry.

Results

B and T–lymphocyte and T-lymphocyte subset absolute concentrations peaked in early childhood then decreased to adult levels, whereas lymphocyte subset proportions demonstrated much less variation with age. Adult lymphocyte subsets were similar to those in developed countries. In contrast, high B-lymphocyte and CD8⁺T-lymphocyte levels among children under 2 years, relative to those in developed countries, resulted in low CD4⁺T-lymphocyte percentages that varied little between 0 and 5 years (35% to 39%). The CD4⁺T-lymphocyte percentages in 35% of healthy children under 1 year and 18% of children age 1 to 3 years were below the World Health Organization threshold defining immunodeficiency in HIV-infected children in resource-limited settings. Thirteen percent of healthy children under 18 months old had a CD4:CD8T-lymphocyte ratio <1.0, which is commonly associated with HIV infection. All immunologic parameters except absolute natural killer lymphocyte concentration varied significantly with age, and percentage and overall absolute CD4⁺T-lymphocyte counts were higher in females than males.

Conclusion

Although lymphocyte subsets in Malawian adults are similar to those from developed countries, CD4⁺T-lymphocyte percentages in young children are comparatively low. These findings need to be considered when assessing the severity of HIV-related immunodeficiency in African children under 3 years.

Polychromatic immunophenotypic characterization of T cell profiles among HIV-infected patients experiencing immune reconstitution inflammatory syndrome (IRIS)

Objective

To immunophenotype CD4⁺ and CD8⁺ T cell sub-populations in HIV-associated immune reconstitution inflammatory syndrome (IRIS).

Design

Nested case-control immunological study.

Methods

ART-naïve HIV-infected patients were prospectively observed for IRIS during the first 6 months of ART. Twenty-two IRIS cases and 22 ART-duration matched controls were sampled for T cell immunophenotyping.

Results

IRIS cases demonstrated significantly lower CD4 cell counts compared to controls (baseline: 79 versus 142, p = 0.02; enrollment: 183 versus 263, p = 0.05, respectively) with no differences in HIV RNA levels. Within CD4⁺T cells, cases exhibited more of an effector memory phenotype compared to controls (40.8 versus 27.0%, p = 0.20), while controls trended towards a central memory phenotype (43.8 versus 30.8%, p = 0.07). Within CD8⁺ T cells, controls exhibited more central memory (13.9 versus 7.81%, p = 0.01, respectively) and effector (13.2 versus 8.8%, p = 0.04, respectively) phenotypes compared to cases, whereas cases demonstrated more terminal effectors than controls (28.8 versus 15.1%, p = 0.05). Cases demonstrated increased activation of CD8⁺ T cell effector memory, terminal effector, and effector subsets than controls (p = 0.04, 0.02, and 0.02, respectively).

Conclusion

CD4⁺ and CD8⁺ T cell subset maturational phenotypes were heterogeneous among IRIS cases and controls. However, IRIS cases demonstrated significant increases in activation of CD8⁺ T cell effector subpopulations.

Impact of aciclovir on genital and plasma HIV-1 RNA in HSV-2/HIV-1 co-infected women: a randomized placebo-controlled trial in South Africa

BACKGROUND

Several studies suggest that herpes simplex virus type 2 (HSV-2) may enhance HIV-1 transmission and disease progression.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of aciclovir 400 mg twice daily for 3 months in 300 HSV-2/HIV-1 co-infected women not yet on highly active antiretroviral therapy (HAART). Participants were evaluated prerandomization and at monthly visits for 3 months. Primary outcomes were the detection and quantity of genital HIV-1 RNA at the month 3 (M3) visit. Analyses were also undertaken using data from all visits. The treatment effects on plasma HIV-1 RNA, CD4 cell count and genital HSV-2 DNA were also assessed.

RESULTS

At M3 fewer women had detectable genital HIV in the aciclovir group compared to placebo, but this was not significant [61/132 (46%) vs. 71/137 (52%), risk ratio (RR) 0.89, 95% confidence interval (CI) 0.70-1.14; P = 0.36]. There was also little difference in quantity of HIV-1 RNA among shedders (+0.13 log10 copies/ml, 95% CI -0.14 to 0.39) at M3. However, aciclovir significantly decreased the frequency of HIV-1 shedding over all visits [adjusted odds ratio (OR) 0.57, 95% CI 0.36-0.89]. Significant reductions in M3 plasma HIV-1 RNA (-0.34 log10 copies/ml, 95% CI 0.15-0.54), genital HSV-2 DNA (8 vs. 20%, RR 0.37, 95% CI 0.19-0.73) and genital ulceration (8 vs. 18%, RR 0.43, 95% CI 0.22-0.84) were observed in the aciclovir group.

CONCLUSION

HSV-2 suppressive therapy, by reducing HIV-1 plasma viral load and altering the pattern of genital HIV-1 shedding, may contribute to the reduction in sexual transmission of HIV-1 and may delay the requirement for HAART initiation.

Bone marrow aspirate and biopsy: a pathologist's perspective. II. interpretation of the bone marrow aspirate and biopsy

Bone marrow examination has become increasingly important for the diagnosis and treatment of hematologic and other illnesses. Morphologic evaluation of the bone marrow aspirate and biopsy has recently been supplemented by increasingly sophisticated ancillary assays, including immunocytochemistry, cytogenetic analysis, flow cytometry, and molecular assays. With our rapidly expanding knowledge of the clinical and biologic diversity of leukemia and other hematologic neoplasms, and an increasing variety of therapeutic options, the bone marrow examination has became more critical for therapeutic monitoring and planning optimal therapy. Sensitive molecular techniques, in vitro drug sensitivity testing, and a number of other special assays are available to provide valuable data to assist these endeavors. Fortunately, improvements in bone marrow aspirate and needle technology has made the procurement of adequate specimens more reliable and efficient, while the use of conscious sedation has improved patient comfort. The procurement of bone marrow specimens was reviewed in the first part of this series. This paper specifically addresses the diagnostic interpretation of bone marrow specimens and the use of ancillary techniques.

Antiretroviral therapy and early mortality in South Africa

OBJECTIVE

To describe province-wide outcomes and temporal trends of the Western Cape Province antiretroviral treatment (ART) programme 5 years since inception, and to demonstrate the utility of the WHO monitoring system for ART.

METHODS

The treatment programme started in 2001 through innovator sites. Rapid scaling-up of ART provision began early in 2004, located predominantly in primary-care facilities. Data on patients starting ART were prospectively captured into facility-based registers, from which monthly cross-sectional activity and quarterly cohort reports were aggregated. Retention in care, mortality, loss to follow-up and laboratory outcomes were calculated at 6-monthly durations on ART.

FINDINGS

By the end of March 2006, 16 234 patients were in care. The cohort analysis included 12 587 adults and 1709 children. Women accounted for 70% of adults enrolled. After 4 and 3 years on ART respectively, 72.0% of adults (95% confidence interval, CI: 68.0-75.6) and 81.5% (95% CI: 75.7-86.1) of children remained in care. The percentage of adults starting ART with CD4 counts less than 50 cells/microl fell from 51.3% in 2001 to 21.5% in 2005, while mortality at 6 months fell from 12.7% to 6.6%, offset in part by an increase in loss to follow-up (reaching 4.7% at 6 months in 2005). Over 85% of adults tested had viral loads below 400 copies/ml at 6-monthly durations until 4 years on ART.

CONCLUSION

The location of care in primary-care sites in this programme was associated with good retention in care, while the scaling-up of ART provision was associated with reduced early mortality.

CD4 immunophenotyping in HIV infection

The ability to rapidly identify immune cell subsets such as CD4 cells, which became possible around the same time as the onset of the HIV/AIDS pandemic, was one of the greatest advances in clinical and diagnostic immunology. The evolution of this global pandemic and the subsequent development of treatment strategies to prolong the life of infected individuals mean that it is now more crucial than ever that we develop affordable, reliable and accurate methods for the enumeration of CD4 cells. Here, we provide an overview of the historical developments in CD4 enumeration technologies that are related to HIV infection, and summarize the current technological challenges that must be overcome to meet the needs of those living with HIV infection.

Flow rate calibration for absolute cell counting rationale and design

There is a need for absolute leukocyte enumeration in the clinical setting, and accurate, reliable (and affordable) technology to determine absolute leukocyte counts has been developed. Such technology includes single platform and dual platform approaches. Derivations of these counts commonly incorporate the addition of a known number of latex microsphere beads to a blood sample, although it has been suggested that the addition of beads to a sample may only be required to act as an internal quality control procedure for assessing the pipetting error. This unit provides the technical details for undertaking flow rate calibration that obviates the need to add reference beads to each sample. It is envisaged that this report will provide the basis for subsequent clinical evaluations of this novel approach.

Comparison of different methodologies for CD4 estimation in a clinical setting

OBJECTIVE

To compare flow cytometry assays, using traditional dual platform (DP) or newer single platform (SP) for CD4 enumeration.

METHOD

Records of subjects enrolled in four separate clinical trials using the same central laboratory [SP methodology (Trucount)] were reviewed retrospectively. Eighteen subjects had 60 matching contemporaneous samples at multiple timepoints.

RESULTS

DP flow cytometry yielded higher CD4 counts in 50/60 assays (83%). CD4 count and percentage by the two methods showed strong correlation for the counts (r=0.965, P<0.0001) and percentages (r=0.959, P<0.0001). Bland-Altman plot analysis showed that the limits of variation were within agreeable limits of +/-2SD in 56/60 (93.3%) samples tested. Twenty-five (42%) samples had a difference of >50 cells/microL. Of these six (24%) exceeded 100 cells.

CONCLUSION

This study is in agreement with previous reports of strong correlation between DP and SP flow cytometry. This review found differences in CD4 counts in a high proportion of samples tested highlighting the importance for clinicians to be aware of such differences when interpreting results from the two methods.

Bacillus Calmette-Guérin (BCG) vaccine-induced complications in children treated with highly active antiretroviral therapy

OBJECTIVE

To describe the frequency, risk factors, and clinical features of bacillus Calmette-Guérin (BCG) complications in HIV-infected children treated with highly active antiretroviral therapy (HAART).

METHODS

A retrospective study of children started on HAART between August 2002 and November 2004 was completed.

RESULTS

Six percent (21/352; 95% CI 3.7-8.0%) developed BCG complications. All developed ipsilateral axillary lymphadenitis; one child had suspected disseminated BCG infection. There were 14 females; median age at start of HAART was 5 months. BCG disease developed a median of 34 days after starting HAART. At baseline and 6 months into HAART, the median CD4 percentage and log(10) viral load were 12.3/6.1 and 23.9/4.5, respectively. Seventeen (81%) of the patients were treated with either zidovudine or stavudine combined with lamivudine and ritonavir. Young age and high baseline viral load were independent risk factors for development of BCG complications. Mycobacterium bovis BCG was isolated in 70% of patients who underwent incision and drainage of abscesses at the vaccination site or regional lymph nodes.

CONCLUSIONS

This study identified a high prevalence of BCG complications in children on HAART. A clinical case definition of BCG immune reconstitution syndrome independent of laboratory parameters for use in resource-limited settings should be developed.

Determination of blood leukocyte concentration with constant volume acquisition on a flow cytometer is comparable to individualized single platform testing with beads as internal reference standard

Flow cytometers have a constant flow rate. This enables flow cytometers to measure leukocyte concentrations in a determined volume by acquiring data at a fixed rate over a fixed time and is called constant volume acquisition (CVA). The volume aspirated by a FACS Calibur flow cytometer in 4 min at a high rate has a median of 163 microl (IQR 156-170) with TruCount tubes. Leukocyte concentrations of 26 healthy volunteers were measured twice on up to four occasions with a Bürker-Türk chamber, by single platform technology (SPT) with TruCount tubes and on the same data set using CVA. Total leukocyte concentrations determined by CVA correlated better with measurements in a Bürker-Türk (BT) chamber than with SPT. Concentrations determined with CVA were 1.86% higher than with BT whereas SPT data were 5.35% higher than BT (p<0.001), and 3.36% higher than CVA (p<0.001). At leukocyte concentrations <6 million/ml SPT correlated better with BT than CVA. The SPT measurement may be more variable because it depends on measurement of the number of beads aliquoted, the number of beads and leukocytes aspirated, where both BT counting and CVA measurements only depend on the number of leukocytes counted. CVA with PanLeukoGating can be established using microscopy as a reference, and is comparable to BT chamber and SPT determination. Leukocyte concentrations can be measured with CVA on flow cytometers in research and clinical settings.

Affordable pediatric CD4 counting by flow cytometry in Malawi

Background

Rapid expansion of antiretroviral therapy in Malawi has occurred in the relative absence of suitable pediatric CD4 counting facilities. We have recently validated in adults a simplified affordable flow cytometric CD4 counting method, the Blantyre count. There is a need for this technology to transfer to government laboratories run by local staff, and to be validated in children, where %CD4/lymphocyte values are required.

Methods

We assessed agreement of %CD4/lymphocyte values determined by the Blantyre count and Panleucogate methods on an EPICS XL-MCL flow cytometer on 113 venous blood samples from HIV-seropositive children in Blantyre, Malawi. All assays were performed by two Malawian laboratory technicians.

Results

Overall bias between the two methods was −0.13% (95% CI −0.37 to 0.11) and limits of agreement were −2.69 to 2.43% (95% CI −3.11 to −2.27 and 2.01 to 2.85). Limits of agreement were within −3.00 and 3.00 for each laboratory technician. Coefficient of variation for the Blantyre count assay was 2.0% and samples showed good stability over 5 days.

Conclusions

The Blantyre count method can accurately determine %CD4/lymphocyte values in blood of HIV-seropositive children on an EPIC XL-MCL flow cytometer at a reagent cost of US $0.21 per test or less. The assay can be competently carried out by local laboratory technicians.

African regional external quality assessment for CD4 T-cell enumeration: development, outcomes, and performance of laboratories

BACKGROUND

An independent African Regional External Quality Assessment Scheme (AFREQAS) was implemented from Johannesburg. The aim was to establish a network of CD4 laboratories supporting HIV/AIDS anti-retroviral therapy programs and improve the quality of regional CD4 testing with EQA assessment, feedback, remedial action, and technical training. The overall performance from 2002 to 2006 (Trials 1-20) is reported, together with cumulative longitudinal performance of the different CD4 methods used.

METHODS

Stabilized blood samples with "normal" and/or "low" CD4 values were shipped over 20 Trials. Data was analyzed for each trial including trimmed mean, standard deviation, and percentage coefficient of variation (%CV); "Residual" and SDI values were also calculated for each participating laboratory for both absolute CD4 counts (CD4abs) and CD4 percentage of lymphocytes values (CD4%/Ly). Standardized individual laboratory SDI values across 20 trials were analyzed according to CD4 method.

RESULTS

Average participation was 91.5%. Overall AFREQAS between-laboratory reproducibility (trimmed %CV) was 10.5% and 9.1% for absolute CD4 and CD4%/Ly, respectively. For the respective CD4abs and CD4%/Ly values in the trials where "normal" material was shipped trimmed %CV of 10.9 and 7.3% were noted, and in "low" value shipments %CV of 13.8% and 12.4% were noted. Cumulative absolute CD4 SDI analysis revealed the best between-laboratory precision amongst FACSCount and PanLeucogating (PLG-CD4) users (both SD of SDI = <1.2 and %CV of <<8%). Dual Platform or Single Platform algorithm-based systems and certain volumetric methods (laboratories who used Partec CyFlow instruments) had higher numbers of outlying laboratories (>12-25%CV and SD(SDI) > 2.2 noted), indicating that additional technical training and/or manufacturer support was required.

CONCLUSIONS

Participation in an AFREQAS with feedback and remedial action improves the quality of CD4 testing. African laboratory professionals can easily master CD4 counting technologies. However, the introduction of the simplest and most cost-effective methodologies is required to take ownership, and enable the delivery of quality CD4 counts in vast numbers necessary to support expansion of African ART programs.

Challenges in implementing CD4 testing in resource-limited settings

The scale-up of HIV antiretroviral therapy in recent years has led to a rapid increase in CD4 and CD4% count capacity to meet the diagnostic needs of staging and monitoring disease progression and treatment efficacy in adults and infants. The speed of implementation of this technology has been unrivalled in recent years and has met challenges with technology selection, laboratory infrastructure development, human resource limitations, cost-effectiveness, instrument maintenance, and ensuring testing access and quality. The lessons learned from dealing with these challenges have helped strengthen existing laboratory systems for other diagnostics. They may also facilitate the implementation of new diagnostics in future.

A North American multilaboratory study of CD4 counts using flow cytometric panLeukogating (PLG): a NIAID-DAIDS Immunology Quality Assessment Program Study

BACKGROUND

The global HIV/AIDS pandemic and guidelines for initiating anti-retroviral therapy (ART) and opportunistic infection prophylaxis demand affordable, reliable, and accurate CD4 testing. A simple innovative approach applicable to existing technology that has been successfully applied in resource-challenged settings, PanLeukogated CD4 (PLG), could offer solutions for cost saving and improved precision.

METHODS

Day-old whole blood from 99 HIV+ donors was simultaneously studied in five North-American laboratories to compare the performance of their predicate methods with the dual-platform PLG method. The predicate technology included varying 4-color CD45/CD3/CD4/CD8 protocols on different flow cytometers. Each laboratory also assayed eight replicate specimens of day-old blood from 10 to 14 local donors. Bias and precision of predicate and PLG methods was studied between- and within-participating laboratories.

RESULTS

Significantly (P < 0.0001) improved between-laboratory precision/coefficient of variation (CV%) was noted using the PLG method (overall median 9.3% vs. predicate median CV 13.1%). Within-laboratory precision was also significantly (P < 0.0001) better overall using PLG (median 4.6% vs. predicate median CV 6.2%) and in 3 of the 5 laboratories. PLG counts tended to be 11% smaller than predicate methods (P < 0.0001) for shipped (median of predicate-PLG = 31) and local specimens (median of predicate-PLG = 23), both overall and in 4 of 5 laboratories (median decreases of 4, 16, 20, and 21% in shipped specimens); the other laboratory had a median increase of 5%.

CONCLUSION

Laboratories using predicate CD4 methods similar to those in this study could improve their between-laboratory and their within-laboratory precision, and reduce costs, by switching to the PLG method after adequate training, if a change (usually, a decrease) in CD4 counts is acceptable to their health systems.

The changing pattern of "smart" flow cytometry (S-FC) to assist the cost-effective diagnosis of HIV, tuberculosis, and leukemias in resource-restricted conditions

There is a need to introduce cytometry into areas of the globe that have remained virtually untouched by modern laboratory medicine. With the demand to carry out tests on 100,000 s of individuals requiring antiretroviral therapy (ART), flow cytometry must remain simple and cost-effective - while being sustainable and industry supported as well as proven by quality assessment (QA). This outlook is referred to as "smart flow cytometry" (S-FC). There are five main areas where the power of S-FC is demonstrated. These are: (i) the use of CD45 to assist precise cell counting in blood and tissue samples; (ii) the primary CD4 gating to count CD4+ T cells in patients waiting for ART, including the combination (i) and (ii) in the panleucogating (PLG) protocol; (iii) monitoring of human immunodeficiency virus (HIV+) patients during ART by the decreasing levels of lymphocyte activation in a CD8/CD38 test - leading to economies of viral-load assays; (iv) in tuberculosis and HIV-TB coinfections the use of TB-antigen-stimulated cytokine-synthetic CD4+ T cells to identify active disease; and (v) the utilization of "minimal residual disease (MRD)-Lite" technology in patients 19 days after the start of antileukemic therapy to detect MRD. These methods of S-FC have been successfully introduced in "resource-restricted" countries with international and local QA.

Flow cytometric lymphocyte subset enumeration: 10 years of external quality assessment in the Benelux countries

A biannual external quality assessment (EQA) scheme for flow cytometric lymphocyte immunophenotyping is operational in the Benelux countries since 1996. We studied the effects of the methods used on assay outcome, and whether or not this EQA exercise was effective in reducing between-laboratory variation. Eighty test samples were distributed in 20 biannual send-outs. Per send-out, 50-71 participants were requested to enumerate CD3+, CD4+, and CD8+ T cells, B cells, and NK cells, and to provide methodological details. Participants received written debriefings with personalized recommendations after each send-out. For this report, data were analyzed using robust multivariate regression. Five variables were associated with significant positive or negative bias of absolute lymphocyte subset counts: (i) platform methodology (i.e., single-platform assays yielded lower CD4+ and CD8+ T-cell counts than did dual-platform assays); (ii) sample preparation technique (i.e., assays based on mononuclear cells isolation yielded lower T-cell counts than those based on red cell lysis); (iii) gating strategies based on CD45 and sideward scatter gating of lymphocytes yielded higher CD4+ T-cell counts than those based on "backgating" of lymphocytes guided by CD45 and CD14); (iv) stabilized samples were generally associated with higher lymphocyte subset counts than nonstabilized samples; and (v) laboratory. Platform methodology, sample stabilization, and laboratory also affected assay variability. With time, assay variability tended to decline; this trend was significant for B-cell counts only. In addition, significant bias and variability of results, independent of the variables tested for in this analysis, were also associated with individual laboratories. In spite of our recommendations, participants tended to standardize their techniques mainly with respect to sample preparation and gating strategies, but less with absolute counting techniques. Failure to fully standardize protocols may have led to only modest reductions in variability of results between laboratories.

Diagnostic accuracy and clinical utility of a simplified low cost method of counting CD4 cells with flow cytometry in Malawi: diagnostic accuracy study

OBJECTIVES

To assess the diagnostic accuracy and clinical utility of a simplified low cost method for measuring absolute and percentage CD4 counts with flow cytometry.

DESIGN

A CD4 counting method (Blantyre count) using a CD4 and CD45 antibody combination with reduced blood and reagent volumes. Diagnostic accuracy was assessed by measuring agreement of the index test with two other assays (TruCount and FACSCount). Clinical utility was investigated by comparing CD4 counts with the new assay with WHO clinical staging in patients with HIV.

SETTING

Research laboratories and antiretroviral therapy clinic at a medical school and large government hospital in southern Malawi.

PARTICIPANTS

Assay comparisons were performed on consecutive blood samples sent for CD4 counting from 129 patients with HIV. Comparison of CD4 count with staging was conducted on 253 consecutive new patients attending the antiretroviral therapy clinic.

MAIN OUTCOME MEASURES

Limits of agreement with 95% confidence intervals between index test and reference standards.

RESULTS

The limits of agreement for Blantyre count and TruCount were excellent (cell count -48.9 to 27.0 x10(9)/l for absolute counts in the CD4 range <400x10(9)/l and -2.42% to 2.37% for CD4 percentage). The assay was affordable with reagent costs per test of $0.44 ( pound0.22, euro0.33) for both absolute count and CD4 percentage, and $0.11 for CD4 percentage alone. Of 193 patients with clinical stage I or II disease, who were ineligible for antiretroviral therapy by clinical staging criteria, 73 (38%) had CD4 counts <200x10(9)/l. By contrast, 12 (20%) of 60 patients with stage III or IV disease had CD4 counts >350x10(9)/l.

CONCLUSIONS

This simplified method of counting CD4 cells with flow cytometry has good agreement with established commercial assays, is affordable for routine clinical use in Africa, and could improve clinical decision making in patients with HIV.

Effect of ex vivo storage and Cyto-Chex on the expression of P-selectin glycoprotein ligand-1 (PSGL-1) on human peripheral leukocytes

P-selectin glycoprotein ligand-1 (PSGL-1) is expressed on leukocytes and its expression is elevated in asthma and chronic obstructive pulmonary disease. This study assessed whether the cell stabilisation solution Cyto-Chex is able to preserve such quantitative differences for delayed testing. Peripheral blood was mixed with Cyto-Chex and stored refrigerated or at ambient temperature. Aliquots were tested by flow cytometry 2 to 168 h after collection for PSGL-1, CD3, CD4, CD8, and CD16 expression and marker-positive cell counts. Compared with controls a marked reduction of staining intensities is seen at all time points for all markers, irrespective of the storage temperature. This loss of bright staining did not or only moderately decrease marker-positive cell counts except for PSGL-1+ lymphocytes which declined in parallel with staining intensity. These findings indicate that Cyto-Chex is not able to preserve the expression or affinity to antibodies of surface markers to allow delayed determination of quantitative differences or detection of weakly staining cells. Immunophenotyping is mostly possible for 7 days after collection, however, this has to be tested for each marker and cell type of interest.

Comparison of capillary based microflurometric assay for CD4+ T cell count estimation with dual platform Flow cytometry

The CD4+ T cell count estimation is an important monitoring tool for HIV disease progression and efficacy of anti-retroviral treatment (ART). Due to availability of ART at low cost in developing countries, quest for reliable cost effective alternative methods for CD4+ T cell count estimation has gained importance. A simple capillary-based microflurometric assay (EasyCD4 System, Guava Technology) was compared with the conventional flow cytometric assay for estimation of CD4+ T cell counts in 79 HIV infected individuals. CD4+ T cell count estimation by both the assays showed strong correlation (r = 0.938, p < 0.001, 95% CI 0.90 to 0.96). The Bland Altman plot analysis showed that the limits of variation were within agreeable limits of ± 2SD (-161 to 129 cells/mm³). The Easy CD4 assay showed 100% sensitivity for estimating the CD4+ T cell counts < 200 cells/mm³ and < 350 cells/mm³ and 97% sensitivity to estimate CD4+ T cell count < 500 cells/mm³. The specificity ranged from 82 to 100%. The Kappa factor ranged from 0.735 for the CD4+ T cell counts < 350 cells/mm³ to 0.771 for < 500 cells/mm³ CD4+ T cell counts. The system works with a simple protocol, is easy to maintain and has low running cost. The system is compact and generates minimum amount of waste. Hence the EasyCD4 System could be applied for estimation of CD4+ T cell counts in resource poor settings.

Validation of Primary CD4 Gating as an Affordable Strategy for Absolute CD4 Counting in Cambodia

OBJECTIVE

To validate primary CD4 gating in lysed whole blood for absolute CD4 counts in fresh and aged blood using an affordable compact volumetric commercial flow cytometer.

DESIGN

Comparison of CD4 counts between the FACSCount and the 2-parameter CyFlow SL Green.

METHODS

One hundred twenty fresh blood samples from patients likely to be infected with HIV were simultaneously run on a FACSCount at the Pasteur Institute of Cambodia and on a CyFlow SL Green at the Sihanouk Hospital Center of Hope (SHCH), Phnom Penh, Cambodia. Intra- and interrun precision was assessed using 2 blood samples. Stability of CD4 counting in blood stored up to 96 hours at room temperature was assessed using 27 blood samples.

RESULTS

CD4 counts on the CyFlow SL Green and on the FACSCount correlated well apart from a relative bias (R = 0.993, bias of -9.5%, 95% confidence interval [CI]: -11.8% to -7.1%, limits of agreement: -32.5% to 13.6%). Intra- and interrun variability ranged from 3% to 5% and from 5% to 6%, respectively. CD4 counts on aged blood using the CyFlow SL Green showed an interassay variability of <10%.

CONCLUSIONS

Primary CD4 gating in lysed whole blood using the CyFlow SL Green is an affordable and precise method for CD4 counting. Because the fluorescence (FL) and light scatter signals have to be analyzed manually, however, intensive training of the technician and/or operator is imperative.

Increased CD154 Expression in Uninfected Infants Born to HIV-Positive Mothers Exposed to Antiretroviral Prophylaxis

Although prevention of mother-to-child HIV transmission by antiretroviral drugs has been shown to be effective, the short- and long-term effects of treatment are not well known. Several reports suggest that antiretroviral drugs act not only by inhibiting viral replication, but also by improving antiviral immunity. In particular, treatment with nucleoside analogs was found to increase CD40 ligand (CD40L; CD154) levels, an inducible molecule expressed on activated T lymphocytes. The present study investigated potential immunostimulatory effects of antiretroviral treatment (ART) in uninfected HIV-exposed infants, receiving either ante- or postnatal therapy to reduce the transmission rate. To this end, we analyzed CD40L expression in unstimulated lymphocytes from peripheral blood samples of uninfected infants vertically exposed to HIV and subjected to ART. The CD45 PanLeucogating strategy was applied in flow cytometry to analyze the lymphocytes of 41 cases and 64 age-matched infants, taken as control. We found increased CD154 expression on both CD4+ and CD8+ lymphocytes in ART-treated infants, compared with the controls. CD154 was apparently functional, because the expression of CD86 on monocytes was enhanced; moreover, inhibition of the CD40-CD40L interaction produced downmodulation of CD86. From these results, we conclude that CD4+ and CD8+ lymphocytes of HIV-exposed noninfected infants, who have been exposed to antiretroviral drugs in fetal and early life, display enhanced CD154 expression and costimulatory activity.

A combined HIV-1 protein bead array for serology assay and T-cell subset immunophenotyping with a hybrid flow cytometer: a step in the direction of a comprehensive multitasking instrument platform for infectious disease diagnosis and monitoring

BACKGROUND

A new generation of bench-top flow cytometers with digital signal processing to perform suspension array technology (SAT) based bead array assays as well as leukocyte immunophenotyping is now available. These hybrid instruments provide an opportunity for the development of a more cost effective multitasking platform to support infectious disease treatment in resource limited countries.

METHODS

We report the development and testing of two modules compatible with the hybrid flow cytometers. The first module is an eleven HIV-1 protein bead array (PBA) for the detection of circulating antibodies and the second is a cell based T-cell enumeration assay.

RESULTS

The HIV-1 PBA was tested in parallel with two enzyme immunoassays (EIAs) for the detection of plasma antibodies from 4 HIV-1 seroconversion panels and a low antibody titer panel. The PBA as well as the two EIAs performed equally for the detection of antibody positive samples from all seroconversion panels. One antibody positive sample from the low antibody titer panel was missed by the PBA together with one of the two EIAs tested. A parallel analysis of the HIV-1 PBA with Western blot (a confirmatory test for HIV infection) using plasma from nine HIV-1(+) individuals showed that the HIV-1 PBA detected more of the gp41 and gp120 antibody positive samples. Preliminary CD4 T-cell immunophenotyping results from 14 HIV(+) and 10 HIV(-) whole blood specimens with the hybrid flow cytometer platform compared well to conventional flow cytometry data.

CONCLUSION

The successful combination of bead and cell based assays on a single hybrid instrument demonstrated the potential utility of a multitasking platform. The results presented are providing groundwork for future development of more cost effective modular architecture for a flexible flow cytometry based platform.

Flow rate calibration. III. The use of stabilized biostandards to calibrate the flow rate and calculate absolute CD4+ T-cell counts

BACKGROUND

We have previously reported a flow rate calibration method for the determination of absolute CD4(+) T-lymphocyte counts that removes the need for the addition of latex beads to each sample. However, a limitation with this approach is that a calibration factor (CF) needs to be applied to adjust for differences in viscosity between latex bead suspensions and biological specimens. We have also demonstrated the value of using stabilized whole blood samples in external quality assessment (EQA) studies; such samples have a stable absolute lymphocyte count for over 1 year, at 4 degrees C. It was successfully demonstrated that this material can be used as a flow rate biocalibration (FRB) material for use as a flow cytometric control to provide a sample with a known CD4(+) T-lymphocyte count. Such material has advantages over latex bead technology as it can act as a full process control as well as having the same matrix and viscosity characteristics as the test material, thus removing the need for a CF.

METHODS

In this study, we have analyzed 268 consecutive normal, abnormal, and HIV(+) samples using FRB, incorporating the PanLeucoGating approach and compared this to the MultiSet method, defined as the predicate.

RESULTS

Percentage similarity statistics revealed the following: 0-3,000 CD4(+) cells/mul mean percentage difference (MPD; bias) 1.2%, 95% CI of 5.6-8%; 0-200 CD4(+) cells/microl MPD of 1.25%, 95% CI of 11.63-14.13%; 201-500 CD4(+) cells/microl MPD of 1%, 95% CI of 4.6-6.6%.

DISCUSSION

This study demonstrates that stabilized whole blood can be used for FRB. It has the advantage of being a full process control, in addition to costing less than latex beads with highly comparable results. As bench top flow cytometers are extremely stable, this is a low cost and robust alternative to bead based methods for generating absolute CD4 counts.

T-lymphocyte reconstitution following rigorously T-cell-depleted versus unmodified autologous stem cell transplants

We compared the kinetics of T-cell recovery after extensive ex vivo and in vivo T-cell depleted autologous stem cell transplantation (SCT) for multiple sclerosis (MS; n=8) with unmodified SCT for hematological malignancies (HM; n=39). Both patient group showed a very protracted recovery of 'naive' CD4(+), 45R0(-) ( approximately CD45RA(+)) T-cells. Within the 'primed' CD4(+), 45R0(+) T-cells, the 'central memory' cells expressing the CD62L and CD27 markers were the slowest to recover. The repopulating T-cells were highly activated, as shown by increased expression of HLA-DR and the apoptosis marker CD95. The capability of CD4(+) and CD8(+) T-cells to produce IFN-gamma, IL-2 and TNF-alpha had reached normal ranges from 2 months post SCT onwards. Unexpectedly, the kinetics of T-cell recovery between 3 and 12 months post transplant was similar in T-depleted and unmodified SCT. Before SCT, the HM patients showed lymphopenia of all T-cell subsets, upregulated HLA-DR and CD95 expression and increased cytokine responses. We suggest that the similar kinetics of T-cell recovery in the two patient groups may be explained by the susceptibility to apoptosis of the activated CD4(+) T-cells in the autografts of the HM patients. This susceptibility to apoptosis would interfere with a swift and sustained CD4(+) T-cell regeneration post SCT.

Efficacy of Cyto-Chex Blood Preservative for Delayed Manual CD4 Testing Using Dynal T4 Quant CD4 Test Among HIV-Infected Persons in Zambia

BACKGROUND

Manual CD4 tests such as Dynal T4 Quant (Dynabeads, Dynal Biotech, Oslo, Norway) are less expensive alternatives to flow cytometry in resource-limited countries. Whereas blood preservatives have proven useful for stabilizing blood samples to allow delayed CD4 testing by flow cytometry, they have not been verified for manual tests. A method for preservation of blood prior to manual CD4 testing is needed for long-distance transport or sample batching.

METHODS

Blood from HIV-positive Zambian military beneficiaries was mixed (1:1) with Cyto-Chex (Streck Laboratories, La Vista, NE) blood preservative, and the blood was stored at refrigerated, ambient, and incubator (37 degrees C) temperatures prior to Dynabeads CD4 testing at 0, 3, 6, and 9 days after collection. Baseline flow cytometry and Dynabeads testing without preservative were performed for comparison.

RESULTS

Twenty-seven patient samples were analyzed. Dynabeads vs. flow cytometry had a correlation coefficient (r) of 0.84. There was excellent correlation (r = 0.96) between baseline Dynabeads testing and Cyto-Chex-preserved samples. Refrigerated samples showed strong correlation with baseline Dynabeads (r = 0.93-0.95) on days 3, 6, and 9 without decline in CD4 count (P = 0.73). Samples stored at ambient temperature yielded inferior results (r = 0.76-0.81), with a significant decline in CD4 count by day 3 (P < 0.001). The incubator arm had especially poor correlation (r = 0.30-0.49).

CONCLUSIONS

Addition of Cyto-Chex to peripheral blood (1:1) adequately preserves refrigerated blood samples for up to 9 days for subsequent testing with Dynabeads CD4 test. Cyto-Chex, however, cannot be recommended for delayed Dynabeads CD4 testing with storage at 37 degrees C or ambient temperatures in tropical areas similar to the site of this study.

Low cost CD4 enumeration using generic monoclonal antibody reagents and a two-color user-defined MultiSET™ protocol

BACKGROUND

The standard three-tube, three-color flow cytometric method utilizing the TriTEST reagents in conjunction with the MultiSET software commonly used in most laboratories in Thailand for CD4 enumeration is expensive and thus unavailable to most HIV-infected patients. A more affordable method, i.e., the PanLeucogating protocol using only two monoclonal antibody reagents, has been described but requires the use of the CellQUEST software that does not have automatic gating and reporting facilities. We describe a simple protocol that utilizes a two-color user-defined protocol with the automated MultiSET software for the acquisition, analysis, and reporting of CD4 results.

METHODS

A two-color user-defined protocol was set up following instructions in the Becton Dickinson Biosciences MultiSET manual, adhering strictly to the information regarding the Gate and Attractor Hierarchy for analyzing various reagent combinations. This simple two-color user-defined MultiSET software was evaluated using generic monoclonal reagents in comparison with the standard TriTEST/MultiSET protocol.

RESULTS

The two-color user-defined MultiSET software is easy to use. It requires only modification of the original MultiSET program and the results obtained are comparable with those derived from the standard TriTEST/MultiSET protocol.

CONCLUSION

The use of this easy and reliable two-color user-defined MultiSET protocol represents an affordable alternative to CD4 testing in resource-poor settings.

Estimates of eligibility for antiretroviral treatment (ART) and projected ART impact on AIDS mortality among South African educators

The study assessed the proportion of HIV-infected educators that need antiretroviral treatment (ART) according to current criteria, and estimated the impact of ART on AIDS mortality by modelling scenarios with and without access to ART. Specimens for HIV testing were obtained from 17 088 educators and a sub-sample of 444 venous blood specimens from HIV-positive educators was selected for a CD4 cell count analysis. The Spectrum model package was used for estimating AIDS-associated mortality and projecting the impact of ART scenarios. The results of the CD4 cell count analysis in the HIV-positive educator study population showed that 8% had fewer than 100, 22% fewer than 200, 52% fewer than 350, and 72% fewer than 500 CD4 cells/mm3. Based on the proportion of HIV-positive educators with a CD4 cell count < 200 cells/mm3 we estimated that in 2005 approximately 10 700 educators would need ART according to current SA government guidelines. For the baseline scenario without ART the number of AIDS deaths among HIV-infected educators was projected to increase from 1 992 deaths in 2000 to 5 260 in 2010. The number of projected AIDS deaths in the educator study population was estimated to be 4 414 in 2005, with almost 50% of the AIDS deaths occurring in the 35 - 44 age group. The estimates suggest that in 2005 9.1% of the HIV-infected educators, or 1.2% of the total educator population, will be dying of AIDS. By 2010, a reduction of almost 50% in AIDS deaths was estimated for the treatment scenario with 90% ART coverage, compared with the baseline scenario without treatment. The ART impact scenarios illustrate that a relatively high ART coverage would be needed to ensure a substantial impact of ART on HIV/AIDS-associated mortality.

Increased prevalence of severe malaria in HIV-infected adults in South Africa

BACKGROUND

Conflicting reports exist regarding the impact of human immunodeficiency virus (HIV) infection on the risk of severe malaria. We aimed to assess the effect of HIV infection status, advancing immunosuppression, and antimalarial immunity on the severity of malaria.

METHODS

A prospective cohort study was conducted. Consecutive hospitalized adult patients with falciparum malaria were tested for HIV antibodies and to determine CD4+ T cell count. Immunity to malaria was assessed by obtaining a history of childhood residence in an area where malaria is endemic. Patients were assessed for features of severe malaria.

RESULTS

Three hundred thirty-six patients were enrolled in the study, of whom 32 (10%) had severe malaria. The prevalence of HIV infection was 33%, and 111 patients (33%) were nonimmune to malaria. HIV-infected patients complained more frequently about respiratory and abdominal symptoms and less frequently about rigors and headache. Risk factors for severe malaria determined by multivariate analysis included being nonimmune to malaria, having a positive HIV serostatus, having an elevated parasite count, and having an increased white blood cell count. Risk of severe malaria was increased in HIV-infected patients with a CD4+ T cell count of < 200 x 10(6) cells/L (P < or = .001). Nonimmune HIV-infected patients were significantly more likely to have severe malaria (13 [36%] of 36 patients) than were nonimmune non-HIV-infected patients (9 [12%] of 75 patients; odds ratio, 4.15 [95% confidence interval, 1.57-10.97]; P = .003). HIV serostatus did not affect risk of severe malaria in the group from an area with endemicity (5 [7%] of 74 HIV-infected patients had severe malaria, and 5 [3%] of 151 non-HIV-infected patients had malaria; P = .248).

CONCLUSIONS

HIV-infected nonimmune adults are at increased risk of severe malaria. This risk is associated with a low CD4+ T cell count. This interaction is of great public health importance.