Lymphocyte subset enumeration in HIV seronegative and HIV-1 seropositive adults in Dar es Salaam, Tanzania: determination of reference values in males and females and comparison of two flow cytometric methods

Variation of B cell subsets with age in healthy Malawians

Although a number of previous studies have shown that different lymphocyte subsets, including B cells, vary with age, how different B cell subsets vary with age in Malawian population has not been shown before. We recruited Malawian participants of different ages and analyzed their venous blood samples for different B cell subsets. We found that both percentage and absolute counts of B cells varied with age peaking in the 7 to 12 months age group. Proportion of naïve B cells was highest in neonates and decreased with age whereas the percentage of memory B cells was lowest in neonates and increased with age. When we zeroed in on the age band within which the proportion of B cells was highest, both classical and activated memory B cells increased with age and the naïve followed the opposite trend. These results provide additional knowledge in our understanding of the dynamics of B cell subsets in individuals of a specific ethnicity as they age.

Assessment of the AQUIOS flow cytometer - An automated sample preparation system for CD4 lymphocyte PanLeucogating enumeration

Background

Flow cytometry has been the approach of choice for enumerating and documenting CD4-cell decline in HIV monitoring. Beckman Coulter has developed a single platform test for CD4+ T-cell lymphocyte count and percentage using PanLeucogating (PLG) technology on the automated AQUIOS flow cytometer (AQUIOS PLG).

Objectives

This study compared the performance of AQUIOS PLG with the Flowcare PLG method and performed a reference interval for comparison with those previously published.

Methods

The study was conducted between November 2014 and March 2015 at 5 different centres located in Canada; Paris, France; Lyon, France; the United States; and South Africa. Two-hundred and forty samples from HIV-positive adult and paediatric patients were used to compare the performances of AQUIOS PLG and Flowcare PLG on a FC500 flow cytometer (Flowcare PLG) in determining CD4+ absolute count and percentage. A reference interval was determined using 155 samples from healthy, non-HIV adults. Workflow was investigated testing 440 samples over 5 days.

Results

Mean absolute and relative count bias between AQUIOS PLG and Flowcare PLG was −41 cells/µL and −7.8%. Upward and downward misclassification at various CD4 thresholds was ≤ 2.4% and ≤ 11.1%. The 95% reference interval (2.5th – 97.5th) for the CD4+ count was 453–1534 cells/µL and the percentage was 30.5% – 63.4%. The workflow showed an average number of HIV samples tested as 17.5 per hour or 122.5 per 8-hour shift for one technician, including passing quality controls.

Conclusion

The AQUIOS PLG merges desirable aspects from conventional flow cytometer systems (high throughput, precision and accuracy, external quality assessment compatibility) with low technical operating skill requirements for automated, single platform systems.

Virologic and immunologic failure, drug resistance and mortality during the first 24 months postpartum among HIV-infected women initiated on antiretroviral therapy for life in the Mitra plus Study, Dar es Salaam, Tanzania

Background

In the Mitra plus study of prevention of mother-to-child transmission of HIV-1, which included 501 women in Dar es Salaam, Tanzania, triple antiretroviral therapy (ART) was given from late pregnancy throughout breastfeeding up to 6 months postnatally. Here we report findings in a sub-cohort of women with ≤200 CD4cells/μL at enrolment who were continued on ART for life and followed up during 24 months after delivery to determine virologic and immunologic responses, drug resistance and mortality.

Methods

Blood samples for viral load and CD4 counts testing were collected at enrolment and at 3, 6, 12 and 24 months postpartum. HIV drug resistance testing was performed at 12 months. Data analysis included descriptive statistics and multivariate analysis using Generalized Estimated Equations of 73 women with at least two postpartum assessments. The mortality analysis included 84 women who had delivered.

Results

The proportion of women with a viral load ≥400 copies/mL was 97% (71/73) at enrolment, 16% (11/67), 22% (15/69), 61% (36/59) and 86% (48/56) at 3, 6, 12 and 24 months postpartum, respectively. The proportion of women with immunologic failure was 12% (8/69), 25% (15/60) and 41% (24/58) at 6, 12 and 24 months, respectively. At 12 months, drug resistance was demonstrated in 34% (20/59), including 12 with dual-class resistance. Self-report on drug adherence was 95% (64/68), 85% (56/66), 74% (39/53) and 65% (30/46) at 3, 6, 12 and 24 months, respectively. The mortality rate was 5.9% (95% CI 2.5-13.7%) at 24 months. The probability of virologic and immunologic failure was significantly higher among women who reported non-perfect adherence to ART at month 24 postpartum.

Conclusions

Following an initial decline of viral load, virologic failure was common at 12 and 24 months postpartum among women initiated on ART for life during pregnancy because of low CD4 cell counts. A high proportion of viremic mothers also had resistance mutations. However, at 24 months follow-up, the mortality rate was still fairly low. Continuous adherence counseling and affordable means of monitoring of the virologic response are crucial for successful implementation of the WHO Option B+ guidelines to start all HIV-infected pregnant women on ART for life.

Comprehensive reference ranges for hematology and clinical chemistry laboratory parameters derived from normal Nigerian adults

BACKGROUND

Interpretation of laboratory test results with appropriate diagnostic accuracy requires reference or cutoff values. This study is a comprehensive determination of reference values for hematology and clinical chemistry in apparently healthy voluntary non-remunerated blood donors and pregnant women.

METHODS AND FINDINGS

Consented clients were clinically screened and counseled before testing for HIV, Hepatitis B, Hepatitis C and Syphilis. Standard national blood donors' questionnaire was administered to consented blood donors. Blood from qualified volunteers was used for measurement of complete hematology and chemistry parameters. Blood samples were analyzed from a total of 383 participants, 124 (32.4%) males, 125 (32.6%) non-pregnant females and 134 pregnant females (35.2%) with a mean age of 31 years. Our results showed that the red blood cells count (RBC), Hemoglobin (HB) and Hematocrit (HCT) had significant gender difference (p = 0.000) but not for total white blood count (p>0.05) which was only significantly higher in pregnant verses non-pregnant women (p = 0.000). Hemoglobin and Hematocrit values were lower in pregnancy (P = 0.000). Platelets were significantly higher in females than men (p = 0.001) but lower in pregnant women (p =  .001) with marked difference in gestational period. For clinical chemistry parameters, there was no significant difference for sodium, potassium and chloride (p>0.05) but gender difference exists for Bicarbonate (HCO3), Urea nitrogen, Creatinine as well as the lipids (p<0.05). Total bilirubin was significantly higher in males than females (p = 0.000). Significant differences exist for all chemistry parameters between pregnant and non-pregnant women in this study (p<0.05), except Amylase and total cholesterol (p>0.05).

CONCLUSIONS

Hematological and Clinical Chemistry reference ranges established in this study showed significant gender differences. Pregnant women also differed from non-pregnant females and during pregnancy. This is the first of such comprehensive study to establish reference values among adult Nigerians and difference observed underscore the need to establish reference values for different populations.

Reference values for clinical laboratory parameters in young adults in Maputo, Mozambique

Background

Clinical laboratory reference values from North American and European populations are currently used in most Africans countries due to the absence of locally derived reference ranges, despite previous studies reporting significant differences between populations. Our aim was to define reference ranges for both genders in 18 to 24 year-old Mozambicans in preparation for clinical vaccine trials.

Methods

A cross-sectional study including 257 volunteers (102 males and 155 females) between 18 and 24 years was performedat a youth clinic in Maputo, Mozambique. All volunteers were clinically healthy and human immunodeficiency virus, Hepatitis B virus and syphilis negative.Median and 95% reference ranges were calculated for immunological, hematological and chemistry parameters. Ranges were compared with those reported based on populations in other African countries and the US. The impact of applying US NIH Division of AIDS (DAIDS) toxicity tables was assessed.

Results

The immunology ranges were comparable to those reported for the US and western Kenya.There were significant gender differences in CD4⁺ T cell values 713 cells/µL in males versus 824 cells/µL in females (p<0.0001). Hematologic values differed from the US values but were similar to reports of populations in western Kenya and Uganda. The lower and upper limits of the ranges for hemoglobin, hematocrit, red blood cells, white blood cells and lymphocytes were somewhat lower than those from these African countries. The chemistry values were comparable to US values, with few exceptions. The upper limits for ALT, AST, bilirubin, cholesterol and triglycerides were higher than those from the US. DAIDStables for adverse events predicted 297 adverse events and 159 (62%) of the volunteers would have been excluded.

Conclusion

This study is the first to determine normal laboratory parameters in Mozambique. Our results underscore the necessity of establishing region-specific clinical reference ranges for proper patient management and safe conduct of clinical trials.

Experiences on recruitment and retention of volunteers in the first HIV vaccine trial in Dar es Salam, Tanzania - the phase I/II HIVIS 03 trial

Background

Eventual control of HIV/AIDS is believed to be ultimately dependent on a safe, effective and affordable vaccine. Participation of sub-Saharan Africa in the conduct of HIV trials is crucial as this region still experiences high HIV incidences. We describe the experience of recruiting and retaining volunteers in the first HIV vaccine trial (HIVIS03) in Tanzania.

Methods

In this trial enrolled volunteers from amongst Police Officers (POs) in Dar es Salaam were primed with HIV-1 DNA vaccine at months 0, 1 and 3; and boosted with HIV-1 MVA vaccine at months 9 and 21. A stepwise education provision/sensitization approach was employed to eventual recruitment. Having identified a “core” group of POs keen on HIV prevention activities, those interested to participate in the vaccine trial were invited for a first screening session that comprised of provision of detailed study information and medical evaluation. In the second screening session results of the initial assessment were provided and those eligible were assessed for willingness to participate (WTP). Those willing were consented and eventually randomized into the trial having met the eligibility criteria. Voluntary participation was emphasized throughout.

Results

Out of 408 POs who formed the core group, 364 (89.0%) attended the educational sessions. 263 out of 364 (72.2%) indicated willingness to participate in the HIV vaccine trial. 98% of those indicating WTP attended the pre-screening workshops. 220 (85.0%) indicated willingness to undergo first screening and 177 POs attended for initial screenings, of whom 162 (91.5%) underwent both clinical and laboratory screenings. 119 volunteers (73.5%) were eligible for the study. 79 were randomized into the trial, while 19 did not turn up, the major reason being partner/family advice. 60 volunteers including 15 females were recruited during a one-year period. All participated in the planned progress updates workshops. Retention into the schedule was: 98% for the 3 DNA/placebo vaccinations, while it was 83% and 73% for the first and second MVA/placebo vaccinations respectively.

Conclusion

In this first HIV vaccine trial in Tanzania, we successfully recruited the volunteers and there was no significant loss to follow up. Close contact and updates on study progress facilitated the observed retention rates.

Trial registration numbers

ISRCTN90053831 ISRNCT01132976 and ATMR2009040001075080

Lymphocyte subsets: reference ranges in an age- and gender-balanced population of Omani healthy adults

Country-specific reference ranges for adult peripheral blood lymphocyte subsets have been established in a few countries around the world; however, there have been no specific comprehensive studies in the Gulf Cooperation Council (GCC) and Middle East, which investigated age and gender-specific reference ranges. Demographic and environmental factors may contribute to variations in these subsets around the world, and thus there is a great necessity for each country to establish its own reference ranges. Hence, the aim of this study is to establish lymphocyte subsets reference ranges for Omani healthy adults. Total, age, and gender-specific reference ranges were established using four-color flow cytometry analysis with an extensive panel of monoclonal antibodies in 50 healthy adult males and females aged between 18 and 57. Reference values were expressed as median and 95% confidence intervals for T cells-CD3(+) : 76.5 (57-89), CD4(+) : 45 (31-58), CD5(+) : 75 (58-85), CD7(+) : 80 (70-89), CD8(+) : 29.5 (19-43); B cells-CD10(+) : 1 (1-3), CD19(+) : 14 (6-23), CD20(+) : 14 (6-23), and NK cells-CD16(+) : 9 (3-22), CD56(+) : 13 (5-24), CD3(-) /(CD16(+) /CD56(+) ): 7 (3-20). In comparison with other published studies, the lymphocyte subsets reference ranges in healthy Omani adults were similar to those reported in the rest of the world. These observations have important clinical implications in lymphocyte subset analysis in Oman, especially in the management of immunological disorders. The reference ranges established by this study can be adopted as a reference for clinical practice decisions.

Distribution of CD4 Lymphocyte Cells Among Apparently Healthy HIV Seropositive and Seronegative Populations

Background:

CD4 lymphocyte cells are often used as prognostic markers for monitoring the progression of immunosupression such as HIV infection.

Aim:

This study was conducted to assess the distribution of CD4 lymphocytes among apparently healthy human immunodeficiency virus (HIV) seronegative and seropositive populations in a Nigerian state.

Materials and Methods:

A total of 1520 apparently healthy subjects aged 18–64 years, composed of 800 males and 720 females attending some selected health institutions in the state, participated in the study. Ten milliliters of blood was collected from each subject; 5 ml of this was used for HIV antibodies sero-typing while the remaining 5 ml was anticoagulated and used for CD4 lymphocytes level determination. Only samples tested positive both with Capillus and Determine HIV test kits were further differentiated into sero-types with a standard diagnostic HIV test kit. The CD4 lymphocyte levels of all the sample were determined; mean CD4 levels of 205.1±0.09 and 287.4±0.3 cells/μl were recorded among females seropositives and seronagatives respectively. Statistical analysis by the Student t-test showed a significant difference in the mean CD4 lymphocyte count by gender.

Results:

Findings showed a mean CD4 level of 311.7±1.2 cells/μl among seropositive males while 399.3±0.6 cells/μl was recorded among seronegatives (t=5.86). The study also recorded a CD4 lymphocyte range of 232–464 cells/μl among apparently healthy seronegative population in this locality.

Conclusion:

The findings showed a significantly higher mean CD4 lymphocyte count among adult male HIV seronegatives (χ²=9.22) and seropositives (χ²=15.07) than their female counterparts. Further research work using the automation technique is suggested to confirm this new range for monitoring HIV subjects on antiretroviral therapy.

Laboratory expansion to large-scale international HIV preventive vaccine trials

PURPOSE OF REVIEW

The purpose of this article is to describe the requirements for clinical laboratories supporting large-scale multinational trials of prophylactic AIDS vaccine trials and review the progress made.

RECENT FINDINGS

There is an increasing need for laboratories in Africa, Asia and the Caribbean to support internationally initiated and funded clinical trials of preventive HIV vaccine candidates. A number of qualified laboratories are currently supporting AIDS vaccine trials in these regions, although there remains a need to develop capacity further. The standardization of all tests is key in order that data can be pooled and compared across multiple sites and products. Significant progress has been made towards this aim. The recent development of quality programmes including good clinical laboratory practices are key to ensuring data are reliable and meet the requirements of regulatory bodies. In addition, HIV diagnostic tests are being developed to distinguish true HIV infection from vaccine-induced antibodies.

SUMMARY

Significant advances have been made to develop laboratories capable of supporting multinational AIDS vaccine trials.

Cervical cytological changes in HIV-infected patients attending care and treatment clinic at Muhimbili National Hospital, Dar es Salaam, Tanzania

BACKGROUND

Tanzania is among Sub-Saharan countries mostly affected by the HIV and AIDS pandemic, females being more vulnerable than males. HIV infected women appear to have a higher rate of persistent infection by high risk types of human papillomavirus (HPV) strongly associated with high-grade squamous intraepithelial lesions (HSIL) and invasive cervical carcinoma. Furthermore, although HIV infection and cervical cancer are major public health problems, the frequency and HIV/HPV association of cervical cancer and HSIL is not well documented in Tanzania, thus limiting the development of preventive and therapeutic strategies.

METHODS

A prospective unmatched, case-control study of HIV-seropositive, ≥ 18 years of age and consenting non-pregnant patients attending the care and treatment center (CTC) at Muhimbili National Hoospital (MNH) as cases was done between 2005 and 2006. HIV seronegative, non-pregnant and consenting women recruited from the Cervical Cancer Screening unit (CCSU) at ORCI were used as controls while those who did not consent to study participation and/or individuals under < 18 years were excluded. Pap smears were collected for routine cytodiagnosis and P53 immunohistochemistry (IHC). Cervical lesions were classified according to the Modified Bethesda System.

RESULTS

A total of 170 participants from the two centers were recruited including 50 HIV-seronegative controls were from the CCSU. Ages ranged from 20-66 years (mean 40.5 years) for cases and 20-69 years (mean 41.6 years) for controls. The age group 36-45 years was the most affected by HIV (39.2%, n = 47). Cervicitis, squamous intraepithelial lesions (SIL) and carcinoma constituted 28.3% (n = 34), 38.3% (n = 46) and 5.8% (n = 7) respectively among cases, and 28% (n = 14), 34% (n = 17) and 2% (n = 1) for controls, although this was not statistically significant (P-value = 0.61). IHC showed that p53 was not detectable in HPV + Pap smears and cell blocks indicating possible degradation.

CONCLUSIONS

The frequency of SIL and carcinoma appeared to be higher among HIV-infected women on HAART compared to seronegative controls and as expected increased with age. HIV seropositive patients appeared to present earlier with SIL compared to those HIV seronegative suggesting a role of HIV in altering the natural history of HPV infection and cervical lesions. The absence of p53 immunoreactivity in HPV + lesions is indicative of the ability of HPV E6 proteins to interact with the tumor suppressor gene and pave way for viral-induced oncogenesis in the studied Tanzanian women.

Gender effect on in vitro lymphocyte subset levels of healthy individuals

Differences in gender immune response have resulted in differences in immune protection and susceptibility to inflammatory diseases. Cultured peripheral blood mononuclear cells (PBMC) are widely used in immunomodulation studies, yet the influence of gender is usually not considered. We examined the effect of in vitro culture and phytohaemagglutinin (PHA) stimulation on PBMC lymphocyte subsets using flowcytometry. Full blood counts of whole blood showed higher levels of lymphocyte in male subjects. Lymphocyte subsets enumeration revealed higher NK cell counts in males and higher B cells in females. Cultured PBMC resulted in significant increases in B and total T cell percentages among females and NK cells among males. PHA stimulated significantly increased percentages of NK and total T cells in males and total activated T cells (CD69+) in females. Our results showed significant gender differences in lymphocyte subsets in cultured conditions. This may affect experimental outcome.

Population-based biochemistry, immunologic and hematological reference values for adolescents and young adults in a rural population in Western Kenya

Background

There is need for locally-derived age-specific clinical laboratory reference ranges of healthy Africans in sub-Saharan Africa. Reference values from North American and European populations are being used for African subjects despite previous studies showing significant differences. Our aim was to establish clinical laboratory reference values for African adolescents and young adults that can be used in clinical trials and for patient management.

Methods and Findings

A panel of 298, HIV-seronegative individuals aged 13–34 years was randomly selected from participants in two population-based cross-sectional surveys assessing HIV prevalence and other sexually transmitted infections in western Kenya. The adolescent (<18 years)-to-adults (≥18 years) ratio and the male-to-female ratio was 1∶1. Median and 95% reference ranges were calculated for immunohematological and biochemistry values. Compared with U.S-derived reference ranges, we detected lower hemoglobin (HB), hematocrit (HCT), red blood cells (RBC), mean corpuscular volume (MCV), neutrophil, glucose, and blood urea nitrogen values but elevated eosinophil and total bilirubin values. Significant gender variation was observed in hematological parameters in addition to T-bilirubin and creatinine indices in all age groups, AST in the younger and neutrophil, platelet and CD4 indices among the older age group. Age variation was also observed, mainly in hematological parameters among males. Applying U.S. NIH Division of AIDS (DAIDS) toxicity grading to our results, 40% of otherwise healthy study participants were classified as having an abnormal laboratory parameter (grade 1–4) which would exclude them from participating in clinical trials.

Conclusion

Hematological and biochemistry reference values from African population differ from those derived from a North American population, showing the need to develop region-specific reference values. Our data also show variations in hematological indices between adolescent and adult males which should be considered when developing reference ranges. This study provides the first locally-derived clinical laboratory reference ranges for adolescents and young adults in western Kenya.

Prevalence of genotypic resistance to antiretroviral drugs in treatment-naive youths infected with diverse HIV type 1 subtypes and recombinant forms in Dar es Salaam, Tanzania

As human immunodeficiency virus (HIV) diversity may have an impact on both vaccine efficacy and drug resistance, it is important to have knowledge of circulating genetic variants. With widespread use of antiretroviral (ARV) drugs in Africa, one of the major potential challenges is the risk of emergence of ARV drug-resistant HIV strains. This study aimed to determine the circulating HIV subtypes and recombinant forms, as well as the prevalence of ARV drug resistance mutations, among 75 treatment-naive HIV-infected youths in Dar es Salaam, Tanzania. Gag (n = 48), partial pol (n = 44), and partial env (n = 35) sequencing was performed; all three regions were sequenced in 26 samples. Evidence of infection with recombinant viruses was found in 12 (46%) participants; AC recombinants were the most commonly detected and they were identified in six (23%) participants. Of individuals infected with nonrecombinant strains, subtype A was most commonly detected in seven (27%) participants, followed by subtype C detected in six (23%) participants and subtype D detected in one (4%) participant. Among the pol sequences from 44 individuals, three (7%) had resistance to nucleoside reverse transcriptase (RT) inhibitors and four (9%) had nonnucleoside RT inhibitor resistance mutations. Of these, three (7%) individuals were infected with viruses with cross-resistance mutations to both classes of RT inhibitors. These resistant mutations were all associated with drugs currently used in first-line therapy and in the prevention of vertical transmission. This high prevalence of resistance mutations is of considerable concern in apparently drug-naive populations as it may result in treatment failure and the spread of ARV-resistant strains.

Variations in CD4 cell counts among HIV-uninfected and infected women in Uganda and Zimbabwe

We conducted a cross-sectional study with 208 HIV-uninfected and 188 HIV-infected women in Uganda and Zimbabwe to investigate differences in median CD4 counts. Absolute CD4 counts were determined by flow cytometry. Multivariate analyses were used to examine the association of country and HIV-infection status on CD4 counts. Median CD4 counts were significantly lower in Zimbabwe than in Uganda overall (649 and 783 cells/mm(3), P = 0.009) and among HIV-infected women (470 and 614 cells/mm(3), P = 0.003). In separate multivariable models, CD4 counts were significantly lower in Zimbabwe in HIV-uninfected (P = 0.014) and infected (P < 0.001) women, controlling for age, contraceptive method, education and living with partner status. In a model combining HIV-uninfected and infected women, there was no significant interaction between country and HIV infection status (P = 0.344), suggesting that the relationship between country and CD4 count was not significantly modified by HIV infection status. This study reinforces the importance of establishing country-specific reference CD4 levels as CD4 count continues to be used as a key biomarker in clinical decision-making for HIV-infected individuals in sub-Saharan Africa.

Effects of venlafaxine and fluoxetine on lymphocyte subsets in patients with major depressive disorder: a flow cytometric analysis

BACKGROUND

Studies have yielded conflicting results concerning flow cytometric lymphocyte analyses in patients with depression. Data about the effect of antidepressants on lymphocyte subsets are also contradictory. The aim of this study was to determine effects of venlafaxine versus fluoxetine on lymphocyte subsets in depressive patients.

METHODS

Sixty-nine patients diagnosed with major depressive disorder (MDD) according to DSM-IV and 36 healthy controls are included in the study. Sixty-nine patients were randomized to take fluoxetine (FLX) (n=33) or venlafaxine (VEN) (n=36). Serum lymphocyte subsets included CD3, CD4, CD8, CD16/56, CD19, CD45, Anti-HLA-DR which were measured by flow cytometric analyses at baseline and 6 weeks after the start of treatment. The severity of depression was evaluated with Hamilton rating scale for depression.

RESULTS

At baseline, patients with MDD had significantly lower CD16/56 ratio and higher CD45 ratio compared to the controls. Although numerically higher in the VEN treated patients, treatment response rates between the FLX (53%) and the VEN (75%) groups were not different statistically. CD45 values decreased significantly in the VEN group at the end of the 6 week treatment period whereas no difference was observed in the FLX group. By the 6th week, treatment responders showed a significantly higher CD16/56 ratio than non-responders. Baseline severity of depression and anxiety was positively correlated with baseline CD45 ratio and negatively correlated with baseline CD16/56 ratio. We did not observe consistent changes in the absolute number of circulating B or T cells, nor in the helper/inducer (CD4) or suppressor/cytotoxic (CD8) subsets.

CONCLUSIONS

CD16/56 was lower in patients with MDD and increased in treatment responders at 6th week. CD45 ratio was higher in patients with MDD than healthy subjects; it decreased with antidepressant treatment and was positively correlated with the severity of depression. Antidepressant treatment contributes to immune regulation in patients with major depressive disorder.

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.

Normal CD4 T-lymphocyte baseline in healthy HIV-negative pregnant women

The CD4 count is frequently used as a surrogate marker for immune suppression associated with HIV infection and to monitor antiretroviral treatment. The aim of this study is to establish the normal reference values of CD4 count in healthy pregnant women in our environment. Pregnant women attending the antenatal clinic of the University of Maiduguri Teaching Hospital (UMTH) received voluntary counselling and testing for HIV. Those who tested negative had their CD4 count assessed using the cyflow method. Healthy non-pregnant women attending the family planning clinic of the UMTH as well as healthy men coming to donate blood at the blood bank of the same hospital were recruited as controls. A total of 128 pregnant women, 228 non-pregnant women and 185 men were recruited for the study. The mean CD4 count of the pregnant women was 751.41 cells/microl which was significantly lower than the mean CD4 count of 869 cells/microl for the non-pregnant women. Primigravidas had a lower mean CD4 count than both multiparas and grandmultiparas. Similarly, the mean CD4 count was higher in the first trimester than in the later parts of pregnancy. There was no significant difference in the mean CD4 count across all age groups. There is a slight fall in the mean CD4 count in pregnancy, which is more in the first trimester of pregnancy and in primigravidas. This should not affect the reference values for the initiation of antiretroviral drugs in pregnancy.

CLSI-derived hematology and biochemistry reference intervals for healthy adults in eastern and southern Africa

BACKGROUND

Clinical laboratory reference intervals have not been established in many African countries, and non-local intervals are commonly used in clinical trials to screen and monitor adverse events (AEs) among African participants. Using laboratory reference intervals derived from other populations excludes potential trial volunteers in Africa and makes AE assessment challenging. The objective of this study was to establish clinical laboratory reference intervals for 25 hematology, immunology and biochemistry values among healthy African adults typical of those who might join a clinical trial.

METHODS AND FINDINGS

Equal proportions of men and women were invited to participate in a cross sectional study at seven clinical centers (Kigali, Rwanda; Masaka and Entebbe, Uganda; two in Nairobi and one in Kilifi, Kenya; and Lusaka, Zambia). All laboratories used hematology, immunology and biochemistry analyzers validated by an independent clinical laboratory. Clinical and Laboratory Standards Institute guidelines were followed to create study consensus intervals. For comparison, AE grading criteria published by the U.S. National Institute of Allergy and Infectious Diseases Division of AIDS (DAIDS) and other U.S. reference intervals were used. 2,990 potential volunteers were screened, and 2,105 (1,083 men and 1,022 women) were included in the analysis. While some significant gender and regional differences were observed, creating consensus African study intervals from the complete data was possible for 18 of the 25 analytes. Compared to reference intervals from the U.S., we found lower hematocrit and hemoglobin levels, particularly among women, lower white blood cell and neutrophil counts, and lower amylase. Both genders had elevated eosinophil counts, immunoglobulin G, total and direct bilirubin, lactate dehydrogenase and creatine phosphokinase, the latter being more pronounced among women. When graded against U.S. -derived DAIDS AE grading criteria, we observed 774 (35.3%) volunteers with grade one or higher results; 314 (14.9%) had elevated total bilirubin, and 201 (9.6%) had low neutrophil counts. These otherwise healthy volunteers would be excluded or would require special exemption to participate in many clinical trials.

CONCLUSIONS

To accelerate clinical trials in Africa, and to improve their scientific validity, locally appropriate reference ranges should be used. This study provides ranges that will inform inclusion criteria and evaluation of adverse events for studies in these regions of Africa.

Immunohaematological reference values in human immunodeficiency virus-negative adolescent and adults in rural northern Tanzania

Background

The amount of CD4 T cells is used for monitoring HIV progression and improvement, and to make decisions to start antiretroviral therapy and prophylactic drugs for opportunistic infections. The aim of this study was to determine normal reference values for CD4 T cells, lymphocytes, leucocytes and haemoglobin level in healthy, HIV negative adolescents and adults in rural northern Tanzania.

Methods

A cross sectional study was conducted from September 2006 to March 2007 in rural northern Tanzania. Participants were recruited from voluntary HIV counselling and testing clinics. Patients were counselled for HIV test and those who consented were tested for HIV. Clinical screening was done, and blood samples were collected for CD4 T cell counts and complete blood cell counts.

Results

We enrolled 102 participants, forty two (41.2%) males and 60 (58.8%) females. The mean age was 32.6 ± 95% CI 30.2–35.0. The mean absolute CD4 T cell count was 745.8 ± 95% CI 695.5–796.3, absolute CD8 T cells 504.6 ± 95% CI 461.7–547.5, absolute leukocyte count 5.1 ± 95% CI 4.8–5.4, absolute lymphocyte count 1.8 ± 95% CI 1.7–1.9, and haemoglobin level 13.2 ± 95% CI 12.7–13.7. Females had significantly higher mean absolute CD4 T cell count (p = 0.008), mean absolute CD8 T cell count (p = 0.009) and significantly lower mean haemoglobin level than males (p = 0.003)

Conclusion

Immunohaematological values found in this study were different from standard values for western countries. Females had significantly higher mean CD4 T cell counts and lower mean haemoglobin levels than males. This raises the issue of the appropriateness of the present reference values and guidelines for monitoring HIV/AIDS patients in Tanzania.

Reference ranges for the clinical laboratory derived from a rural population in Kericho, Kenya

The conduct of Phase I/II HIV vaccine trials internationally necessitates the development of region-specific clinical reference ranges for trial enrollment and participant monitoring. A population based cohort of adults in Kericho, Kenya, a potential vaccine trial site, allowed development of clinical laboratory reference ranges. Lymphocyte immunophenotyping was performed on 1293 HIV seronegative study participants. Hematology and clinical chemistry were performed on up to 1541 cohort enrollees. The ratio of males to females was 1.9:1. Means, medians and 95% reference ranges were calculated and compared with those from other nations. The median CD4+ T cell count for the group was 810 cells/microl. There were significant gender differences for both red and white blood cell parameters. Kenyan subjects had lower median hemoglobin concentrations (9.5 g/dL; range 6.7-11.1) and neutrophil counts (1850 cells/microl; range 914-4715) compared to North Americans. Kenyan clinical chemistry reference ranges were comparable to those from the USA, with the exception of the upper limits for bilirubin and blood urea nitrogen, which were 2.3-fold higher and 1.5-fold lower, respectively. This study is the first to assess clinical reference ranges for a highland community in Kenya and highlights the need to define clinical laboratory ranges from the national community not only for clinical research but also care and treatment.

Reference ranges for the clinical laboratory derived from a rural population in Kericho, Kenya

The conduct of Phase I/II HIV vaccine trials internationally necessitates the development of region-specific clinical reference ranges for trial enrolment and participant monitoring. A population based cohort of adults in Kericho, Kenya, a potential vaccine trial site, allowed development of clinical laboratory reference ranges. Lymphocyte immunophenotyping was performed on 1293 HIV seronegative study participants. Hematology and clinical chemistry were performed on up to 1541 cohort enrollees. The ratio of males to females was 1.9∶1. Means, medians and 95% reference ranges were calculated and compared with those from other nations. The median CD4+ T cell count for the group was 810 cells/µl. There were significant gender differences for both red and white blood cell parameters. Kenyan subjects had lower median hemoglobin concentrations (9.5 g/dL; range 6.7–11.1) and neutrophil counts (1850 cells/µl; range 914–4715) compared to North Americans. Kenyan clinical chemistry reference ranges were comparable to those from the USA, with the exception of the upper limits for bilirubin and blood urea nitrogen, which were 2.3-fold higher and 1.5-fold lower, respectively. This study is the first to assess clinical reference ranges for a highland community in Kenya and highlights the need to define clinical laboratory ranges from the national community not only for clinical research but also care and treatment.

Prevention of mother-to-child transmission of HIV-1 through breast-feeding by treating infants prophylactically with lamivudine in Dar es Salaam, Tanzania: the Mitra Study

OBJECTIVE

To investigate the possibility of reducing mother-to-child transmission (MTCT) of HIV-1 through breast-feeding by prophylactic antiretroviral (ARV) treatment of the infant during the breast-feeding period.

DESIGN

An open-label, nonrandomized, prospective cohort study in Tanzania (Mitra).

METHODS

HIV-1-infected pregnant women were treated according to regimen A of the Petra trial with zidovudine (ZDV) and lamivudine (3TC) from week 36 to 1 week postpartum. Infants were treated with ZDV and 3TC from birth to 1 week of age (Petra arm A) and then with 3TC alone during breast-feeding (maximum of 6 months). Counseling emphasized exclusive breast-feeding. HIV transmission was analyzed using the Kaplan-Meier survival technique. Cox regression was used for comparison with the breast-feeding population in arm A of the Petra trial, taking CD4 cell count and other possible confounders into consideration.

RESULTS

There were 398 infants included in the transmission analysis in the Mitra study. The estimated cumulative proportion of HIV-1-infected infants was 3.8% (95% confidence interval [CI]: 2.0 to 5.6) at week 6 after delivery and 4.9% (95% CI: 2.7 to 7.1) at month 6. The median time of breast-feeding was 18 weeks. High viral load and a low CD4 T-cell count at enrollment were associated with transmission. The Kaplan-Meier estimated risk of HIV-1 infection at 6 months in infants who were HIV-negative at 6 weeks was 1.2% (95% CI: 0.0 to 2.4). The cumulative HIV-1 infection or death rate at 6 months was 8.5% (95% CI: 5.7 to 11.4). No serious adverse events related to the ARV treatment of infants occurred. The HIV-1 transmission rate during breast-feeding in the Mitra study up to 6 months after delivery was more than 50% lower than in the breast-feeding population of Petra arm A (relative hazard=2.61; P=0.001; adjusted values). The difference in transmission up to 6 months was significant also in the subpopulation of mothers with CD4 counts>or=200 cells/microL.

CONCLUSIONS

The rates of MTCT of HIV-1 in the Mitra study at 6 weeks and 6 months after delivery are among the lowest reported in a breast-feeding population in sub-Saharan Africa. Prophylactic 3TC treatment of infants to prevent MTCT of HIV during breast-feeding was well tolerated by the infants and could be a useful strategy to prevent breast milk transmission of HIV when mothers do not need ARV treatment for their own health.

Slow progression of HIV-1 infection in a cohort of antiretroviral naïve hotel workers in Dar es Salaam, Tanzania as defined by their CD4 cell slopes

Data on slow progression following HIV-1 infection in Africa are sparse. From a study on the natural history of HIV-1 infection in Dar es Salaam, Tanzania, an analysis of immunological and clinical data from 237 HIV-1 seropositive individuals was performed. Annual CD4 cell determinations were carried out by flow cytometry. None was on antiretroviral treatment. CD4+ cell slopes were obtained by fitting a linear regression model. A study population of 50 individuals with >3 CD4 cell determinations and followed for >5 y had a mean follow-up of 72.7 months, and mean 5.7 CD4+ cell determinations. With a criterion of maintaining a CD4 cell count >or=500 cells/ml, 8 of the 50 (16.0%) were long-term non-progressors (LTNP). With a definition of maintaining a CD4+ cell slope <or=-10 (a loss of 10 or less cells per y), 13 (26.0%) were long-term slow progressors (LTSP). 11 of them (84.6%) had a baseline CD4 cell count <500 cells/microl and 5(38.5%) had a baseline CD4 cell count less than 350 cells/microl. An analysis of the selection bias introduced during slope determination is presented. With no selection, 24 (23.3%) would have documented slow CD4 progression among those enrolled for 5 or more y regardless of CD4 determinations.

Laboratory reference values for healthy adults from southern Tanzania

OBJECTIVES

To define and discuss reference ranges for commonly determined laboratory parameters in healthy adults from southern Tanzania.

METHODS

A population-based sample of adult volunteers from Mbeya, Tanzania, who were not HIV positive or showing signs and symptoms of other diseases, participated in this study. We enrolled 145 women and 156 men between 19 and 48 years of age to determine clinical chemistry (CC), haematology and lymphocyte immunophenotyping (LIP) parameters using standard laboratory methods. Medians and nonparametric 95% reference ranges for each parameter were determined and compared with reference ranges from the USA, Europe and from other African countries.

RESULTS

Agreement with ranges from developed countries was poor: for CC values the average concordance was 80.9% and 86.7% with values from two developed countries. Haematology ranges from the USA classified 86.3% of values correctly, whereas ranges from three different sub-Saharan Africa (SSA) sites classified between 82.5% and 94.5% of values correctly. The agreement of LIP reference ranges was 87.5% with values determined in Germany but between 91.7% and 95.8% compared with values determined at other sites in SSA.

CONCLUSION

Clinical reference ranges determined in developed countries are inadequate for use in SSA. Laboratories in this region should either define their own or use values determined under similar conditions. The ranges reported here are more appropriate for use in SSA than ranges determined in developed countries.

Factors associated with CD4 lymphocyte counts in HIV-negative Senegalese individuals

CD4+ lymphocytes are a primary target of the human immunodeficiency virus (HIV), and CD4 counts are one of the factors used to measure disease progression in HIV-positive individuals. CD4 counts vary in uninfected individuals and across populations due to a variety of demographic, environmental, immunological and genetic factors that probably persist throughout the course of HIV infection. This study sought to determine reference levels and identify factors that influence lymphocyte counts in 681 HIV-uninfected adults in Senegal, where residents are exposed to a variety of infectious diseases and other conditions that may affect CD4 counts. Lymphocyte counts were assessed in commercial sex workers, symptomatic men and women presenting to the University of Dakar infectious disease clinic for out-patient care and women seeking family planning services. CD4 and CD3 lymphocyte counts differed between the four study groups (P < 0.01). Men had the lowest mean CD4 count (711.6 cells/microl), while commercial sex workers had the highest levels (966.0 cells/microl). After adjustment for age and other behavioural and clinical factors, the difference in CD4 counts between the three groups of women did not remain. However, both gender and smoking were associated independently with CD4 counts, as men maintained lower mean CD4 counts (beta = -156.4 cells/microl, P < 0.01) and smokers had higher mean CD4 counts (beta = 124.0 cells/microl, P < 0.01) than non-smokers in multivariable analyses. This study is the first to explore factors that may influence CD4 levels in Senegal and to estimate baseline CD4 levels among HIV-negatives, information that may guide clinicians in interpreting CD4 counts.

Immunohematological reference values for healthy adults in Burkina Faso

Reference ranges for peripheral blood lymphocyte subsets were generated for 186 healthy adults in Burkina Faso using single-platform flow cytometry. CD4(+) T-cell counts ranged from 631 to 1,696 cells microl(-1); they were lower in males (n = 97) than in females (n = 89), whereas natural killer cell counts were higher.

The impact of cirrhosis on CD4+ T cell counts in HIV-seronegative patients

BACKGROUND

Studies of the progression liver fibrosis in human immunodeficiency virus (HIV) and hepatitis C virus-coinfected patients suggest that cirrhosis is associated with immunosuppression, as measured by low absolute CD4(+) T cell counts. However, we hypothesized that, in patients with advanced liver disease, low CD4(+) T cell counts may occur secondary to portal hypertension and splenic sequestration, regardless of the presence or absence of HIV infection.

METHODS

Sixty HIV-seronegative outpatients with cirrhosis were enrolled during the period 2001-2003 in a prospective, cross-sectional study of the association between liver disease and CD4(+) T cell counts and percentages. Demographic characteristics, liver disease-related characteristics, and laboratory results--including CD4(+) T cell parameters--were collected.

RESULTS

A total of 39 patients (65%) had a low CD4(+) T cell count; 26 patients (43%) and 4 patients (7%) had CD4(+) T cell counts <350 and <200 cells/mm(3), respectively. Abnormal CD4(+) T cell counts were associated with splenomegaly (P=.03), thrombocytopenia (P=.002), and leukopenia (P<.001). The percentage of CD4(+) T cells was normal in 95% of patients who had a low absolute CD4(+) T cell count. CD4(+) T cell counts were significantly lower among cirrhotic patients than among 7638 HIV-seronegative historic control subjects without liver disease.

CONCLUSIONS

Cirrhosis is associated with low CD4(+) T cell counts in the absence of HIV infection. Discordance between low absolute CD4(+) T cell counts and normal CD4(+) T cell percentages may be attributable to portal hypertension and splenic sequestration. Our findings have significant implications for the use and interpretation of absolute CD4(+) T cell counts in HIV-infected patients with advanced liver disease.

Reference values of CD4 T lymphocytes in human immunodeficiency virus-negative adult Nigerians

A cross-sectional study that involved secondary analysis of data collected from 681 pregnant women and 183 miners (94 men and 89 women; ratio of men to women, 1:0.95) in Jos, Nigeria, was carried out to determine the reference ranges for CD4(+)-cell counts in healthy HIV-negative adult Nigerians. The main results of interest were CD4(+)-cell counts and odds ratios (ORs) of low CD4(+)-cell counts, defined as below 350 cells per microl. CD4(+)-cell counts were similar in men and nonpregnant women, with a mean (standard deviation) of 828 (203) cells per microl, but pregnant women had a lower value of 771 (250) cells per microl. None of the factors assessed was related to the odds of having a low CD4(+)-cell count among men and nonpregnant women, but age, age of marriage, and alcohol usage were significant predictors in pregnant women. Compared to pregnant women less than 20 years old, older women had significantly lower odds of a low CD4(+)-cell count (ORs were 0.06 for women aged 20 to 29 years and 0.22 for those aged 30 to 39 years). When compared with those pregnant women who were married before 20 years of age, those who married at 20 to 29 years and 30 to 39 years had odds ratios of 6.41 and 9.40, respectively. Previous alcohol use was also associated with low CD4(+)-cell counts (OR, 5.15). The 95% confidence interval for CD4(+)-cell counts in healthy adult Nigerians is 547 to 1,327 cells per microl, and this is the first time this has been determined.

Mortality During the First 24 Months After Delivery in Relation to CD4 T-Lymphocyte Levels and Viral Load in a Cohort of Breast-Feeding HIV-1-Infected Women in Dar es Salaam, Tanzania

The objective of this study was to analyze the mortality during the first 24 months after delivery in relation to CD4 T-lymphocyte levels and viral load at enrollment (36 weeks of gestation) in a cohort of HIV-1-seropositive breast-feeding women at the Dar es Salaam site of the multicenter Petra trial (a mother-to-child HIV-1 transmission intervention trial using antiretroviral therapy). Antiretroviral treatment was not available in this setting apart from the short treatment given within the trial around delivery to prevent mother-to-child transmission of HIV. T-lymphocyte subsets were determined by flow cytometry. Plasma HIV-1 RNA was quantified by the Amplicor HIV-1 RNA Monitor v 1.5 assay. Mortality after delivery was analyzed using the life-table technique and Cox regression. The analysis included 266 mothers. The CD4 cell counts at enrollment were <200 cells/mm in 14.5% of the mothers. The viral load at enrollment was >100,000 RNA copies/mL in 33.6% of the mothers. The mortality 24 months after delivery was 6.7% (95% CI = 3.1-10.1%). The mortality 24 months after delivery was 29.9% (95% CI = 13.1-46.9%) for mothers with <200 CD4 cells/mm at enrollment, 3.3% (95% CI = 0-6.6%) for mothers with 200-499 CD4 cells/mm, 2.9% (95% CI = 0-7.1%) for mothers with >500 CD4 cells/mm (P = 0.0000), 15.0% (95% CI = 6.6-23.4%) for mothers with viral load >100,000 copies/mL at enrollment, and 2.8% (95% CI = 0-5.6%) for mothers with viral load <100,000 copies/mL (P = 0.0000). In the multivariate analysis CD4 cell counts and viral load were both independent risk factors for mortality (P < 0.001 and P = 0.004, respectively). In conclusion, the mortality was high among women with severe immunosuppression or high viral load at enrollment, but not in the rest of the women. CD4 lymphocyte count in late pregnancy was a better predictor of death within 2 years than was viral load. The results support the World Health Organization recommendation to initiate antiretroviral treatment in resource-limited settings in HIV-1-infected adults with CD4 cell counts <200/mm and show that this is appropriate also among perinatal women.

Viral dynamics and CD4+ T cell counts in subtype C human immunodeficiency virus type 1-infected individuals from southern Africa

Defining viral dynamics in natural infection is prognostic of disease progression and could prove to be important for vaccine trial design as viremia may be a likely secondary end point in phase III HIV efficacy trials. There are limited data available on the early course of plasma viral load in subtype C HIV-1 infection in Africa. Plasma viral load and CD4+ T cell counts were monitored in 51 recently infected subjects for 9 months. Individuals were recruited from four southern African countries: Zambia, Malawi, Zimbabwe, and South Africa and the median estimated time from seroconversion was 8.9 months (interquartile range, 5.7-14 months). All were infected with subtype C HIV-1 and median viral loads, measured using branched DNA, ranged from 3.82-4.02 log10 RNA copies/ml from 2-24 months after seroconversion. Viral loads significantly correlated with CD4+ cell counts (r=-0.5, p<0.0001; range, 376-364 cells/mm3) and mathematical modeling defined a median set point of 4.08 log10 (12 143 RNA copies/ml), which was attained approximately 17 months after seroconversion. Comparative measurements using three different viral load platforms (bDNA, Amplicor, and NucliSens) confirmed that viremia in subtype C HIV-1-infected individuals within the first 2 years of infection did not significantly differ from that found in early subtype B infection. In conclusion, the course of plasma viremia, as described in this study, will allow a useful baseline comparator for understanding disease progression in an African setting and may be useful in the design of HIV-1 vaccine trials in southern Africa.

Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.

Rate of decline of absolute number and percentage of CD4 T lymphocytes among HIV-1-infected adults in Dar es Salaam, Tanzania

OBJECTIVE

To determine the rate of decline of CD4 T lymphocytes among HIV-1-infected individuals.

DESIGN AND SETTING

A prospective open cohort study of workers in three hotels in Dar es Salaam.

METHODS

The workers were seen yearly during the study. CD4 T lymphocyte counts were determined using flow cytometry. The CD4 T-lymphocyte slopes were determined using a linear regression model.

RESULTS

During the 9-year study period 682 subjects were selected for lymphocyte subset determinations. Of these, 94 HIV-1-seroprevalent (72%), 77 HIV-1-seroincident (67%) and 325 seronegative (75%) individuals had three or more CD4 T-cell determinations, and were used for calculations of CD4 cell slopes with a mean follow-up period of 71.4, 52.9 and 86.0 months, respectively. The median yearly decline of the CD4 T-lymphocyte counts and percentages among seroprevalent individuals was -21.5 cells/microl and -1.3%; among the seroincident individuals the median decline was -22.0 cells/microl and -1.5%. In seroincident individuals the mean duration to a CD4 T-lymphocyte level corresponding to a definition of AIDS was 13.3 years or 11.8 years for CD4 cell counts or percentages, respectively. HIV-1-seropositive subjects who died had significantly steeper CD4 cell slopes than those who survived.

CONCLUSION

The rates of CD4 T-lymphocyte decline in HIV-1-infected individuals in our population are similar to those reported in Europe and north America.

Reference values for peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland

OBJECTIVES

Use of domestic reference values is known to improve the accuracy of flow cytometric analysis by integrating local variation due to race, gender, and age. In the absence of previously published estimates, we now report establishment of reference values for a wide range of peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland and other regions with similar demographic characteristics.

METHODS

A representative sample population was recruited from among well characterized local blood donors (n = 70) and quantitative multiparametric flow cytometry used to estimate absolute and proportional values for a range of T-, B-, and NK-cell subsets, including those associated with activation and maturity. Distribution-free methods were then applied to generate 95% reference values and to estimate the significance of gender and age-related differences.

RESULTS

Reference values were obtained for the absolute and proportional levels of total CD3(+) T cells (536-1787 cells/microL, 54.90-84.03%), helper CD4(+) T cells (309-1139 cells/microL, 32.53-62.88%), cytotoxic CD8(+) T cells (137-823 cells/microL, 11.55-38.60%), activated CD3(+) T cells expressing CD25 (7-94 cells/microL, 0.50-5.95%), CD38 (102-554 cells/microL, 5.98-26.80%), HLA-DR (18-186 cells/microL, 1.25-9.68%) or CD38/HLA-DR (4-52 cells/microL, 0.30-2.30%), activated CD4(+) T cells expressing CD25 (7-52 cells/microL, 0.33-2.80%), CD38 (69-547 cells/microL, 6.13-32.20%), HLA-DR (11-55 cells/microL, 0.80-4.43%) or CD38/HLA-DR (4-22 cells/microL, 0.30-1.35%), activated CD8(+) T cells expressing CD25 (0-12 cells/microL, 0.00-0.69%), CD38 (13-124 cells/microL, 0.93-7.03%), HLA-DR (6-108 cells/microL, 0.33-6.38%) or CD38/HLA-DR (2-47 cells/microL, 0.13-2.68%), naive CD4(+) T cells expressing CD45RA(+)/CD62L(+) (84-761 cells/microL, 9.48-41.88%), naive CD8(+) T cells expressing CD45RA(+)/CD62L(+) (42-360 cells/microL, 3.68-19.23%), memory CD4(+) T cells expressing CD45RO(+) (247-807 cells/microL, 16.50-42.15%), memory CD8(+) T cells expressing CD45RO(+) (72-377 cells/microL, 3.78-22.80%), B-cells expressing CD19 (72-460 cells/microL, 4.70-19.13%) or CD20 (66-529 cells/microL, 4.63-21.00%), total CD3(-)/(CD16(+)/CD56(+)) NK-cells (77-427 cells/microL, 5.35-30.93%), and activated NK-cells expressing CD25 (0-10 cells/microL, 0-0.50%) or HLA-DR (3-99 cells/microL, 0.20-7.28%).

CONCLUSION

It is anticipated that availability of localized reference values for an extended range of peripheral blood lymphocyte phenotypes should supplement previously published reference values and enhance the utility of flow cytometric analysis undertaken in Switzerland.