Community Normal Reference Values for CD 3 + , CD 4 + , CD 8 + T Lymphocytes and Leucocytes among Immunocompetent Adults in Coastal Kenya

Background: Studies on the reference values of CD4 and CD3 T cells in healthy individuals have continued to gain significance because of the importance of these immunological markers in the initiation of antiretroviral therapy and prophylactic drugs for opportunistic infections. These ranges tend to vary across populations. The CD4:CD8 ratio is used to measure of how balanced immune function is. Therefore, this study aimed at determining normal reference values for CD4+ and CD3+T-lymphocytes and leucocytes in healthy adults in Coastal Kenya. Methods: A cross-sectional study was carried between May 2015 and February 2016 in Coast General Referral hospital, Tudor, Port-Reitz, Mlaleo, Likoni and Sub-County hospitals. Participants were recruited from voluntary HIV counselling and testing clinics. Patients were counselled for HIV test and those who consented were tested for HIV. They were screened for diseases that potentially cause lymphocyte homeostasis perturbation. CD4+, CD3+ CD8+cells/μl were analyzed using a BD FACSCount flow cytometer (Becton-Dickson, NJ). Results: We enrolled 500 participants, two hundred and forty (48.0%) were males and two hundred and sixty (52.0) females. The mean CD4 cell count was 1054.9 ± 95% CI 1041.2 1068.6 cells/mm, absolute CD8 was 688.4 ± 95% CI 679.1 697.7 cells/mm, absolute CD3 cell count was 1945.1 ± 95% CI 1907.4 1982.2 cells/mm absolute leukocyte count 5.19 ± 95% CI 5.12 5.19, absolute lymphocyte count 1.85 ± 95% CI1.83 1.88 and haemoglobin level 12.76 ± 95% How to cite this paper: Yonge, S.A., Otieno, M.F., Sharma, R.R. and Nteka, S.S. (2019) Community Normal Reference Values for CD3+, CD4+, CD8+T Lymphocytes and Leucocytes among Immunocompetent Adults in Coastal Kenya. Journal of Biosciences and Medicines, 7, 99-114. https://doi.org/10.4236/jbm.2019.71009 Received: August 30, 2018 Accepted: January 11, 2019 Published: January 14, 2019 Copyright © 2019 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access


Introduction
Immunohaematological indices such as leukocyte, lymphocytes and their subsets such as CD3+T cells, CD4+T cells and CD8+T cells play a major role in both cellular and humoral types of immunity.T lymphocyte cells are defined by the expression of CD3+ molecules.The most important cell-surface molecules for identifying T lymphocyte subpopulations have been CD4+, CD8+, and T-cell receptor complex molecules (CD3+, the T-cell receptor α and β chains) [1].
CD4+T cells are the lymphocytes subsets used for monitoring progression of HIV/AIDS infection and they are also used as a surrogate marker for the improvement of HIV/AIDS patients after initiation of ARV [2].Lymphocyte subset may include; Helper T cells (CD4 T cells), Cytotoxic T cells (CTLs or CD8 T-cells), Memory T cells and Regulatory cells (Treg cells).Upon encounter with antigens, CD4 T cells become activated and proliferate rapidly secreting cytokines that send signals and maintain active immune response.On the other hand, CD8+T-cells destroy virally infected cells and tumor cells, and remain inactivated when there is no foreign antigen.In human immunodeficiency virus-1 (HIV-1) infected individuals, lymphocytes (specifically CD4 T-cells) are the viral prime targets.Therefore in these individuals, a CD4+T count provides a picture of immune system competence, with higher CD4 counts typically signifying healthier immune systems [3] [4].Further, CD4+T cell level determines when to start or stop prophylactic drugs for opportunistic infections [5].Less than 350 cells/μl is considered a threshold for starting ART in HIV-positive patients without other indications in many high-income countries [6] [7] although not all [8] and some commentators argue that with newer, safer antiretrovirals, there should be commencement of therapy at a higher threshold of CD4+T count [9].Similar levels of cut-off are encouraged for low-income countries where feasible [10] despite some evidence that treatment may be delayed further without increasing the risk of AIDS related events [11] [12].
Reference ranges that are currently used in Kenya are derived from data ob-  [20] [21], exercise, cormobid conditions and diurnal variation [22] [23] [24], in addition to variations caused by methodological differences.Averagely, healthy African and Asian populations have been shown to have lower CD4 lymphocyte counts than counts than their western European and Caucasian counterparts [25]- [33].The pattern of lymphocyte generation has been shown to effect the levels of circulating lymphocytes in males, females and individuals of different ages.The pattern of T lymphocyte generation in aging has been associated with dynamic changes in thymic and extrathymic functions along developmental steps from cells to mature cells [34].Increased absolute numbers of peripheral blood CD4+T cells in females compared to males have been reported [35].This is perhaps due to androgens which accelerate thymocytes apoptosis and subsequently influence T cell repertoire with males tending to have less CD4+T cells than females [36] [37].This necessitates the importance of establishing local immunological reference values (CD3 and CD4+T cells for local Kenyan population).The study provides ranges specific for males and females of different age groups.

Haematological Assay
Complete blood cell counts were done using Sysmex Kx-21 (Sysmex Corporation; Kobe Japan).The machine automatically dilutes a whole-blood sample, lyses, counts and gives a printout result of absolute numbers of leucocytes (expressed as number of cells × [10 9 ] per liter), erythrocytes (number of cells × [10 12 ] per liter), platelets (number of cells × [10 9 ] per liter), lymphocytes (number of cells × [10 9 ] per liter), mononuclear cells (number of cells × [10 9 ] per liter), granulocytes (number of cells × [10 9 ] per liter) and haemoglobin (grams per decilitre).The quality and accuracy of the technique and the machine was assessed every six months.

Quality control
The FACSCaliber was calibrated and reconfirmed daily using the BD Caliber the BD Calibrate beads and BD-FACS Comp soft-ware, version 2.0 for setting the photomultiplier tube voltages, setting the fluorescence compensation and checking instrument sensitivity before use.The CD45 versus the side scatter (SSC) dot plot was visually inspected to make sure they appear as a bright compact cluster, with low SSC.

Screening for Malnutrition
All participants were assessed for malnutrition using body mass index (BMI).
Normal nutrition status was defined as BMI > 18.5/kg/m

Data Management and Analysis
Completed questionnaires were coded and doubled entered in computer software Epi-data version 13.1.Cross-checking and data cleaning was done.The data was the transferred to SPSS version 20.0 for analysis.Non parametric reference range determination was employed by estimating the 2.5 and 7.5 percentile [39].The significance of differences between the mean absolute counts and percentages of the Lymphocyte subsets were estimated using the Analysis of Variance (ANOVA) and T-test.Multiple comparisons were done using Tukey's test.Correlation analysis was applied in determining the relationship between lymphocyte subset levels and age.

Ethical Issues
The protocol was approved by Kenyatta University Ethical Review Committee.
Clearance was also obtained from respective district health authorities and hospital administrations.The purpose of the study was explained participants in English, Kiswahili or local language before written consent was sought.The study was conducted in accordance with the declaration of Helsinki.Those participants, who had HIV infection, were referred to the HIV care and treatment Journal of Biosciences and Medicines clinic for further management after counseling.Female participants who were reactive for hcG test were referred to antenatal clinic for better care.

Baseline Characteristics of the Study Participants
Among the 500 individuals between the ages 18 -55 years, 48.0% (240) were males and 52.0%(260) were females.Their blood samples were analysed for CD3, CD4 and CD8 lymphocyte subset for establishment of reference ranges.
Changes in age influenced the subset values marginally in both sexes.With the advancement of age, the CD4 mean counts decreased consistently both males and females though there was a slight increase in males age between 41 -50 years.However, the age dependent changes did not achieve the statistical significance.Women had comparatively higher CD4 mean counts than their male counterparts.The difference was statistically insignificant.On the other hand, males had higher CD8 mean counts compared to females (710.9 ± 113.8 cells/mm 3 and 667.7 ± 93.6 cells/mm 3 ) respectively.The difference again was again statistically insignificant.However, significantly higher mean CD4/CD8 ratios were found in females as compared to males, 1.42 ± 0.17 cells/mm 3 and 1.69 ± 0.49 cells/mm 3 (p < 0.05).In both the sexes, the CD4 mean counts were always higher than the CD8 mean counts irrespective of age (Table 1).

Immunohaematological Reference Values in Human
Immunodeficiency Virus Negative Patients.
The mean CD4+T count in males and females combined was 1054.9 ± 156.1 cells/mm

Males and Females with Lower than Normal Values of CD4 T Cells, Leukocytes, Lymphocytes and Body Mass Index
The mean absolute leukocytes cells in both males and females was 5.  significant statistical difference between males and females with regards to the nutritional status (χ 2 = 76.3, df = 1, p > 0.05).There was no significant association between nutritional status with any of the immunohaematological parameters like CD4+T cells and CD8+T cells and lymphocytes (p > 0.05) but there was association between BMI and leukocytes (p < 0.05).Significant statistical differences was observed in the absolute count means of the lymphocytes in males and females (p < 0.05).There was association between different age-groups and immunohaetological parameters like CD4+T cells (p < 0.05) and CD8+T cells (p < 0.05) (Table 3).

Haematological Reference Ranges in Immunocompetent Individuals
Men had higher Haematocrit, erythrocyte counts, white blood cells counts, platelet counts and neutrophil percentage than women (p < 0.05).Women had higher platelet and neutrophils counts (Table 4).

Discussion
In this study, the mean immunohematological reference values in healthy subjects for CD4+T and CD8+T counts was 1054.9 ± 156.1 cells/mm 3 and 998.7 ± 127.1 cells/mm 3 respectively.Our values were also higher than a number of reports in some countries.For instance, mean CD4 T cell values of 870.7 and 865 cells/μl have been reported among HIV seronegative individuals in Senegal and India, respectively [40] [41].However, the mean CD4 T cells of 1067 cells/μl reported in eastern Ghana by Ampofo et al. [42] is higher than our findings.This may not necessarily mean that Ghanaians have higher counts than Kenyans because the sample size for their study was just two hundred and fourty nine (249).
The study also found that females had significantly higher counts of absolute CD4+T cells and absolute CD8+T cells than males.This findings concur with earlier study done in Tanzania to determine gender difference in CD4 T cells, which showed that males were more likely to have CD4 T cells < 500 cells/mm 3 [33].This was probably due to biological factors.It has been speculated that gender and age-related variations within the immune system parameters may contribute to the pathogenesis of several gender and age-related diseases such as autoimmune disorders in female patients [43] [44] [45].Diurnal variation, however, cannot explain the significant gender difference observed in this study, as all the samples were collected between 9.00 am to 11.00 am.While smoking was also reported to be associated with higher CD4+T count, this could not be the reason for the difference as all female subjects in the present study were nonsmokers.Sex hormone effect could be the possible explanation for the observed gender difference in CD4+T cell count, as the circulating lymphocytes have receptors for androgens and oestrogens [46].These variations in CD4+T cells have been shown to be associated with ethnicity, gender, diet, geographical area as well as being dependent on genetic and environmental factors.Further, it has been shown that there are gender differences in the generation of CD8 cells during HIV-1 infection, due to increased immune activation compared to men [47].Females had significantly lower haemoglobin levels than males in our study.This is similar to findings in North America, Europe and Asia.Overall we found low haemoglobin levels compared to European values and the standard reference haemoglobin values.This can be partly explained by low dietary intake of food rich in iron and vitamins, which is the commonest causes of low haemoglobin levels in Kenya.
The absolute T lymphocytes mean, median, and the 95% normal reference interval value for the current study were also greater than the studies conducted from Switzerland by Bisset et al. [48], Shanghai, Chin [49] and Asian population [50].These differences could be on our apparently healthy study population where they used only blood donors especially in Asian population and Switzerland studies.In our study we used large sample size compared to the other studies.CD3 and CD4 T cells did not correlate directly with age.This agrees with previous studies in China and India that found no significant association of CD4 T cell values with age, but disagrees with a similar study in Nigeria among children [51] [48].In this study the lymphocyte subsets in the different age groups revealed no significant differences.It is however well known that the pattern of T lymphocyte generation with age originates from dynamic changes in thymic as well as extrathymic functions, along with sequential developmental steps from stem cell to ultimately mature cells [52].The finding of significant gender differences for the RBC parameters (erythrocytes, hemoglobin, and hematocrit) agrees with the well-established fact that males have higher values for erythrocytes, hemoglobin, and hematocrit than females, partly due to the influence of the hormone androgen on erythropoiesis and also due to menstrual loss.
Significant differences between the genders with regard to WBC and platelet counts were observed in this study (p < 0.05).The general absence of gender differences for WBC counts disagrees with other reports [53] [54].A study done Saudi Arabia showed a higher percentage and number of CD8+T cells (p < 0.01) and a decreased CD4/CD8 ratio (p < 0.02) compared with the Caucasian controls.Male population had a significantly lower percentage and number of activated T cells (p < 0.05) [55].

Conclusion
Immunohaematological markers found in this study were different from the standard values for the western countries.The ranges are also different from those that are being used currently.Females had significantly higher mean CD4+T and CD8+T cell counts but lower mean haemoglobin level, erythrocytes, white blood cells and platelets than males.Our findings offer useful insight in the CD3 and CD4 T cell reference values of Kenyans and provide important information that will guide future ART decisions and other immune-based therapies.

A
cross-sectional study was conducted in Coastal region of Kenya which has a population of 1,031,266 between May 2015 and February 2016.The study was done at Coast provincial General hospital (CPGH), Mlaleo, Mikindani, Likoni, Portreizt and Tudor Sub County hospitals.These hospitals have HIV voluntary counselling and testing (VCT) services.
Blood samples were tested for HIV antibodies according to the Kenyan national testing algorithm for voluntary counseling and testing.Testing for HIV infection was done by screening serum/plasma by using Determine HIV1/2 (Abott laboratories, Japan co.LTD), Capillus HIV1/2 (The Trinity Biotech, Bray, Co Wicklow, Ireland) and Unigold H1/2 rapid test kits.Concordant positive results were interpreted as positive for HIV antibody.Discordant results were interpreted as inconclusive and the samples were confirmed using ELISA; Enzygnost and anti-HIV 1 + 2 Plus ELISA (Behring, Marburg, Germany) and well-coenzyme HIV recombinant ELISA (Murex, Dartford, England).
Cluster of differentiation 3 and 4 (CD3 & CD4 T) cells were enumerated using a FACSCount flow cytometer (Becton Dickinson Immunocytometry Systems, San S. A. Yonge et al.DOI: 10.4236/jbm.2019.71009103 Journal of Biosciences and Medicines cell absolute values and percentage per microlitre of sample.The system includes BD FACScount instrument, software, reagents, controls and a workstation.In brief, 50 μl of whole blood was mixed with monoclonal antibodies (MAbs) (5 µL of each T lymphocytes reagent tubes) and incubated at room temperature for 20 min with 20 μl of aCD4 and aCD8.Red blood cells were then lysed by adding 450 μl of fluorescence-activated cell sorter lysing solution (Becton Dickinson Immunocytometry Systems).The tubes were incubated at room temperature for 10 min, and then analyzed with the FACSCounts's Cell Quest software (Becton Dickinson Immunocytometry Systems) within six hours.By using quality control (Multicheck; Becton Dickinson Immunocytometry Systems), the accuracy of the technique was assessed every 6 months.

Table 1 .
15 ± 0.37 cells/litre.Mean absolute leukocytes cells in males was 4.89 ± 0.22 cells/litre and in females 5.40 ± 0.30 cells/litre.Mean absolute lymphocytes cells in males and females combined were 1.85 ± 0.29 cells/litre.The mean lymphocyte in males was 1.67 ± 0.20 cells/litre while in females mean was 2.02 ± 0.26 cells/litre.On Age distribution of immunocompetent adults in Coastal Kenya.

Table 3 .
Males and females with lower than normal and normal values of CD4 T cells, leukocytes, lymphocytes and body mass index (Controls).

Table 4 .
Haematological reference ranges (median percentile) derived from immunocompetent individuals from Coastal Kenya.