|Year : 2013 | Volume
| Issue : 2 | Page : 86-90
Reference values of CD4 T-lymphocytes in human immunodeficiency virus-exposed uninfected infants in Kano-Nigeria
Isyaku Umar Yarube1, Mudassar Ahmad2, Umar Muhammad Lawan3
1 Department of Physiology, Faculty of Medicine, Bayero University, Bayero University and Aminu Kano Teaching Hospital, Kano, Nigeria
2 Ahmadiyya Hospital, Kano, Nigeria
3 Department of Community Medicine, Faculty of Medicine, Bayero University, Bayero University and Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Web Publication||24-Dec-2013|
Isyaku Umar Yarube
P.O. Box 492, Kano
Source of Support: None, Conflict of Interest: None
Background: CD4 T-lymphocyte count has been known to be affected by several factors including ethnic group, region, age, sex and physiological conditions. Studies to evaluate CD4 count in vertically exposed, but human immunodeficiency virus (HIV) negative infants from this region have not been done previously. The aim of this study was to determine the reference values of CD4 counts, percentages and temporal profile in vertically exposed HIV negative infants residing in this environment.
Methodology: Blood samples were auto-analyzed using hematology machine made by Point Care Technologies, Inc. (Marlborough, MA, USA). All data were analyzed using statistical package for the social sciences 15.0 for Windows™. Median and 10 th and 90 th percentiles of CD4 cells were determined and analyzed using Mann-Whitney U test and Kendall's non-parametric correlations. P ≤0.05 values were considered to be significant.
Results: The values of CD4 counts in the infants studied were higher compared with adults. The values of CD4 count, %CD4 and their normal ranges were statistically the same for male and female sexes and within all age categories under 1 year. Although absolute CD4 cell count remained fairly constant from birth to the age of 1 year, %CD4 decreased gradually from birth toward the age of one.
Conclusions: For the first time in this environment, our study has reported absolute and percentage CD4 count, which were similar to those reported from other African studies. The results support the use of the same reference values for resident male and female infants for clinical decision making.
Keywords: CD4 count, infant, Nigeria, reference ranges
|How to cite this article:|
Yarube IU, Ahmad M, Lawan UM. Reference values of CD4 T-lymphocytes in human immunodeficiency virus-exposed uninfected infants in Kano-Nigeria. J Med Trop 2013;15:86-90
|How to cite this URL:|
Yarube IU, Ahmad M, Lawan UM. Reference values of CD4 T-lymphocytes in human immunodeficiency virus-exposed uninfected infants in Kano-Nigeria. J Med Trop [serial online] 2013 [cited 2019 Mar 25];15:86-90. Available from: http://www.jmedtropics.org/text.asp?2013/15/2/86/123577
| Introduction|| |
The CD4+ (T-helper) cells are T-lymphocytes that could be identified by the CD4 cluster of differentiation that coats their surface. They direct and coordinate cell-mediated physiologic immune response by stimulating the proliferation of B-cells and cytotoxic T-cells, attracting neutrophils and activating macrophages.  This makes it, apparently, the most important element of cellular response to infection. The CD4 antigen on the surface of the T-helper serves as the binding site for the human immunodeficiency virus (HIV). HIV infection leads to severe immune compromise due to depletion of CD4 cells.  For this reason, the CD4 count is used to determine when to commence or switch anti-retroviral therapy (ART) and when to administer or suspend prophylactic treatment of opportunistic infections.
Several studies have been conducted in Europe, Asia and elsewhere, to establish reference values of T-lymphocytes subsets. , Relatively few of such studies emanate from Africa. , In Nigeria, some studies have been conducted to establish CD4 counts in the adults. , There are even fewer such studies on neonates and infants.  The World Health Organization and centers for disease control reference values for CD4 cells count used in our clinics for management of HIV/acquired immunodeficiency syndrome is largely drawn from studies conducted on Caucasian populations. 
CD4 cells count has been known to be affected by several factors including ethnic group, age, sex, physiological condition, occupation, diet, nutritional status, medication and season. ,, Furthermore, Mwinga et al.  reported difference in hematological parameters in HIV-exposed, but uninfected infants when compared with HIV-unexposed infants. However, CD4 and CD8 values of HIV-exposed infants could be used as reference values for normal infants. , In this study, the values of CD4 cell absolute count, percentage and temporal profile of healthy, HIV negative infants born to HIV positive mothers in an African population were evaluated.
| Methodology|| |
Ahmadiyya hospital is located in the heart of Kano metropolis, North Western Nigeria. ART clinic for HIV infected individuals was started in June 2006, with support from international non-governmental organizations. Since inception, 1546 adult and 316 pediatric HIV patients had been enrolled. Currently, 705 adult (647 receiving anti-retroviral drugs (ARVs)) and 113 pediatric (30 receiving ARVs) patients, including 16 pregnant women for prevention of mother-to-child transmission (PMTCT) of HIV infection, are accessing care and treatment at this facility. On an average, about 633 visits were recorded per month.
The study was conducted from June 2008 to July 2009. All pregnant women that attended the clinic were offered HIV counseling and testing using the opt-out technique. The HIV positive mothers were confirmed seropositive using Determine™ and Unigold™ test kits by the parallel algorithm. They received a single dose Nevirapine (NVP) at the onset of labor for PMTCT. The infants received a single dose NVP within 72 h of birth and AZT with zidovudine (ZDV) within the first 6 weeks of life. All the babies born to these mothers were screened for HIV infection using antibody-based and polymerase chain reaction tests. The infants' weight and CD 4 count were determined.
The study design was descriptive, cross-sectional and the study population consisted of babies of HIV positive mothers receiving care at the Ahmadiyya ART clinic. All the babies born to these women within the study period were eligible for the study. Ethical clearance for the study was obtained from the institutional review board of Ahmadiyya Hospital, Kano. Informed consent was obtained from the parents or guardians of the subjects before the commencement of data collection. Patients' anonymity was preserved. The work conforms to the provisions of the Declaration of Helsinki in 1995 (as revised in Tokyo 2004).
All HIV positive babies were excluded from the study. Similarly, babies with concurrent illness, history of medication (except multivitamins, co-trimoxazole and AZT), axillary temperature > 38.0°C and malnutrition (weight for height of < 70%) were excluded.
A total volume of 5 ml of venous blood was collected from each of the eligible babies at the hospital laboratory between the hours of 8:30-12:00, for the purpose of estimating CD4 count and %CD4. The blood samples were auto-analyzed using hematology machine made by PointCare Technologies, Inc. (Marlborough, MA, USA) according to manufacturer's protocols. The %CD4 values were however available for only 62 infants (33 boys and 29 females) due to technical challenges, which constituted a limitation of this study.
The data were collected and analyzed using statistical package for the social sciences 15.0 for Windows™ (IBM Corporation, U.S.A.). Median and 10 th and 90 th percentiles were determined for the CD4 values of the infants within each age group. The effect of sex was evaluated using Mann-Whitney U test and Kendall's non-parametric correlations were used to determine variation with age. P values were considered as significant at ≤0.05.
| Results|| |
A total of 173 babies were delivered to the mothers within the study period, but only 1 (0.006%) turned out HIV positive. However, consent for the study was obtained on behalf of only 130 uninfected babies and hence only these were enrolled for the study. The response rate was thus 75.6%.
The median age of the uninfected infants was 121 days with a range of 360 days. 41.5% of them were not more than 3 months of age as shown in [Table 1].
All the 130 CD4 test results of the uninfected infants were analysed. The absolute counts, percentages as well as the 10 th and 90 th percentiles of CD4 cells were determined for both sexes combined and separately, and presented in [Table 2].
|Table 2: Reference ranges of absolute CD4 cells count and percentage CD4 cells of HIV-exposed uninfected infants |
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The median CD4 (Range) of the male and female babies combined was 2019 with a range of 4500 cells/ml; while it was 2019 with arrange of 4500 cells/ml, and 2011 with a range of 3132 cells/ml, in the male and female subjects respectively. The CD4 values were similar in the two sexes (Mann-Whitney U = 4126.5, P > 0.05). Similarly, the CD4 percentage between the two sexes were similar (Mann-Whitney U = 1010.5, P > 0.05).
We also computed the median and the 10 th and 90 th percentiles CD4 counts and %CD4 of the infants based on age groups and by sex [Table 3]. There was no statistically significant difference between the CD 4 counts and percentages of the male and female groups in all the age categories.
|Table 3: Reference ranges of CD4 cells count of HIV-exposed uninfected infants by age and sex |
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The variation of CD4 cells count with age was also examined [Figure 1]. The plot shows a very weak positive correlation between the CD4 counts and the ages of the infants, although the relationship was statistically not significant (Kendall's tau b correlation coefficient = 0.02, P = 0.72). In the same vein, the percentage CD4 of the infants were plotted against their ages and presented in [Figure 2]. The plot shows an imperfect negative correlation between the respondents ages and the percentage CD4 cells and the relationship was statistically significant (Kendall's tau b correlation coefficient = −0.28, P = 0.001).
|Figure 1: Variations of the absolute CD4 Counts of the human immunodeficiency virus-exposed uninfected infants with age|
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|Figure 2: Variations of the percentage CD4 of the human immunodeficiency virus-exposed uninfected infants with age|
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| Discussion|| |
The median CD4 count of the infants in our study was 2019 cells/mL, with a mean age of 121 days (about 4 months). This is less than the values found in Asian  and European children  of that age bracket. Our result corroborates the reports of Idigbe et al.  of their study conducted on Nigerian children. In that study, most of children below the age of 1 year had CD4 counts above 2000, though the flow cytometer (FACSCount™, Becton, Dickinson and Company, U. S. A.) used could not determine CD4 count above this value. The median CD4 count of 2019 in males and 2011 in females were statistically the same when compared to each other or with that of both sexes, indicating no gender difference at this age. This finding agrees with other reports in African children, , but disagrees with other findings in European and Asian Children. ,
Our study has reported absolute CD4 counts and percentages of neonates less than 1 month old to be 2217 cell/mL and 64.4% for males, and 2132 cells/mL and 55.6% for females, respectively [Table 3]. CD4 count for males were the lowest in the 181-270 days and highest in the 0-28 days age categories. For females, CD4 count were the lowest in the 91-181 days and highest in the 271-365 days age categories. However, there was no statistically significant difference between the CD4 values within the age groups for both sexes. This result does not agree with the findings of Idigbe et al.  who reported a higher CD4 count value in females. This could be explained by the inclusion of children above 5 years of age in their study.
A relatively wide range of normal CD4 count from 1049 to 2991 cells/mL for both sexes at a mean age of 121 days has been revealed by our study [Table 3]. This is similar to the findings in previous studies among Nigerian adults  and children,  as well as Thai children.  The wide range of CD4 value makes clinical decision making difficult without the CD4 percentage. Percent CD4 of 34.4% at the mean age of 118 days in our study is in support of other findings in African infants.  Commencing ART at CD4 below 25% in children seems appropriate since this represents a decline of about one-third from average, which may indicate severe immunocompromise.
Absolute CD4 count remains fairly constant within the 1 st year of life at about 2000 cells/mL in our study [Figure 1]. However, %CD4 showed a steady decline from its highest value of 60% at birth (first 2 days of life) to about 27% towards the age of 1 year [Figure 2]. Similarly, %CD4 was consistently highest in the 0-28 days and lowest in the 271-365 days age categories in both males and females [Table 3].This makes the CD4 percentage a better index of CD4 temporal profile. Idigbe et al.  reported a similar trend with the highest value of 35.9% in neonates and the lowest value of 26.6% in infants.
Our study has, for the first time in this environment, reported absolute and percentage CD4 count reference values as well as CD4 dynamics, which was similar to reports from other African studies. There are no gender differences in CD4 counts and percentages in infants under 1 year, which is in support of applying the same threshold values for commencement of ART irrespective of sex in this category of people.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]