Population studies showed that there are differences in T-lymphocytes subpopulation of normal children in different regions, and reference values in an area might be different from another. This study compared the values in our population with CDC and WHO reference values. Blood samples from 279 healthy, HIV-negative children 12 years of age were analysed for complete blood count, CD3+, CD4+, CD8+ counts and percentages. Except for CD8%, mean values for all parameters measured significantly decreased with age. CD4+ counts were higher in females than males, . Using the WHO criteria, 15.9% of subjects had low total lymphocyte count and 20.6% had low CD4 count. Children 3 years had median CD4% lower than WHO normal values. Our median CD4+ counts correlated with CDC values. Values used by WHO in infants are higher than ours. We suggest that our children be assessed using CDC reference values which correlate with ours. 1. Introduction The mature T-lymphocytes are defined by the presence of CD3, and either CD4+ or CD8+ unit antigens [1]. The CD4+ antigen-bearing T-lymphocyte subset also known as the T-helper cells has become popular since the advent of the Human Immunodeficiency Virus (HIV) infection. These T-lymphocytes are the primary targets of the HIV infection because the CD4+ antigen is the primary binding site of the HIV [2–4]. CD4+T cells serve as both essential regulators and effectors of the immune response; infection with HIV induces a progressive loss of these cells [5]. Profound decline of these cells underlies the immunodeficiency that results in Acquired Immunodeficiency Syndrome (AIDS) [2] The CD4+ T-cell count is the standard for assessing the immunologic progression of the disease, determination of need to commence antiretroviral (ARV) treatment, chemoprophylaxis for opportunistic infections, and for monitoring or modifying antiretroviral treatment [6, 7]. An adult individual has about 3000 lymphocytes per mm [3] in the peripheral blood with 70%–80% being T-lymphocytes and 65% of these T-lymphocytes bear CD4+ antigens [8, 9]. In children, the number of circulating T-cells increases from mid-gestation until the infant is about 6 months. This peak is followed by a gradual decline throughout childhood until adult levels are reached by late childhood [10]. As a result of the age-related changes in the absolute lymphocyte numbers and thus CD4+ count, the Centers for Disease Control and Prevention (CDC) in classifying children into immune categories using CD4+, produced a system based on specific age groups [11]. The World Health Organization
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