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

Abstract

BackgroundCD4+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.ObjectiveTo quantify variation in absolute and relative lymphocyte subsets with age in healthy Malawians.MethodsLymphocyte subsets in peripheral blood of 539 healthy HIV-uninfected Malawians stratified by age were enumerated by flow cytometry.ResultsB 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.ConclusionAlthough 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.

Leukocyte counts and lymphocyte subsets in relation to pregnancy and HIV infection in Malawian women

“…However, our study provides additional information because it included comparisons between the four different groups, HIV‐infected and pregnant, HIV‐infected non‐pregnant, HIV‐uninfected pregnant and HIV‐uninfected non‐pregnant and it investigated the variation in more cell types than the other previous studies conducted in SSA 11, 12, 13, 25. It is worth mentioning that CD4 + and CD8 + T cells have been observed to be stable when presented as a percentage of the total lymphocyte counts than when they are presented as totals counts19, 23 and this is similar to what we and others have reported before for HIV‐uninfected children during childhood 26, 27. Therefore, percentage CD4 + and CD8 + T‐cell values may have better application than absolute counts for assessing immunodeficiency during pregnancy with an added advantage that they can be more easily and accurately performed on flow cytometers 28, 29…”

Reference Values of Lymphocyte Subsets in Healthy, HIV-Negative Children in Cameroon

“…In our study, the CD4 ϩ /CD8 ϩ ratio varied between 2.75 and 1.76, while in the Malawian study (10), the value varied from 2 to 1.5. The discrepancy could be due to the lower value of CD8 ϩ T cells observed in Cameroonian children compared to Malawian children.…”

“…We observed differences between studies conducted in developed countries but noted similarities to studies conducted in subSaharan Africa. The relative value of T lymphocytes in children 0 to 6 years old is higher in developed countries than in Cameroon and Malawi (10,18). The mean T-lymphocyte concentration for children 0 to 12 months old in developed countries is higher, while the values are similar in African children between 2 and 6 years old (24).…”

“…In the context of pediatric HIV infection, the principal immunologic change documented in large, multicentric, and longitudinal studies has been the CD4 T-lymphocyte count, which decreases rapidly in infected infants and children if compared to HIV-exposed (but uninfected) control subjects (1,14,19,22). Documented evidence shows that reference values are given for the major lymphocyte subsets, including B cells, NK cells, and T cells, including both T-helper and cytotoxic T-cell subsets (8,10,17,20). A smaller number of studies performed in the United States involve additional subsets, such as naive or effector T cells, with reports on activation markers being relatively rare (4,18).…”

Features of Stomatologic Status, Telomere Lengths and Phenotype of Immunocompetent Cells of Peripheral Blood in Children – Residents of Ukrainian Territories, Contaminated With Radionuclides

“…Some decrease of CD4 + -lymphocytes relative to normative values (33-41 %) was diagnosed in the examined patients from all studied groups. According to the literary data, decrease of CD4 + lymphocytes occurs at infectious, allergic and other diseases and may be used as a predictors of their course [29,30]. The amount of CD8 + (T-suppressors/cytotoxic) Т-lymphocytes in the examined children from groups No.…”