CD4+ T lymphocyte reference values of immunocompetent subjects in an African university

Region-specific laboratory reference intervals are important: A systematic review of the data from Africa

Region-specific laboratory reference intervals (RIs) are important for clinical trials and these data are often sparse in priority areas for research, including Africa. We reviewed data on RIs from Africa to identify gaps in the literature with a systematic review of PubMed for RI studies from Africa published ≥2010. Search focus included clinical analytic chemistry, hematology, immunological parameters and RIs. Data from adults, adolescents, children, pregnant women, and the elderly were included. We excluded manuscripts reporting data from persons with conditions that might preclude clinical trial participation in studies enrolling healthy volunteers. Of 179 identified manuscripts, 80 were included in this review, covering 20 countries with the largest number of studies in Ethiopia (n = 23, 29%). Most studies considered healthy, nonpregnant adults (n = 55, 69%). Nine (11%) studies included pregnant women, 13 (16%) included adolescents and 22 (28%) included children. Recruitment, screening, enrollment procedures and definition of age strata varied across studies. The most common type of RIs reported were hematology (66, 83%); 14 studies (18%) included flow cytometry and/or T cell counts. Other common tests or panels included liver function assays (32, 40%), renal function assays (30, 38%), lipid chemistries (17, 21%) and serum electrolytes (17, 21%). The number of parameters characterized ranged from only one (three studies characterized either CD4+ counts, D-dimer, or hemoglobin), to as many as 40. Statistical methods for calculating RIs varied. 56 (70%) studies compared their results to international RI databases. Though most presented their data side-by-side with international data with little accompanying analysis, nearly all reported deviation from comparator RI data, sometimes with half or more of otherwise healthy participants having an "out of range" result. We found there is limited local RI data available in sub-Saharan Africa. Studies to fill this gap are warranted, including efforts to standardize statistical methods to derive RIs, methods to compare with other RIs, and improve representative participant selection.

A Critical Review on the Standardization and Quality Assessment of Nonfunctional Laboratory Tests Frequently Used to Identify Inborn Errors of Immunity

Inborn errors of immunity (IEI), which were previously termed primary immunodeficiency diseases, represent a large and growing heterogeneous group of diseases that are mostly monogenic. In addition to increased susceptibility to infections, other clinical phenotypes have recently been associated with IEI, such as autoimmune disorders, severe allergies, autoinflammatory disorders, benign lymphoproliferative diseases, and malignant manifestations. The IUIS 2019 classification comprises 430 distinct defects that, although rare individually, represent a group affecting a significant number of patients, with an overall prevalence of 1:1,200-2,000 in the general population. Early IEI diagnosis is critical for appropriate therapy and genetic counseling, however, this process is deeply dependent on accurate laboratory tests. Despite the striking importance of laboratory data for clinical immunologists, several IEI-relevant immunoassays still lack standardization, including standardized protocols, reference materials, and external quality assessment programs. Moreover, well-established reference values mostly remain to be determined, especially for early ages, when the most severe conditions manifest and diagnosis is critical for patient survival. In this article, we intend to approach the issue of standardization and quality control of the nonfunctional diagnostic tests used for IEI, focusing on those frequently utilized in clinical practice. Herein, we will focus on discussing the issues of nonfunctional immunoassays (flow cytometry, enzyme-linked immunosorbent assays, and turbidimetry/nephelometry, among others), as defined by the pure quantification of proteins or cell subsets without cell activation or cell culture-based methods.

CD4- and CD3-T lymphocyte reference values of immunocompetent urban and rural subjects in an African nation

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 combination antiretroviral therapy (cART). The aim of the present study was to determine and compare the reference values of CD4 and CD3 T cells in urban and rural Nigerians who were human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) negative. After ethical clearance and informed consent, 1123 subjects who met the inclusion criteria [mean age = 24.4 (± 11.2) years] were recruited in this study. Blood samples were analysed using the BD FACScount cytometer according to the manufacturer's instructions. Of the overall 1123 subjects, reference means of CD4, CD3 and CD4/CD3 ratio were 1030 ± 367, 1757 ± 609 cells/μl and 0.59 ± 0.08, respectively. Five hundred and fifty-one (49.1%) were an urban population with the mean CD4, CD3 and CD4/CD3 T cell ratio of 1032 ± 369, 1761 ± 612 cells/μl and 0.59 (±0.08), respectively. The remaining 572 (50.9%) were of a rural population with the mean CD4, CD3 and CD4/CD3 T cell ratio of 1028 ± 459, 1753 ± 958 cells/μl and 0.59 ± 0.13, respectively. Subjects with higher CD4 and CD3 T cells were more likely to be female than male (P < 0.05). There was no significant difference between the T cell values of the two populations (P > 0.05). Our findings provide new insight in the CD4 and CD3 T cell reference values of Nigerians.