Sex and Urbanicity Contribute to Variation in Lymphocyte Distribution across Ugandan Populations.

Management of patient care and interpretation of research data require evaluation of laboratory results in the context of reference data from populations with known health status to adequately diagnose disease or make a physiological assessment. Few studies have addressed the diversity of lymphocyte subsets in rural and urban Ugandan populations. Here, 663 healthy blood bank donors from semi-urban centers of Kampala consented to participate in a study to define lymphocyte reference ranges. Whole blood immunophenotyping was performed to determine the frequency and absolute counts of T, B, and NK cells using clinical flow cytometry. Results from blood bank donors were compared to a rural cohort from the district of Kayunga and more urban clinical trial participants from the capital city, Kampala. Relationships between hematological and lymphocyte parameters were also explored. In the semi-urban blood donors, females were significantly different from males in all parameters except the frequency of CD8 T and B cells. Females had higher absolute counts of CD4 T, CD8 T and B cells, whereas males had higher NK cell counts. NK cell frequency and counts were significantly higher in semi-urban blood donors, regardless of sex, compared to more urban study participants. CD8 T cell frequency and counts were significantly higher in the blood donors compared to the rural participants, irrespective of sex. Interestingly, basophil counts were positively associated with overall T cell counts. These findings suggest that both sex and level of cohort urbanicity may influence lymphocyte subset distributions in Ugandans.

Quality monitoring of HIV-1-infected and uninfected peripheral blood mononuclear cell samples in a resource-limited setting.

Human immunodeficiency virus type 1 (HIV-1) vaccine and natural history studies are critically dependent on the ability to isolate, cryopreserve, and thaw peripheral blood mononuclear cell (PBMC) samples with a high level of quality and reproducibility. Here we characterize the yield, viability, phenotype, and function of PBMC from HIV-1-infected and uninfected Ugandans and describe measures to ascertain reproducibility and sample quality at the sites that perform cryopreservation. We have developed a comprehensive internal quality control program to monitor processing, including components of method validation. Quality indicators for real-time performance assessment included the time from venipuncture to cryopreservation, time for PBMC processing, yield of PBMC from whole blood, and viability of the PBMC before cryopreservation. Immune phenotype analysis indicated lowered B-cell frequencies following processing and cryopreservation for both HIV-1-infected and uninfected subjects (P < 0.007), but all other major lymphocyte subsets were unchanged. Long-term cryopreservation did not impact function, as unstimulated specimens exhibited low background and all specimens responded to staphylococcal enterotoxin B (SEB) by gamma interferon and interleukin-2 production, as measured by intracellular cytokine staining. Samples stored for more than 3 years did not decay with regard to yield or viability, regardless of HIV-1 infection status. These results demonstrate that it is possible to achieve the high level of quality necessary for vaccine trials and natural history studies in a resource-limited setting and provide strategies for laboratories to monitor PBMC processing performance.

Reference intervals in healthy adult Ugandan blood donors and their impact on conducting international vaccine trials.

BACKGROUND: Clinical trials are increasingly being conducted internationally. In order to ensure enrollment of healthy participants and proper safety evaluation of vaccine candidates, established reference intervals for clinical tests are required in the target population. METHODOLOGY/PRINCIPAL FINDINGS: We report a reference range study conducted in Ugandan adult blood bank donors establishing reference intervals for hematology and clinical chemistry parameters. Several differences were observed when compared to previously established values from the United States, most notably in neutrophils and eosinophils. CONCLUSIONS/SIGNIFICANCE: In a recently conducted vaccine trial in Uganda, 31 percent (n = 69) of volunteers screened (n = 223) were excluded due to hematologic abnormalities. If local reference ranges had been employed, 83% of those screened out due to these abnormalities could have been included in the study, drastically reducing workload and cost associated with the screening process. In addition, toxicity tables used in vaccine and drug trial safety evaluations may need adjustment as some clinical reference ranges determined in this study overlap with grade 1 and grade 2 adverse events.