Diagnostic Flow Cytometry and the AIDS Pandemic

Cytomegalovirus serostatus among people with HIV, characterizing the prevalence, risk factors, and association with immune recovery

INTRODUCTION

Cytomegalovirus (CMV) infection is common among people with HIV (PWH), and may be associated with negative outcomes. We aimed to identify the seroprevalence of CMV between 01 January 1998 and 01 June 2022 among PWH accessing care at the Southern Alberta Clinic (SAC) and the associated risk factors. We also aimed to assess the impact of CMV seropositivity on CD4+ T-cells and CD4+/CD8+ ratio recovery among PWH who maintain HIV viral suppression.

METHODS

Poisson regression models with robust variance estimated crude and adjusted prevalence ratios and 95% confidence intervals to identify risk factors for CMV seronegativity. Among PWH maintaining viral suppression, trends in the median CD4+ T-cell count and CD4+/CD8+ ratio were visualized, and continuous time-to-event Cox proportional hazard models estimated hazards ratios (aHR) for CD4+ cell count recovery to ≥500 cells/mm3 and CD4+/CD8+ ratio of >1 at 10 years by CMV serostatus.

RESULTS

Among 3249 PWH, 2954 (91%) were CMV seropositive. CMV seronegativity was associated with younger ages, male sex, non-Hispanic white race and an education of ≥12 years. While CMV seronegativity did not affect CD4+ T-cell recovery following HIV viral suppression (aHR 1.15 [0.89-1.48]), it was associated with a greater likelihood of CD4+/CD8+ ratio normalization (aHR 2.38 [1.85-3.07]) at 10 years of follow-up.

CONCLUSIONS

CMV is a common coinfection among PWH. We found that CMV positivity among PWH maintaining HIV viral suppression, while not associated with CD4+ T-cell recovery, was associated with a reduced CD4+/CD8+ ratio recovery. This suggests an association with chronic CMV infection-mediated immune activation and inflammation among PWH.

Manipulating leukocyte populations to mimic immune disease states: a novel active approach to teaching flow cytometry to undergraduate immunology students

Flow cytometry detects and measures the physical and chemical characteristics of cells or particles. In medical laboratories, flow cytometers are used to quantify changes in cell populations associated with disease states, such as AIDS. While a powerful technique, it is challenging to teach the principles of flow cytometry to undergraduate students. One approach is to have students process and analyze a patient sample. However, this is not possible when the patient has an infectious disease. Here we report a two-stage approach to address this challenge. Magnetic beads were used to manipulate leukocytes cell populations in healthy blood to mimic the phenotype of eight immune disease conditions. The cells were then stained against cell surface markers for cell populations and analyzed by flow cytometry. The second stage focused on teaching flow cytometry over 2 wk. Week 1 involved a lecture, followed by a laboratory session where students learned how to stain a blood sample. In week 2, students worked in a computer pool to analyze the previously generated data and determine the immunological status of a control and patient sample. Using this approach, all students achieved 100% correct diagnosis of both control and patient samples. Student feedback via a questionnaire was overwhelmingly positive, and student perceived knowledge of flow cytometry increased after the session significantly. We effectively mimicked several disease states, eliminating the need to source patient samples, yet still teaching undergraduate students the principles of flow cytometry.

Predicción temporal de CD4+ en 80 pacientes con manejo antirretroviral a partir de valores de leucocitos

Objetivo: establecer una metodología predictiva de aplicación clínica de recuentos de CD4+ en rangos de interés clínico a partir del recuento absoluto de leucocitos.Metodología: a partir de los valores secuenciales de leucocitos y linfocitos CD4+ de 9 pacientes, se observaron patrones matemáticos que posteriormente fueronaplicados en un estudio ciego con 71 casos para confirmar su capacidad predictiva, midiendo porcentajes de especificidad y sensibilidad. Resultados: se determinaron cinco patrones matemáticos que predicen en el 99% de los casos los distintos recuentos de CD4+ a partir de recuentos de leucocitos con valores de especificidad y sensibilidad del 99%. Conclusiones: los patrones matemáticos encontrados entre recuento de leucocitos y CD4+ sugieren que este fenómeno prácticamente es determinista.

Prediction of CD4+ Cells Counts in HIV/AIDS Patients based on Sets and Probability Theories

BACKGROUND

Previous studies have developed methodologies for predicting the number of CD4+ cells from the total leukocyte and lymphocytes count based on mathematical methodologies, obtaining percentages of effectiveness prediction higher than 90% with a value of less than 5000 leukocytes.

OBJECTIVE

To improve the methodology probabilities prediction in 5000-9000 leukocytes ranges.

METHOD

from sets A, B, C and D defined in a previous study, and based on CD4+ prediction established on the total number of leukocytes and lymphocytes, induction was performed using data from 10 patients with HIV, redefining the sets A and C that describe the lymphocytes behavior relative to leukocytes. Subsequently, we evaluated with previous research prediction probabilities parameters from a sample of 100 patients, calculating the belonging probability to each sample and organized in predetermined ranges leukocytes, of each of the sets defined, their unions and intersections. Then the same procedure was performed with the new sets and the probability values obtained with the refined method were compared with respect to previously defined, by measures of sensitivity (SENS) and Negative Predictive Value (NPV) for each range.

RESULTS

probabilities with values greater than 0.83 were found in five of the nine ranges inside the new sets. The probability for the set A∪C increased from 0.06 to 0.18 which means increases between 0.06 and 0.09 for the intersection (A∪C) ∩ (B∪D), making evident the prediction improvement with new sets defined.

CONCLUSION

The results show that the new defined sets achieved a higher percentage of effectiveness to predict the CD4+ value cells, which represents a useful tool that can be proposed as a substitute for clinical values obtained by the flow cytometry.

Corrected Lymphocyte Percentages Reduce the Differences in Absolute CD4+ T Lymphocyte Counts between Dual-Platform and Single-Platform Flow Cytometric Approaches

Objective

To determine whether a corrected lymphocyte percentage could reduce bias in the absolute cluster of differentiation (CD)4+ T lymphocyte counts obtained via dual-platform (DP) vs standard single-platform (SP) flow cytometry.

Methods

The correction factor (CF) for the lymphocyte percentages was calculated at 6 laboratories. The absolute CD4+ T lymphocyte counts in 300 blood specimens infected with human immunodeficiency virus (HIV) were determined using the DP and SP methods.

Results

Applying the CFs revealed that 4 sites showed a decrease in the mean bias of absolute CD4+ T lymphocyte counts determined via DP vs standard SP (-109 vs -84 cells/μL, -80 vs -58 cells/μL, -52 vs -45 cells/μL, and -32 vs 1 cells/μL). However, 2 participating laboratories revealed an increase in the difference of the mean bias (-42 vs -49 cells/μL and -20 vs -69 cells/μL).

Conclusions

Use of the corrected lymphocyte percentage shows potential for decreasing the difference in CD4 counts between DP and the standard SP method.