From the Guidelines
Lymphocyte subset count by flow cytometry is a crucial diagnostic tool in Human Immunodeficiency Virus (HIV) infection, as it provides essential information for monitoring disease progression and treatment effectiveness. This test is vital for assessing immune function, guiding clinical decisions, and evaluating the risk of opportunistic infections. The standard protocol involves measuring absolute CD4+ T-cell counts and percentages, along with CD8+ T-cells and CD4:CD8 ratios, using single-platform technology with CD45 gating, as recommended by the Centers for Disease Control and Prevention (CDC) 1.
Key Considerations
- The CDC guidelines emphasize the importance of accurate and reliable measures of CD4+ T lymphocytes for managing HIV-infected individuals 1.
- Flow cytometry is the preferred method for lymphocyte subset counting due to its accuracy and reproducibility in measuring specific immune cell subsets 1.
- CD4 testing is recommended at diagnosis and every 3-6 months during stable disease, with more frequent monitoring if therapy is initiated or changed 1.
- CD4 counts below 200 cells/μL indicate severe immunosuppression and increased risk for opportunistic infections, highlighting the need for regular monitoring and timely intervention.
Clinical Implications
- Lymphocyte subset count by flow cytometry guides critical clinical decisions, including when to start antiretroviral therapy (ART), initiate opportunistic infection prophylaxis, and assess response to treatment.
- The test helps evaluate disease progression and treatment effectiveness, allowing for adjustments to the treatment plan as needed.
- Regular monitoring of CD4+ T-cell counts and percentages enables healthcare providers to identify potential issues early on and take proactive measures to prevent complications and improve patient outcomes.
From the Research
Lymphocyte Subset Count by Flow Cytometry in HIV
- Lymphocyte subset count by flow cytometry is a valuable tool in monitoring HIV infection and AIDS, as it provides accurate and cost-effective measurements of lymphocyte subsets 2.
- The technique has been used to enumerate five lymphocyte subsets, including CD4 lymphocytes, which are crucial in monitoring disease progression and prognosis in HIV-infected patients 3.
- Flow cytometry has facilitated the understanding of the biology of HIV and the mechanisms of the immune system's response to the virus, allowing for the monitoring of antiretroviral therapy efficacy 4.
Reference Values and Methodologies
- Reference values of lymphocyte subsets have been determined in HIV seronegative and seropositive adults, with significant sex and geographical differences observed 5.
- Different flow cytometric methods, such as MultiSET and SimulSET, have been compared and shown to have high correlation coefficients for CD3+, CD4+, and CD8+ T-lymphocyte counts and percentages 5.
- A new volumetric method for lymphocyte subset enumeration has been evaluated and shown to produce metrologically traceable results, with a high degree of correlation with established bead-based methodologies 6.
Clinical Applications
- Lymphocyte subset enumeration by flow cytometry is important for therapeutic monitoring of HIV infection and other conditions, with accurate and reliable results being crucial for clinical decision-making 2, 3, 6.
- The technique has been used to monitor disease progression, evaluate therapy, and understand the immune system's response to HIV, making it a valuable tool in the management of HIV-infected patients 2, 3, 4.