Immune balance, the thymus and healthy aging
9:00 AM PST / 12:00 PM EST / 5:00 PM GMT / 6:00 PM CET
Recent studies show age-related immune decline, but the rate of decline varies between individuals.
Preserved thymic tissue and higher CD4 counts are markers of health, challenging older views that the thymus was no longer needed beyond young adulthood. New basic and clinical research has highlighted immune health biomarkers that are potentially actionable.
The strongest data comes from people living with HIV (PLWH) on effective therapy. Before antiretroviral treatment, CD4 cell counts and percentages were useful guides to complications. Once viral replication is suppressed, however, the absolute CD4 count loses much of its correlation with clinical events, whereas the CD4/CD8 ratio, which normalizes more slowly, retains its prognostic value. Recovery of the CD4/CD8 ratio is closely linked to thymic function, highlighting the role of immune renewal in immune competence.
In people without HIV, CD4 count and CD4/CD8 ratio can be combined to assess “Immune Resilience”, which correlates with infectious and non-infectious morbidity and certain cancers. In this webinar, Dr. Striker and Dr. Pacheco will discuss the clinical consequences of reduced thymic function and a low CD4/CD8 ratio, identify key knowledge gaps, and discuss how these biomarkers may improve risk stratification, inform clinical decisions, and guide interventions to preserve immune competence and promote healthy ageing.
Speakers
Robert Striker is a physician scientist. His PhD thesis was in microbiology. He has cared for patients with HIV and other immunocompromised patients for over twenty years at the University of Wisconsin. He completed the Medical Scientist Training Program at Washington University St Louis. He did a residency in San Francisco early in the HIV therapy era. He did an Infectious Diseases fellowship at Stanford. His clinical interests include chronic infections, particularly viral hepatitis, and HIV. Over the last 10 years, Dr Striker, and other clinical researchers have demonstrated that the degree of immune competence can be measured patients by comparing relatively simple immune parameters such as the CD4/CD8 ratio. How much this ratio deviates from a healthy, unstressed level of approximately 2 CD4 T cells in the peripheral blood for each CD8 T cell correlates with poor outcomes. These outcomes include not just infectious outcomes, but also the likelihood to develop specific cancers such as HPV related anogenital cancers, lymphomas, and lung cancer. While currently speculative, he is working to determine if this information could enhance clinical decision making. Theoretically some patients could be screened more or less frequently based on risk profiles including the immunes system.
Yolanda M. Pacheco is a translational biomedical researcher with over twenty years of experience in human immunology. After earning her degree in Pharmacy and a PhD in Health Sciences, she spent most of her scientific career at Virgen del Rocío University Hospital and the Institute of Biomedicine of Seville (IBiS, Spain).
During that period, her research has focused on understanding the mechanisms that regulate immune competence and T-cell homeostasis in both health and disease. Throughout her career, she has combined clinical and experimental approaches to investigate immune dysfunction in HIV and other emerging viral infections, including COVID-19, as well as vaccine responses and immunosenescence.
Her work has contributed to advancing our understanding of thymic function in immune reconstitution and the long-term preservation of T-cell populations throughout adulthood, including its relationship with CD4/CD8 ratio recovery in people living with HIV receiving antiretroviral therapy.
In 2026, she joined the Institute of Fat (IG-CSIC, Spain) to establish the Nutrition and Immune Homeostasis Research Group. Building on her previous research on T-cell homeostasis and immune recovery, her current work seeks to understand how nutritional and metabolic factors influence immune resilience and the maintenance of immune competence during ageing.