UCLA researchers in the Department of Medicine have developed lymphocyte stimulation assays to evaluate immune responses, supporting various clinical applications such as adjusting immunosuppressant drug levels and advancing COVID-19 vaccine development. The assay systems are reliable, cost-effective, and easy-to-perform, providing accurate assessments of immune response adequacy.
BACKGROUND: The immune response, mediated by a complex interaction between leukocytes and signaling molecules known as cytokines, is the body’s mechanism for defending against harmful or foreign antigens such as bacteria, viruses, cancer cells, and transplanted organs. The ability to accurately quantify antigen-specific immune responses holds significant clinical value. In solid organ transplantation, accurately assessing the level of immunosuppression in recipients is essential to prevent acute rejection from under-immunosuppression, as well as infections and malignancies resulting from over-immunosuppression. To date, there are still no reliable methods to assess a transplant recipient’s level of immunosuppression. Available methods for assessing immune function, such as the ImmuKnow assay, suffer from poor sensitivity, specificity, and limited clinical utility. More recently, the AlloSure Lung Test that measures the percent of donor-derived cell free DNA present in the plasma received FDA approval as a diagnostic test of acute rejection. Unfortunately, this test also has poor performance characteristics with a positive predictive value of 44%, negative predictive value of 84%, and a cost of over $2500 per test. The current assay developed by UCLA researchers has a cost of $20 with performance characteristics that are expected to exceed the AlloSure Lung Test.
Additionally, quantifying immune responses is crucial for efficient vaccine development, as it enables the assessment of an individual’s protection against pathogens such as COVID-19, evaluates immunity to novel variants, and aids in optimizing vaccine dosing. Despite the known importance of the cellular immune response in protection against infectious pathogens, available assays of cellular immunity are limited. Cellular responses to viral pathogens are most often measured using flow cytometry with intracellular staining or ELISPOT, both of which are expensive, labor-intensive and require specialized expertise, thus limiting their widespread application. Furthermore, these assays measure the frequency of responding cells, usually based on pre-determined cytokine panels that include interferon-gamma (IFNγ), interleukin (IL)-2, and tumor necrosis factor-alpha (TNFa), without regard for the magnitude of cytokine expression by each cell.
INNOVATION: UCLA researchers have developed a whole-blood T cell stimulation assay system (“Cytokine Response Assay” [CRA]) that provide several advantages over ELISPOT and flow cytometry with intracellular staining including: 1) simplicity, 2) improved sensitivity, 3) physiologic stimulation involving all whole blood components, 4) the ability to evaluate the concurrent expression of many cytokines quantitatively. The CRA relies on the stimulation of memory T Cells by proteins of interest (e.g. SARS-CoV-2, influenza) and measuring the cytokine response pattern. An evaluation of hundreds of cytokines have identified specific cytokine responses that can serve as optimal biomarkers of the cellular immune response in question. This novel assay has showed promising preliminary data in murine studies and clinical studies in lung transplant recipients, as well as influenza and COVID-19 vaccine recipients. It has the potential to improve clinical management after solid-organ transplant recipients and facilitate the development of novel vaccines.
POTENTIAL APPLICATIONS:
- Evaluating immune responses in various contexts, including reactions to transplanted donor tissues, infectious organisms such as COVID-19 and influenza, vaccinations, and tumor cells.
- Tailoring of immunosuppressive medications for solid organ transplant recipients and patients with autoimmune disease based on assay results.
- Tool for efficient screening and development of vaccines.
ADVANTAGES:
- The ability to quantitatively measure cellular immune response to any protein of interest.
- Physiologic T cell stimulation involving all whole blood components.
- The ability to evaluate the concurrent expression of many cytokines quantitatively.
- Simple, reliable, inexpensive, and easy-to-perform.
DEVELOPMENT-TO-DATE: Successful demonstration in murine tracheal transplant models, human lung transplant recipients, and individuals post influenza and SARS-CoV-2 mRNA vaccination.
KEYWORDS: Immunization, immune activation, immune response, lymphocyte stimulation, cytokines, ligand, cytokine receptor, interferon-gamma, antibody, organ transplantation, immunosuppression, acute rejection, chronic rejection, cellular response, vaccine, COVID-19, influenza, d2biomarkers.