With the prevalence of infectious diseases, the rapid assessment of population-specific immune protection has become important for public health. A study published in Analytical Chemistry and led by Prof. TAN Xiaotian's team from the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences developed a new platform, known as Tip Optofluidic Immunoassay Interferon-Gamma Release Assay (TOI-IGRA), which could revolutionize how people monitor their immune health.

Evaluating T-cell responses is vital to understanding cellular immunity against intracellular threats such as Mycobacterium tuberculosis and SARS-CoV-2. Antibody measurements are common, but they do not provide the full picture of long-term protection that T-cells offers. The IGRA typically requires large volumes of venous blood and expensive laboratory infrastructure, restricting its application in community clinics or resource-limited settings.

The TOI-IGRA platform integrates the sensitive TOI biosensing system with a specialized micro-volume stimulation protocol. By optimizing the anticoagulation and dilution processes using a 0.9% NaCl environment, researchers demonstrated that fingertip blood preserved an immune cell composition almost identical to that of venous blood. The platform allows for the precise quantification of pathogen-specific T-cell responses using a mere 15-25 μL of fingertip blood.

Besides its diagnostic capabilities, the platform features a unique dual-modal testing approach that provides a holistic view of an individual's immunity. By combining T-cell functional analysis with quantitative antibody assays, the platform can simultaneously evaluate both cellular and humoral protection from the same micro-sample.

"This modular approach can be rapidly adapted for diverse pathogens by simply swapping the antigen peptide library, providing a new tool for community-based infectious disease management and large-scale public health surveillance," said Prof. TAN, the corresponding author of this study.