Cytokine Analysis: A Snapshot of Immune Response

What are cytokines, and what can they tell us?

Cytokines represent a broad category of signaling molecules that are both secreted by and act upon immune cells, and are commonly measured in serum as an indicator of systemic immune response. These molecules are highly valued as minimally invasive markers of systemic immune status, capturing elements of overall health, disease progression, and treatment efficacy in experimental models. Cytokine signaling helps maintain tissue homeostasis and immune function in non-diseased states. Cytokine signaling is altered both in response to disease, infection, and injury, and can also be a direct contributor to disease development (cytokine release syndrome) when normal signaling is inhibited or enhanced. Understanding which cytokines are present as well as how their expression changes over time. Analysis of cytokine profiles in response to disease and subsequent intervention provides highly valuable insight into systemic immune response. 

Major Classes of Cytokines:

• Interferons: Involved in innate immune response – released by infected cells to initiate immune response to viral infection
• Interleukins: Mediate communication between immune and non-immune cells
• Chemokines: Direct immune cell recruitment and migration
• Tumor Necrosis Factors: Involved in acute inflammatory response, immune cell recruitment
• Growth Factors: Tissue repair  

How do we measure cytokines?

Cytokines are most informative when measured as a profile of multiple signaling molecules to capture the full context of the immune signaling milieu. Cytokines are both pleiotropic (having multiple downstream effects) and redundant (multiple cytokines can enact the same downstream effect). Interpretation of the roles being played by cytokines being expressed at a given timepoint is dependent on understanding of the signaling profile as a whole. 

We utilize Luminex technology to allow for the simultaneous measurement of >30 cytokines in the same small-volume sample. Multiplexing technology has significant animal welfare and research advantages when compared to traditional methods (eg. ELISA), as it allows for reduced animal handling, reduced blood draw volume, and increased research efficiency.

We use a commercial cytokine assays that have undergone confirmatory in-house assay qualification to ensure the assay performs well in our laboratory. This qualification includes assessment of precision (agreement between replicate measurements), spike recovery (the ability to accurately measure a known concentration of analyte in the test matrix), linearity (the ability of the method to elicit results that are directly proportional to the analyte concentration), and sensitivity.