Evidence-Based Supplement & Herb Guides

Interleukin-5 (IL-5) Test: Eosinophilic Inflammation, Allergy, Asthma, and Meaning

Learn what an IL-5 test measures, how it relates to eosinophils, asthma, allergy, and eosinophilic disease, and why high or low results require clinical context.

An interleukin-5 (IL-5) test measures a cytokine that promotes eosinophil development, survival, activation, and movement from bone marrow into blood and tissues. IL-5 is...

Interleukin-6 (IL-6) Test: High Levels, Inflammation, Cytokine Activity, and Immune Response

Understand what an IL-6 test measures, why levels rise in infection and inflammation, how timing and treatment affect results, and which follow-up tests add clinical meaning.

An interleukin-6 (IL-6) test measures a rapidly changing cytokine involved in infection defense, inflammation, antibody responses, blood-cell production, metabolism, and tissue repair. IL-6 can...

Interleukin-8 (IL-8) Test: Neutrophil Inflammation, Infection Response, and Meaning

Understand what an IL-8 or CXCL8 test measures, how it directs neutrophil inflammation, why high levels are nonspecific, and which follow-up tests clarify infection and tissue injury.

An interleukin-8 (IL-8) test measures a chemokine—also named CXCL8—that directs neutrophils toward infection, tissue injury, and other inflammatory signals. IL-8 can rise quickly when...

Interleukin-10 (IL-10) Test: Immune Regulation, Inflammation Control, and Meaning

Understand what an IL-10 test measures, why interleukin-10 may be high or undetectable, and how this regulatory cytokine is interpreted in inflammation, infection, autoimmunity, and cancer.

An interleukin-10 test measures a cytokine that helps prevent an immune response from causing unnecessary damage. Interleukin-10, abbreviated IL-10, is often described as anti-inflammatory,...

Interleukin-12 (IL-12) Test: Immune Activation, T-Cell Response, and Meaning

Learn what an IL-12 test measures, how IL-12p70 differs from p40 and IL-23, and what high, low, or undetectable results may mean for T-cell and infection responses.

An interleukin-12 test measures a cytokine that connects early innate immune sensing with a strong cellular immune response. Interleukin-12, or IL-12, is produced mainly...

Interleukin-17 (IL-17) Test: Autoimmune Inflammation, Th17 Response, and Meaning

Learn what an IL-17 test measures, how IL-17A and Th17 cells affect autoimmune inflammation and Candida defense, and what high, low, or undetectable results may mean.

An interleukin-17 test measures a cytokine involved in barrier defense, neutrophil recruitment, and several immune-mediated inflammatory diseases. The name “IL-17” usually refers to IL-17A,...

Interleukin-18 (IL-18) Test: Inflammation, Macrophage Activation, and Hyperinflammation

Understand total and free IL-18 testing, why interleukin-18 may be extremely high in Still disease, MAS, or autoinflammation, and how results guide urgent follow-up.

An interleukin-18 test measures an inflammasome-related cytokine that can become markedly elevated in several hyperinflammatory disorders. Interleukin-18, abbreviated IL-18, is made as an inactive...

Interleukin-23 (IL-23) Test: Autoimmune Inflammation, Th17 Pathway, and Meaning

Learn what an IL-23 test measures, how the Th17 pathway affects autoimmune inflammation, why high or low results are limited, and how related diseases are evaluated.

An interleukin-23 (IL-23) test measures a cytokine involved in type 17 immunity, a defense system that helps protect skin and mucosal surfaces from selected...

Lymphocyte Proliferation Test: T-Cell Function, Mitogen Response, and Immune Deficiency

Learn how lymphocyte proliferation tests measure T-cell division, why mitogen and antigen responses differ, what low results mean, and how specimen handling affects accuracy.

A lymphocyte proliferation test evaluates whether living lymphocytes—especially T cells—can activate and divide after stimulation in the laboratory. It is a functional test, not...

Lymphocyte Subset Panel: T Cells, B Cells, NK Cells, CD4/CD8 Ratio, and Immune Function

Understand how a lymphocyte subset panel measures T, B, and NK cells, why absolute counts and percentages differ, and how CD4/CD8 patterns guide immune evaluation.

A lymphocyte subset panel uses flow cytometry to count major immune-cell populations in blood, usually CD3 T cells, CD4 helper T cells, CD8 cytotoxic...

Macrophage Activation Syndrome Blood Test Panel: Ferritin, IL-18, Cytokines, and Hyperinflammation

Learn how a macrophage activation syndrome blood test panel uses ferritin, blood counts, fibrinogen, liver tests, IL-18, and cytokine markers to detect dangerous hyperinflammation.

A macrophage activation syndrome blood test panel is not one single laboratory test. It is a coordinated set of urgent studies used when clinicians...

Natural Killer Cell Count Test: NK Cells, Immune Function, and Viral Defense

Understand what a natural killer cell count measures, why CD16 and CD56 identify NK cells, and how low or high results relate to viral defense, immune deficiency, treatment, and function.

A natural killer cell count test measures the number and percentage of circulating NK cells, usually by flow cytometry. Most laboratories identify NK cells...

Natural Killer Cell Function Test: NK Cell Activity, Immune Defense, and Meaning

Learn how natural killer cell function tests measure cytotoxicity, CD107a degranulation, perforin, and immune activity, and why specimen handling and clinical context determine the meaning.

A natural killer cell function test evaluates how well NK cells respond to stimulation or damage target cells in the laboratory. Depending on the...

Neutrophil Oxidative Burst Test: Chronic Granulomatous Disease Screening and Neutrophil Function

Learn how the neutrophil oxidative burst DHR test screens for chronic granulomatous disease, identifies carrier patterns, measures residual NADPH oxidase activity, and avoids false interpretation.

A neutrophil oxidative burst test measures whether neutrophils can generate reactive oxygen species after stimulation. The most widely used method is the dihydrorhodamine 123,...

Regulatory T-Cell Test: Tregs, Immune Tolerance, Autoimmunity, and Meaning

Understand how regulatory T-cell testing measures CD4 CD25-high CD127-low FOXP3-positive cells, what low or high Tregs may mean, and why IPEX requires genetic confirmation.

A regulatory T-cell test uses flow cytometry to estimate the number or percentage of circulating Tregs, most often within the CD4 T-cell population. Clinical...

Soluble IL-2 Receptor Test: Immune Activation, Inflammation, Sarcoidosis, and Lymphoma Risk

Understand what a soluble IL-2 receptor or sCD25 test measures, why levels rise in HLH, sarcoidosis, lymphoma, infection, and inflammation, and why the result is not disease-specific.

A soluble IL-2 receptor test measures circulating soluble interleukin-2 receptor alpha, also called sIL-2R alpha, sCD25, or soluble CD25. Activated lymphocytes and some other...

T-Cell Count Test: CD3 Cells, Immune Function, and Lymphocyte Subsets

Understand how a CD3 T-cell count measures circulating T lymphocytes, why absolute counts and percentages differ, and how low or high results guide immune-function and subset evaluation.

A T-cell count test measures circulating lymphocytes that express CD3, the marker found on most mature T cells. Flow cytometry usually reports both the...

Transforming Growth Factor-Beta (TGF-Beta) Test: Immune Regulation, Fibrosis, and Meaning

Understand what a TGF-beta 1 blood test measures, why platelets and latent protein affect results, and why high levels cannot diagnose fibrosis, immune dysregulation, or cancer alone.

A transforming growth factor-beta test measures a TGF-beta protein in blood, most often TGF-beta 1. TGF-beta regulates immune tolerance, wound repair, extracellular-matrix production, blood-vessel...

Tumor Necrosis Factor-Alpha (TNF-Alpha) Test: High Levels, Inflammation, and Cytokine Activity

Understand what a TNF-alpha blood test measures, why levels may be high or normal, major limitations, anti-TNF treatment differences, and appropriate follow-up.

A tumor necrosis factor-alpha test measures TNF-alpha, a powerful immune signaling protein involved in inflammation, infection defense, blood-vessel activation, fever, tissue repair, and cell...

Vascular Endothelial Growth Factor (VEGF) Test: Inflammation, Angiogenesis, and Blood Vessel Growth

Learn what a VEGF blood test measures, why serum and plasma differ, how platelets affect results, its role in POEMS syndrome, and what high levels can mean.

A vascular endothelial growth factor test measures a protein signal involved in blood-vessel growth, vessel permeability, tissue repair, and responses to low oxygen. Most...