Natural Killer Cell Function Test: NK Cell Activity, Immune Defense, and 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
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
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
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
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
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
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
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...
AH50 Complement Test: Alternative Pathway Activity, Low Levels, and Immune Function
The AH50 complement test measures whether the alternative complement pathway can complete its immune-defense cascade. This pathway is part of the innate immune system,...
C1 Esterase Inhibitor Antigen Test: Hereditary Angioedema, Low Levels, and Diagnosis
The C1 esterase inhibitor antigen test measures how much C1 inhibitor protein is present in the blood. It is a central test for hereditary...
C1 Esterase Inhibitor Function Test: Hereditary Angioedema, Functional Deficiency, and Diagnosis
The C1 esterase inhibitor function test checks whether C1 inhibitor protein can control the enzyme systems that generate bradykinin. It is the most direct...
CH50 Complement Test: Total Complement Activity, High and Low Levels, and Immune Function
The CH50 complement test measures whether the classical and terminal complement pathways can work together to destroy a target. It is a functional screening...
Common Variable Immunodeficiency Test Panel: IgG, IgA, IgM, Vaccine Response, and Diagnosis
A common variable immunodeficiency test panel evaluates whether the body makes enough antibodies and whether those antibodies respond normally to vaccines. The core findings...
Complement and Immunoglobulin Blood Test Panel: C3, C4, CH50, IgG, IgA, IgM, and Immune Function
A complement and immunoglobulin blood test panel examines two different parts of immune defense. C3, C4, and CH50 assess complement proteins that tag microbes,...
Complement C1q Test: Low Levels, Immune Complex Disease, and Lupus Nephritis Risk
The complement C1q test measures the amount—or, in some laboratories, the function—of C1q, the recognition protein that starts the classical complement pathway. C1q helps...
Complement C3 Test: High, Low, Normal Range, Autoimmune Disease, and Immune Meaning
A complement C3 test measures the concentration of complement component 3, a protein at the center of the classical, lectin, and alternative complement pathways....
Complement C4 Test: High, Low, Normal Range, Autoimmune Disease, and Immune Meaning
The complement C4 test measures the blood concentration of complement component 4, a protein used early in the classical and lectin complement pathways. C4...
Complement C5 Test: Terminal Complement Pathway and Deficiency Risk
A complement C5 test evaluates the amount or function of complement component 5, the protein that connects upstream complement activation with two major outcomes:...
Complement C6 Test: Complement Deficiency and Infection Risk
The complement C6 test evaluates whether complement component 6 can perform its role in the membrane attack complex, the terminal structure that helps the...
Complement C7 Test: Complement Deficiency and Infection Risk
The complement C7 test assesses the function of complement component 7, one of the proteins that turns C5b-6 into a membrane-bound terminal complement complex....