The cystatin C (CST3) antibody targets cystatin C, a low-molecular-weight protein encoded by the *CST3* gene. Cystatin C is a cysteine protease inhibitor that regulates proteolytic activity by inhibiting cathepsins, enzymes involved in protein degradation, immune response modulation, and extracellular matrix remodeling. It is expressed ubiquitously, with high levels in cerebrospinal fluid, blood, and tissues like the kidneys, brain, and immune cells.
CST3 antibodies are vital tools in research and diagnostics. In neuroscience, they help study cystatin C's role in neurodegenerative diseases, such as Alzheimer's, where it may reduce amyloid-β aggregation or exhibit neuroprotective effects. In nephrology, these antibodies detect cystatin C as a biomarker for renal function, offering advantages over creatinine in assessing glomerular filtration rate (GFR), especially in early kidney disease. Additionally, they aid in cancer research, exploring cystatin C's dual role in tumor progression—either suppressing metastasis by inhibiting proteases or promoting it via immune evasion.
Commercially available CST3 antibodies are used in techniques like ELISA, Western blot, and immunohistochemistry. However, variability in antibody specificity across isoforms or post-translationally modified forms requires careful validation. Ongoing research aims to refine their clinical utility, particularly in age-related and inflammatory conditions, highlighting cystatin C's expanding role as a multifunctional protein in health and disease.