Medizym® Anti-ZnT8 is a chromogenic ELISA kit for the quantitative determination of auto-antibodies to zinc transporter 8 (ZnT8 Ab) in human serum. ZnT8 is a cellular zinc export protein that plays a key role in the accumulation of zinc within insulin secretory granules. Loss of ZnT8 activity, through auto-immune targeted destruction has been correlated with type 1 diabetes as well as the type 2 diabetes subtype latent autoimmune diabetes in adults (LADA), also called Type 1.5 Diabetes.
Reagents, composition, storage, and stability
- Microtiter plate. 12 breakable strips with 8 wells each (96 wells total) coated with ZnT8. The plate is supplied in a vacuum sealed bag with desiccant.
- Concentrated wash buffer. 125 mL of 10x concentrated wash buffer
- Streptavidin–peroxidase. 0.7 mL of 20x concentrated SA-POD
- Substrate. 15 mL of ready to use TMB.
- Stop Solution. 12 mL of 0.25 M sulfuric acid. Ready to use.
- SA-POD Diluent. 15 mL of ready to use dilution buffer
- ZnT8–Biotin. 3 vials of lyophilized biotin-conjugated ZnT8.
- ZnT8-Biotin Diluent. 2 vials of 15 mL dilution buffer. Ready to use.
- Negative Control. 0.7 mL of ready to use negative control
- Positive Controls. 0.7 mL each of 2 different positive control concentrations. Ready to use
- Calibrators. 4 vials, each of 0.7 mL of calibration material.
Type 1 diabetes, also known as insulin-dependent diabetes mellitus (IDDM), results from a chronic autoimmune destruction of the insulin-secreting pancreatic beta cells, probably initiated by exposure of genetically susceptible host to environmental agents. Autoimmune destruction of beta cells is thought to be completely asymptomatic until 80 – 90% of the cells are lost. This process may take years to complete and may occur at any time in all ages.
During the preclinical phase, this autoimmune process is marked by circulating autoantibodies to beta cell antigens. These autoantibodies, such as anti-insulin (IAA), anti-glutamic acid decarboxylase (GAD), anti-tyrosine phosphatase ICA 512 (IA2) and zinc transporter 8 (ZnT8), are present years before the onset of type 1 diabetes and prior to clinical symptoms.
ZnT8 autoantibodies are directed principally to the C terminal domain of ZnT8 (residues 268 – 369). Human population gene polymorphism at the codon for the 325th amino acid results in the expression of three protein variants: Arginine (R) 325, Tryptophan (W) 325 and very rarely Glutamine (Q) 325. ZnT8 autoantibodies may be specific to the R 325 or W 325 variant, or may be residue 325 non-specific. Sera that react with the Q allele only are extremely rare.
The Medizym® anti-ZnT8 ELISA is capable of detecting, and quantifying, autoantibodies specific to R 325 or to W 325, or to residue 325 non-specific variants.