Product description

Human IL-21 ELISA (Enzyme-Linked Immunosorbent Assay) Kit is an in vitro enzyme-linked immunosorbent assay kit used for quantitative determination of IL-21 in serum, plasma, and cell culture supernatants. Specific anti-IL-21 antibodies are pre-coated onto high-affinity enzyme plates. Standards and samples are added to the wells of the enzyme plate, and after incubation, IL-21 present in the sample binds to the solid-phase antibody. After washing to remove unbound substances, a detection antibody is added for binding and incubated, followed by washing, and then the enzyme complex (Streptavidin-HRP) is added for binding and incubated. After washing, a colorimetric substrateTMB is added for color development, avoiding light. The intensity of the color reaction is proportional to the concentration of IL-21 in the sample. The reaction is terminated by adding a stop solution, and the absorbance is measured at 450 nm wavelength (with a reference wavelength of 570 - 630 nm).

Human Interleukin-21 (IL-21) is a type I cytokine that regulates the functions of T cells, B cells, NK cells, and myeloid cells. IL-21 is produced by activated follicular helper T cells (Tfh), Th17 cells, and NKT cells. IL-21 derived from Tfh cells plays a crucial role in the development of humoral immunity through its autocrine effects on Tfh cells and paracrine effects on immunoglobulin maturation, plasma cell differentiation, and memory B cells. Mature human IL-21 consists of 133 amino acids and shares 63% and 61% sequence identity with mouse and rat IL-21, respectively. IL-21 is closely associated with clinical conditions such as cancer immunotherapy, viral infections, and allergies. It also inhibits skin hypersensitivity reactions by limiting the production of allergen-specific IgE and degranulation of mast cells.

 

Specifications

Item Number	P162019S / P162019E
Specification	48 T / 96 T
Detection Range	15.63-1000 pg/mL
Detection Method	Sandwich ELISA
Detection Species	Human
Detection Time	4.5 hours
Sensitivity	8.16 pg/mL
Dilution Linearity	81 - 117%
Recovery Rate	76 - 121%
Intra-assay Variability	3.3%
Inter-assay Variability	5.0%

 

Components

Component Number	Component Name	Storage Temperature	P162019S	P162019E
P162019-A	Plate	2~8℃	48 T	96 T
P162019-B	Standard	2~8℃	1 tube	2 tubes
P162018-C	Detection Antibody	2~8℃	120 μL	240 μL
P162019-D	Enzyme Conjugate	2~8℃(Avoid Light)	30 μL	60 μL
P162019-E	5x Dilution Buffer	2~8℃	8 mL	15 mL
P162019-F	20x Wash Buffer	2~8℃	25 mL	50 mL
P162019-G	Substrate Solution	2~8℃(Avoid Light)	8 mL	15 mL
P162019-H	Stop Solution	Room Temperature	5 mL	10 mL
P162019-I	Plate Sealers	Room Temperature	3 pieces	5 pieces

 

Storage

The assay kit can be stored at 2~8℃. Alternatively, the reagents can be stored according to the storage conditions provided in the component information to avoid contamination and repeated freeze-thaw cycles. Diluted working solutions should be used immediately and not reused. The shelf life is 1 year.

Table 1. Reagent Storage Table After Initial Use

Material Name	Storage Conditions
Plate	Unused strips can be returned to the aluminum foil bag, tightly sealed, and stored at 2~8°C to avoid moisture absorption.
Standard	Use within 48 hours after dissolution, store at 2~8°C to avoid contamination.
Detection antibody	Use within 48 hours after dilution, store at 2~8°C to avoid contamination.
Enzyme conjugate
5x Dilution Buffer	Store at 2~8°C for 1 month, avoiding contamination.
20x Wash Buffer
Substrate solution	Store at 2~8°C for 1 month, avoiding light exposure.
Stop solution	Can be stored at room temperature.
Plate sealing film