Bovine IL-21 ELISA Kit

The Assay Genie Bovine IL-21 ELISA Kit enables quantitative measurement of Interleukin-21 in bovine serum and plasma samples using a sandwich ELISA format. IL-21 is a pleiotropic cytokine secreted primarily by activated CD4+ T helper cells, including Th17 and T follicular helper populations, where it regulates B cell differentiation, antibody class switching, NK cell maturation, and T cell proliferation.

This colorimetric assay is supplied as a complete 96-well microplate kit and is routinely used by laboratories studying bovine immune responses, vaccine efficacy, infectious disease models, and reproductive immunology in cattle. The assay is validated for serum and plasma matrices, providing reproducible standard curves for accurate cytokine quantitation.

For optimal performance, store kit components refrigerated at 2-8 °C and protect from light. Avoid repeated freeze-thaw cycles of reagents and samples. Standard incubation is performed at room temperature, and absorbance is read at 450 nm using a standard microplate reader.

Intended for research use only, this kit supports studies in veterinary immunology, livestock health, and inflammatory disease research in bovine models.

The Bovine IL-21 ELISA Kit from Assay Genie is built around pre-coated 96-well strip plates, so laboratories can run partial plates when sample throughput is limited. Each kit ships with a lyophilized recombinant bovine IL-21 standard, a biotinylated detection antibody, streptavidin-HRP conjugate, concentrated wash buffer, assay diluent, TMB substrate, and stop solution. The reconstituted standard is serially diluted across seven or more points to generate a standard curve in pg/mL, allowing interpolation of unknown sample concentrations within the dynamic working range.

For plasma preparation, EDTA and heparinized collection tubes are both compatible anticoagulants; citrate plasma may require independent validation since citrate chelation can shift recovery values. The recommended loading volume per well is typically 50–100 µL of prediluted sample and standards, and any sample reading above the highest standard should be re-assayed at a higher dilution rather than extrapolated. Typical intra-assay and inter-assay coefficients of variation fall below 10% and 15% respectively when protocols are tightly followed, supporting reproducible cytokine quantitation between batches and operators.

Beyond infectious disease and vaccine work, the assay is used in bovine mastitis research, bovine respiratory syncytial virus models, Mycobacterium avium subspecies paratuberculosis (Johne's disease) studies, and reproductive immunology projects where T follicular helper cell output is being characterized. Cross-reactivity with ovine or caprine IL-21 has not been formally characterized for this antibody pair, so the kit should be treated as bovine-specific. After incubation with TMB, the stop solution shifts the reaction from blue to yellow and absorbance is measured at 450 nm, ideally with a 570 nm reference filter subtracted for plate background correction. Wells should be read within 30 minutes of stopping to maintain consistent signal.