For measuring serum IL-6, are domestic or imported ELISA kits more reliable?

For selection, you can compare two or three domestic suppliers at the same time: Lianke, Sizhengbo, Dakewe, and Elabscience all offer IL-6 ready-to-use kits, and many are pre-coated plates plus ready-to-use standards. Ask sales about several key points: whether there are validation data for human serum samples, whether the sample volume is 50 or 100 microliters, the low-value quality control range, and how long the same lot number can be stored. Under 1500, prioritize a 96T full kit; do not buy antibody pairs that require self-coating, as there are too few samples to afford the time and cost of condition optimization.

There is indeed a gap between domestic and imported products for serum IL-6, but the key lies mainly in sensitivity at the low-concentration range and lot-to-lot consistency. Ready-to-use kits from imported brands such as R&D and BD usually give more stable recovery in low-value serum samples, but within a budget of 1500 for 96T, it is basically very difficult to obtain legitimate in-stock products. Among domestic ready-to-use kits from major manufacturers such as Lianke, Sizhengbo, and Xinbosheng, if sample dilution is well optimized for human serum IL-6, low-concentration recovery can also fall within an acceptable range. It is recommended to first buy a small domestic specification or apply for a trial sample, and perform linear dilution and spike recovery; do not judge only by the standard curve R².

To judge whether a kit is stable, don't rely on brand impressions. Instead, use your own samples to run three small experiments: first, perform a 2-fold serial dilution to check linearity; second, spike standard into low-value serum to check recovery; third, measure the same serum repeatedly across different plates to check inter-assay variation. When the budget is limited, a 96T kit from a major domestic manufacturer within 1500 is realistic, but before ordering, ask clearly whether it is ready-to-use, whether it includes standards and high/low controls, and whether it can provide a COA and batch quality control data.

A 50 µL sample run as a single well carries relatively high risk. Many IL-6 kits require 50 or 100 µL per well; if the undiluted sample is only enough for 1 replicate well, and given that low-concentration serum IL-6 itself varies greatly between individuals, a single well with an outlier cannot be rechecked. It is recommended to run at least replicate wells; if the sample volume is insufficient, dilute 1:2 or 1:3 and then run replicate wells. Use the sample diluent supplied with the kit rather than substituting PBS, otherwise matrix effects will affect recovery.