Looking for recommendations for a mouse IL-6 ELISA kit to measure serum and cell supernatant.

From a practical standpoint, it is best to test all 80-plus samples in a single batch with the same lot number, run two plates together, and include a standard curve on each plate. Do not cut corners by running a standard curve on only one plate. Order one extra plate as a backup to avoid issues from plate washing or pipetting errors. If the budget is within 30 per well, in my personal experience domestic kits are more likely to meet this, but imported kits with discounts or certain distributors' customs-cleared stock may also come close. When asking about stock availability, have the distributor directly shoot a warehouse video or provide the shipping warehouse address; do not rely solely on the system showing "in stock." We previously encountered a case where the page showed in stock but it was actually being transferred from overseas.

If you are using a certain brand for the first time, it is recommended to buy 2 boxes, or at least 1 box plus standard/quality control replicates, and first run 2-3 positive and 2-3 negative samples to see whether the low-value end is stable. Do not run all 80-plus samples directly, otherwise if there is a problem with the background or linearity, the entire batch will be wasted. In terms of brands, domestic Xinbosheng is relatively comprehensive for inflammatory factor testing, and Lianke and Elabscience are also common; imported R&D is the reference method but is expensive, suitable for cross-validation. In terms of supply chain, prioritize authorized distributors with local inventory, and you may request shipment in batches.

Our laboratory primarily uses domestic products. For over 80 samples, I will prioritize pre-coated, detachable 8-well strips or single-well plates to avoid coating an entire plate at once. Within a budget of 30 per well, domestic brands such as Lianke, Xinbosheng, and Elabscience can negotiate for in-stock items; imported R&D, BioLegend, and Invitrogen typically exceed the budget when calculated per full box, unless someone splits the box. When selecting, do not only look at the nominal sensitivity. Ask the distributor for the inter-batch CV and standard curve range of that specific lot, and require a minimum of two boxes from the same lot number to be shipped, to avoid inter-batch variation introduced by measuring serum and cell supernatant in separate batches.

Serum and cell supernatant are two different matrices, so it is recommended to first perform small-sample dilution linearity testing. After macrophage supernatant stimulation, IL-6 may reach hundreds or even thousands of pg/mL, while serum is generally lower, so the supernatant can first be diluted 1:5 or 1:10, and serum 1:2 or 1:4. Regarding kits, I pay more attention to a minimum detection limit around 2-5 pg/mL and good discrimination at the low points of the standard curve. I have used domestic 4A Biotech and Lianke to measure mouse IL-6, and the reproducibility was acceptable; for imported kits, if in stock, Invitrogen's Ready-Set-Go system can be used by splitting components yourself, but pay attention to the coating antibody lot.