Is the sensitivity of the mouse TNF-α ELISA kit sufficient for measuring serum and splenocyte supernatant?

If you are concerned about low TNF-α in the supernatant, it is recommended to prioritize a high-sensitivity version or a kit that can provide validation data for cell supernatants. If splenocyte supernatants are not stimulated, TNF-α is often in the range of a few to several dozen pg/ml, and a standard kit may fall right near the lower limit of detection, making the measurement unreliable. You may consider stimulating with LPS or ConA for a short period before collecting the supernatant, or moderately concentrating the supernatant; however, concentration will also enrich salts and contaminating proteins at the same time, so recovery validation is required. The standard curve range should be confirmed for the specific lot; generally, the highest point is 500 or 1000 pg/ml, and the lowest point is no higher than 7.8 pg/ml. Before purchase, you may request the CoA for that lot to check the precision at the low point.

Do not simply follow the manual for predilution factors. It is recommended to perform your own serum dilution linearity: take 2-3 high-value serum samples, dilute at 1:2, 1:5, and 1:10, and check whether the results fall in the middle range of the standard curve and whether recovery is 80-120%. Splenocyte supernatants can be measured both neat and at 1:2. If the expected value is below 10 pg/ml, even if a conventional kit states an LOD of 1 pg/ml, repeatability is often poor, so consider a high-sensitivity kit. Standard curve ranges vary by brand; common maximum values are 500 or 1000 pg/ml, and the lowest point is 7.8 or 15.6 pg/ml. Before purchasing, ask the sales representative to provide real sample data, especially parallelism for serum and culture supernatants.

Whether the sensitivity is sufficient ultimately needs to be tested with your own samples; it is advisable not to rely solely on the manufacturer's promotional claims. You can ask the supplier to provide trial samples and test several samples each with your serum and splenocyte supernatant to check spike recovery and precision at the lowest point. When the sample size is 40-50, it is recommended to choose detachable strips to avoid wasting a whole plate in one use. For cross-plate comparison, it is best to include the same quality control serum or supernatant on each plate to monitor inter-plate CV. In addition, ask clearly about the kit's tolerance to hemolyzed and lipemic samples; hemolysis in serum samples may affect TNF-α detection. The standard curve range and LOD should be confirmed in the report for the same lot, and do not substitute data from an old lot.

For serum, it is generally recommended to perform a 2-5 fold dilution first rather than loading neat samples directly, because the serum matrix causes significant interference with color development. Splenocyte supernatants can usually be measured directly, but if unstimulated or weakly stimulated, they may fall below the limit of quantification; it is advisable to test both neat and 1:2 dilutions. Standard curves commonly range from 7.8-500 pg/ml or 15.6-1000 pg/ml, and the minimum detection limit is mostly 1-4 pg/ml, but the lower limit of quantification is often higher, so it is important to ask the manufacturer specifically about the LOQ rather than the LOD. For your 40-50 samples, a 96T plate is sufficient, but you need to reserve wells for the standard curve, blanks, and quality controls. It is recommended to first perform spike recovery and dilution linearity on 2-3 representative samples.