What is the correlation between domestic ELISA kits for measuring serum IL-6 and imports?

Lianke, Xinbosheng, and Dake have been applied to IL-6 and TNF - α in rats. When comparing with samples from the same batch of R&D, it is recommended to select 20-30 cases covering high, medium, and low concentrations for Passing Bablok or Blank Altman to observe slope, intercept, and bias. If the main focus is on low concentrations of bronchoalveolar lavage fluid, the recovery rate and repeatability of low-end standard curve points should be emphasized. The linear range of domestic reagent kits may be slightly narrow, and the minimum quantification limit should be based on typical data from sales, not just the standard curve R ² on the instruction manual.

Domestic ELISA standard kits generally have 7 points, with 2 wells for each point. Some brands may have 8 or 6 points, depending on the instructions. During operation, the standard curve should have 2 wells per point. For samples, a single well can be made first, and for key low concentration samples, multiple wells should be made. The washing of the board should be consistent, and using a washing machine is more stable than manual tapping to avoid uneven temperature in the edge holes. It is not recommended to mix imported and domestic reagent kit samples completely in the same plate, but it should be completed on the same day as much as possible, and the incubation time and color development time should be measured using the same timer. If drift is found, calibrate with in board controls or duplicate samples.

In terms of price and lead time, non-custom domestic ELISA kits are usually cheaper than R&D, but there is a big difference between 96T and 48T, and whether they are imported and aliquoted. For 120 samples, it is recommended to buy at least 2 boxes of 96T and leave enough margin for replicates and the standard curve. Ask clearly whether it is in stock or needs to be transferred; generally, it can arrive within one week from a Shanghai warehouse, but some specific targets, such as those dedicated for rat bronchoalveolar lavage fluid, may require scheduled production. After arrival, check whether the lot number, expiration date, and instructions are consistent with the target to be measured. Reconstitute and aliquot the standard curve dry powder and standard according to the instructions and store at -20°C to avoid repeated freeze-thaw cycles. You can first request quotes and trial samples from three companies, then lock in one company for the entire batch.

Low-concentration recovery and linear range are the most problematic points in domestic substitution. It is recommended to perform spike recovery: take 3 aliquots of low-value serum, add standards at different concentrations, and calculate the recovery rate; meanwhile, perform serial dilution and examine the deviation between measured values and theoretical values. If the matrix difference between bronchoalveolar lavage fluid and serum is large, it is best to validate the two matrices separately. A sample size of 120 is sufficient. First arrange comparison of 10 samples from the same batch using both kits, and after confirming that the slope and deviation are within an acceptable range, use the domestic kit to test all remaining samples, so as to avoid the entire batch of data being incomparable.