[An enzyme-linked immunosorbent assay for determining serum anti-themocyte globulin concentration].

Objective: To establish an enzyme-linked immunosorbent assay (ELISA) for determining anti-themocyte globulin (ATG) levels in serum samples.

Methods: The microplate was coated with mouse anti-rabbit IgG monoclonal antibody, and sheep anti-rabbit polyclonal antibody conjugated with HRP was used as the second antibody for detecting the serum ATG levels in patients undergoing allogeneic hematopoietic stem cell transplantation.

Results: The optimal concentration of the coating antibody and dilution ratios of the serum samples and IgG-HRP conjugate were 0.2 microg/ml, 1:40 and 1:2500, respectively. The lower sensitivity limit of the assay was 31.25 ng/ml for ATG detection. A linear relationship was established within the concentration range from 40 to 1000 ng/ml, with the coefficients of variation of 7.91 within assay and 5.22 between assays, respectively. Seven patients undergoing stem cell transplantation with ATG pretreatment showed gradually decreased concentration of ATG, and after 90 days ATG could still be detected.

Conclusion: The sandwich ELISA we established provides a specific and sensitive method for quantitative measurement of ATG in the clinical setting. In patients undergoing stem cell transplantation with ATG pretreatment, the ATG concentration gradually decreases but remains detectable 90 days after the administration.