[Anti-D quantification by an enzyme-linked antiglobulin test: A comparison study of two methods]

ABSTRACT

The quantification of anti-red blood cell antibodies routinely performed by standard direct antiglobulin test [DAT], but there are some limits to its sensitivity and the end-point evaluation is very subjective in this method. Recently, a modified enzyme-linked immunosorbent assay [ELISA] has been applied to detect anti-red blood cell antibodies. In this method, the end-point is determined by enzyme activity of an enzyme conjugated anti-human antibodies. The enzyme converts a soluble substrate to a soluble colored product, which is proportional to amount of primary antibodies. This technique has been called enzyme linked antiglobulin test [ELAT]. In this study, we tried to evaluate the analytical parameters of this technique and compare with conventional DAT method. Our results showed some modification of the previously described ELAT technique makes it feasible and simpler for the routine applications. This modified method was reproducible with the mean coefficient variation of 9.08 and 5.21 for between days and within day assays and found to be at least sixteen times more sensitive than DAT method. Anti-D measurement showed an acceptable correlation [R 0.88] between ELAT and DAT methods. Therefore, this method could be useful for more precise monitoring of allo-immunized mothers and patients with autoimmune hemolytic anti-D anemia and provide an alternative method for assessing anti-D activity of specific total IgG and IgG subclasses preparation