Quantitative estimation by ELISA of IgG anti-D (RH1) in immunoglobulin preparations and in the sera of D-immunized donors.

Immunoglobulin preparations of anti-D (RH1) are injected to prevent haemoly tic disease of the newborn. Such preparations are obtained by the fractiona tion of plasma from immunized donors. Measurement of the concentration of I gG anti-D is required to estimate the potency of anti-D preparations and se ra from immunized donors. We have developed an ELISA method for the quantif ication of IgG anti-D. This method included the following steps, sensitizat ion of red cells by anti-D, solubilization of red cell membranes by Triton, and eventually, measurement of IgG anti-D concentration by ELISA. The inte rnational reference preparation of anti-D (68/419) was used as a reference. With this method, we measured IgG anti-D concentrations in 5 immunoglobuli n preparations of anti-D and in the sera of 10 donors immunized by D antige n. The ELISA results were compared with those obtained by automated hemaggl utination. A mean anti-D concentration of 56.2 mug/ml was found by ELISA in immunoglobulin preparations. Similar results were obtained by automated he magglutination (mean 52 mug/mL). In the sera of 10 D-immunized donors, anti -D IgG concentration varied from 2.2 to 59.8 mug/ml. A good correlation bet ween ELISA and automated hemagglutination was observed in these sera (r = 0 .98, p < 10(-7)). In conclusion, the ELISA technique offers an alternative to automated hemagglutination. It requires only the standard equipment nece ssary for immuno-enzymatic methods. (C) 2001 Editions scientifiques et medi cales Elsevier SAS.