Relative Functional Binding Activity of IgGl and IgG3 Anti‐D in IgG Preparations

Publisher Website
Google Scholar
Abstract
The intention to replace polyclonal IgG anti‐D with human monoclonal antibody in the prophylaxis of haemolytic disease of the newborn requires knowledge concerning the relative content of IgGl and IgG3 anti‐D in prophylactic IgG preparations that are in present use. This has been carried out using a functional assay in which the absolute amount of IgGl and IgG3 anti‐D present on red cells was determined after incubation with IgG preparations. The assay was carried out by flow cytometry on 17 samples; expressed as a percentage of the total, the average value for the amount of IgG3 anti‐D on the cells was 8% (range 1–18%). Similar measurements were also made on the anti‐D present in 18 samples of antisera; IgG3 anti‐D formed a larger fraction of the total, the average value being 17% (range 0–60%) confirming previously reported estimates. It is suggested that some of the low values found for IgG3 in IgG preparations may be due do preferential loss during production.