Analysis of anti-HAV antibodies in IG preprations. Semi-quantitative analysis of anti-HAV antibodies in the immune globulin preparations was performed with the HAVAB EIA kit. Ten-fold serial dilutions of the Lab 1, Lab 2, and WHO standard IG preparations in complete medium were tested in duplicates for the presence of anti-HAV antibodies. The negative control plasma control was also tested. The cutoff value was obtained from control reagents included with the HAVAB EIA kit. In this competitive assay, values above and below the cutoff were considered negative and positive, respectively. The means of duplicate determinations are plotted and the standard deviations are shown as bars.