Figure 3. IgG antibody activity to 2-hydroxyethylmethacrylate (HEMA) when conjugated to a carrier that was not used in the immunizations: ovalbumin (OVA). Sera were taken from animals immunized with mouse serum albumin (MSA) carrying various numbers of (HEMA) molecules: 3, 7, 15, or 22, respectively. Displayed are also control groups immunized with unconjugated MSA or adjuvant alone. IgG antibody activities are expressed in arbitrary ELISA units as compared with a standard included in each of the assays. The IgG antibody activity to OVA has been subtracted. Each dot represents 1 animal, and the horizontal bars indicate median values (n = 8 for all groups, except for the one given MSA_H22, where n = 7). Antibodies that could bind to HEMA, regardless of the carrier, were mainly induced by MSA carrying 15 or more HEMA molecules. The Mann Whitney U-test was used in statistical comparison between animals immunized with MSA_H3 and those immunized with MSA_H22.