Development of a semi-quantitative enzyme-linked immunosorbent assay (ELISA) for detection of human IgG subclass antibodies

We have developed a sensitive enzyme-linked immunosorbent assay (ELISA) which measures antibodies to bee venom phospholipase A2 (PLA2) and hyaluronidase (HYAL), horse IgG, bovine casein, and the bacterium Streptococcus mutans in each of the four human IgG subclasses. For this purpose, we have used mouse monoclonal antibodies (McAb) specific for each subclass and one which showed 'pan-IgG' reactivity. Binding to human IgG was similar for all the McAb and dilution of human IgG resulted in similar dilution curves for each subclass. Results were expressed as arbitrary U ml-1 by comparing the optical density obtained with each subclass-specific McAb to a reference curve for total IgG antibody constructed using the 'pan-IgG' McAb. Close agreement was found between the total amount of IgG antibody and the sum of the antibody in each of the four subclasses (PLA2 r = 0.90, horse IgG r = 0.98, bovine casein r = 0.84, S. mutans r = 0.85), confirming that these assays provide semi-quantitative measurements of the amount of subclass-specific antibody.