The production of a “universal developer” for the immunological detection of human IgG and its application in immunodiagnostics

Summary

This study describes the development of a bispecific monoclonal antibody capable of the simultaneous recognition of horseradish peroxidase (HRP) and human IgG. This antibody, coded McC2, has been applied in a novel manner as a universal developing reagent for the detection of human IgG. McC2 cross-reacts with all human IgG subtypes and was found to recognise an epitope on the Fe portion of human IgG. McC2 does not cross-react with human IgM or IgA. This bi-specific antibody belongs to the mouse IgG₁ subclass. McC2 was used for the detection of human IgG in a simple one step enzyme-linked immunosorbant assay (ELISA). Use of this bi-specific antibody in this assay resulted in an excellent signal to noise ratio with background in negative control wells virtually nonexistent. McC2 was also applied in a clinical diagnostic test for the detection of auto anti-nuclear antibodies in patient sera. McC2 was substituted, in a blind study, for a HRP-conjugated second antibody supplied with the test kit. All sera were tested both with the kit's second antibody and McC2. When using McC2, we obtained no false positive results whereas five false positives were obtained when using the kit's second antibody. However, one false negative result was obtained with the use of McC2 as a developing reagent while none were noted with the use of the kit's second antibody.

This study demonstrates the potential use of bi-specific “universal developers” in a wide variety of immunobased techniques as well as the potential advantages for the production of a complete panel of bi-specific developing monoclonal antibodies against IgGs from a number of different species.