The production of antigens in sufficient amounts and of the desired quality is often the critical step in the development of a new test system. In particular, the purification is often difficult and causes delays in the development process. This may be due to different reasons:

• The antigen is located in the cell membrane: To eliminate the molecule from the membrane, aggressive methods are often required which may destroy the antigen.
• The antigen must be in its native, three-dimensional form. If the antibodies to be detected bind to conformational epitopes of the antigen, it needs to be purified in its native state, a procedure which is very complicated and complex.

In these cases, a genetic method for the production of antigens is by far quicker. In the RC-IIFT method, the antigen-coding DNA sequence is inserted into a DNA molecule (plasmid) which is afterwards introduced into suitable host cells. The cells express the antigen molecule and can thus be immediately used as a substrate in the immunofluorescence test. Using this method, test systems with new antigens can be produced in a short time.

The following EUROIMMUN test systems are based on the RC-IIFT method:

*currently not sold as IVD in the EU   **under development