The identification of the subclasses of human IgG by analytical isotachophoresis.

A new method is described for demonstrating the individual subclasses of human IgG immunoglobulins by means of analytical isotachophoresis. Individual subclasses of IgG purified from sera of multiple myeloma patients have distinct mobility patterns. When a mixture with purified IgG for each of the 4 subclasses is analyzed, a characteristic mobility pattern with 4 unique peaks is obtained. An IgG of unknown subclass can be identified by the superimposition of the peak for the unknown upon one of the 4 well characterized peaks. The method using microgram quantities protein in a 1.0 microliter volume can be performed easily in 15 min.