Immunofixation. III. Application to the study of monoclonal proteins.

We have shown how immunofixation can be successfully used to study proteins exhibiting electrophoretic polymorphism. An analogous situation is seen in the disorders of the immune system that result in the production of variable quantitites of homogeneous immunoglobulins. Immunoelectrophroesis has been heavily used--sometimes unsuccessfully because of poor resolution--to study these materials. The appearance of a monoclonal immunoglobulin band is identical in both immunofixation and standard gel electrophoresis, a feature that allows unambiguous identification of a protein as to its heavy-chain class and light-chain type. Because antigen and antibody are placed in contact almost immediately after electrophoresis, interfering diffusion does not occur and even extremely small bands can be demonstrated and characterized.