Immunoglobulin G from subacute sclerosing panencephalitis brain as an immunological reagent.

Proteins were extracted at pH 2.5 from carefully washed brain homogenates of patients with subacute sclerosing panencephalitis. Immunoglobulin G was isolated from the extracts by gel filtration and immunoadsorbent chromatography and was 125I radioiodinated. The labeled immunoglobulin G was reacted with purified measles virus antigens by crossed immunoelectrophoresis and utilized to identify antigens in measles-infected cell cultures and hamster brain tissue subjected to treatment corresponding to that used for elution of immunoglobulin G. The method described is useful in identifying the specific nature of antibodies as well as antigens in tissue-associated immune complexes.