Structural homogeneity of human subacute sclerosing panencephalitis antibodies.

Three homogeneous immunoglobulin fractions were isolated from the serum of a patient with subacute sclerosing panencephalitis (SSPE). All three fractions reacted in immunodiffusion with measles and SSPE virus preparations. The amino-terminal sequence of the light and heavy chains of one of the antibody fractions was determined by automated Edman degradation. A single amino acid residue was obtained at every step, confirming the homogeneity of this human antibody.