Antibody-mediated cytotoxicity after measles virus infection

Antibody cytotoxicity in the presence of complement to measles virus-infected cells was determined in sera of individuals at various stages of measles virus infection. A measles virus carrier cell line, which possessed viral antigens on the cell membrane, was employed as target cells. The cytotoxic effect was measured by 51-Cr release from the measles virus-infected cells. A microtiter method was used to determine the titer of antibody cytotoxicity. Cytotoxic antibodies could be detected in serum specimens from individuals after natural measles virus infection and vaccination. Sera from subacute sclerosing panencephalitis (SSPE) patients had only slightly higher titers than were found in sera obtained from individuals 1 week to 3 months after measles virus infection. Sera from children inoculated with measles virus vaccine lost their ability to react in hemagglutination inhibition, neutralization (NT) and cytotoxicity (CT) tests after absorption with the hemagglutinin from measles virus. SSPE sera treated in a similar manner retained their activity in NT and CT tests. Cytotoxic antibody was, therefore, shown to be directed against the hemagglutinin and some other antigen of measles virus.