[Studies on the interaction between cells infected with measles virus and anti-measles antibody. I. Cytotoxic antibody activity of sera obtained from patients with natural measles and subacute sclerosing panencephalitis by use of chronically infected cell lines].

Sera obtained from patients with natural measles and subacute sclerosing panencephalitis (SSPE) showed cytotoxic activity in the presence of complement on cells persistently infected with either measles virus (Schwarz and TYCSA strains) or SSPE virus (Halle and Mantooth strains). The cytotoxic activity was demonstrated in both IgG and IgM fractions of measles convalescent sera, but only in IgG fraction of SSPE sera. Measles convalescent sera completely lost the cytotoxic activity to all carrier cell lines, when absorbed with any one of the cell lines, indicating that the viral surface antigens of these cell lines infected with measles or SSPE virus were identical. On the other hand, the cytotoxic activity of SSPE sera could not be readily absorbed with these cells. Thus, the affinity of SSPE sera for the viral surface antigens might be lower than that of measles convalescent sera.