Immune response of rats to subcellular fractions of isologous brain and liver

The titres of complement fixing antibodies in the sera of rats injected with the soluble fraction of rat brain emulsified in Freunds' complete adjuvant (FCA) were usually below 10.

In contrast, injections of the nuclear, mitochondrial or microsomal fractions of rat brain in FCA were followed by the appearances of heat stable complement fixing and haemagglutinating antibodies within a few days, the highest antibody levels being attained about 6 days after the first injection of a particulate fraction. The microsomal fraction was the most efficient particulate antigen. After 2 weeks of immunization about 60 per cent of the complement fixing activity of the antisera was due to 19S antibody and the remainder to 7S antibody.

The response to injections of the nuclear and microsomal fractions of rat liver followed a similar time course but produced levels of complement fixing antibodies that were consistently lower than those engendered by the corresponding brain antigens.