In vitro cross-reacting antibodies from rabbit antisera to rat brain synaptic membranes and thymocytes.

Rabbit anti-rat brain synaptic membrane and anti-rat thymocyte antisera were used in cytotoxicity, immunofluorescence, and absorption assays to define the antigenic relationship between the rat brain and thymocytes, and the localizing properties of antibodies. Both antisera cross-reacted with brain tissue and thymocytes. However, anti-synaptic membrane and anti-thymocyte antisera also contained antibodies specific for neurons and thymocytes, respectively. Immunofluorescence showed that antibodies from anti-thymocyte antiserum reacted with antigenic determinants situated on the surface membrane of brain cells.