The use of subcellular fractions to raise anti-lymphocytic serum.

Subcellular preparations of mouse thymocytes were compared with respect to their power to raise in rabbits antisera which prolonged the survival of skin homografts. Of the fractions studied thymocyte membrane' gave the most consistently good results, whereas thymocyte mitochondria' gave rise to sera which were toxic in high dose. Whole mouse liver homogenate or liver subcellular fractions did not elicit potent antisera. It is concluded that thymocyte `membrane' best fulfils the requirements for an ideal material for immunization thus far studied and provides a convenient starting point for further purification.