In vitro induction of the graft-versus-host reaction

1. 1. Using an in vitro method of analysis, the graft-versus-host reaction in mice has been studied. 2. 2. Previous observations made in vivo for graft-versus-host reactions, including timing of the onset of immunological maturity and the effects of irradiation, have been confirmed in this in vitro system. 3. 3. The host component of the graft-versus-host reaction has been analyzed by use of an intervening millipore filter barrier. Splenomegaly and associated histological changes can be induced in the absence of actual entry of adult spleen cells into the explanted test fragment. 4. 4. Additional experiments involving quantitative aspects of the reaction are described.