MIXED LEUCOCYTE REACTION - AN IN VITRO MODEL FOR HOMOGRAFT REACTION

Experiments have been performed to study the immunological reactivity of lymphocytes cultured under conditions of the mixed leucocyte culture using rat leucocytes. It was found that cells from parental strain rats, cultured in the presence of semiallogeneic F strainleucocytes, produced a greater degree of graft-versus-host reaction in 7- day-old F hosts than did corresponding parental cells cultured alone. This increased immunological reactivity can be demonstrated in cultures of 48-70-hr duration, but parental cells in 24-hr-old mixedleucocyte cultures did not show an enhanced reactivity.These experiments demonstrate that cells in the mixed leucocyte culture become sensitised against allogeneic transplantation antigens but that the process of sensitisation requires a period of at least 24 hr for its initiation. © 1969 by The Williams and Wilkins Co.