Tissue typing by mixed culture of lymphocytes. I. Demonstration of intracellular localization of transplantation antigen and H-2 antigen differences by the mixed cultures with addition of whole homogenate or ultracentrifuged fractions of mouse lymph-node cells

1. The cells used in the present experiments were lymph-node cells from inbred mice, and over 98 % cells were proven to be small lympho-cytes. Therefore, those cells that have undergone blastformation are all those derived from small lymphocytes. 2. When homogenate of one cell group is cultured with live cells of the other pairing group, there occurs blastformation. In the presence of PHA, such a blastformation becomes more marked. 3. The optimal concentration of PHA (phytohemagglutinin)-M added to the mixed culture is found to be 1% (v/v). 4. The maximum rate of blastformation in the mixed culture is observed at the culture hour 48, being much faster than in the mixed culture between two live cell groups. 5. In the mixed cultures between subcellular fractions prepared from cell homogenate by centrifugation and live cells, the transplantation antigenic potential (histocompatibility antigenic potential) is seen in the mitochondrial and the microsomal fractions, especially marked in the latter. 6. In the observations carried out by various combinations of these inbred mice, it has been demonstrated that the rate of blastformation induced by the addition of cell homogenate or sediment fractions prepared from the homogenate reflects quite accurately the differences in H-2 antigens.