Induction of a hemolysin response in vitro. Interaction of cells of bone marrow origin and thymic origin.

The immune response to foreign erythrocytes was studied in vitro. Two subpopulations of cells were prepared. One was a population of bone marrow-derived spleen cells, taken from thymectomized, irradiated, and bone marrow-reconstituted mice; there was evidence that most of the precursors of the PFC had been present in this cell population, but few PFC developed in cultures of these cells alone in the presence of immunogenic erythrocytes. Another cell suspension was made from spleens of mice which had been irradiated and injected with thymus cells and erythrocytes; these cells were called educated T cells. The two cell suspensions together allow the formation of PFC in the presence of the erythrocytes which were used to educate the T cells, but not in the presence of noncross-reacting erythrocytes. If bone marrow-derived cells and T cells were kept in culture together with two different species of erythrocytes, and if one of the erythrocytes had been used to educate the T cells, then PFC against each of the erythrocytes could be detected.