Studies on antigen-binding cells. I. The origin of reactive cells

The origin of rosette-forming cells of mice immunized with sheep red blood cells has been investigated. By the use of antigenic markers on thymus cells (H-2, θ) it was shown that a considerable proportion of RFC formed in the spleens in irradiated animals reconstituted with thymus and bonemarrow cells, as well as in intact normal and immunized animals were of thymus origin. The possible limitations of the test systems and the significance of the results have been discussed.