ELECTRON MICROSCOPIC OBSERVATIONS ON LOCALIZATION OF ANTIGEN IN TUBERCULIN REACTION

Abstract

The tuberculin reaction was examined in the electron microscope using as antigen PPD conjugated to ferritin. The ferritin marker was rapidly localized within macro-phages prior to the time of significant lymphocyte accumulation. Evidence of degenerative changes in macrophages was seen. Uptake of marker by lymphocytes was not noted. Appropriate control experiments indicated that the uptake of antigen by macrophages and subsequent macrophage degeneration were not dependent on previous sensitization. The accumulation of lymphocytes without apparent contact with unaltered antigen was interpreted as evidence that lymphocyte accumulation was a consequence of the prior interaction between antigen and macrophages.