A new simple method of evaluating specific cytotoxicity to tuberculoprotein in the study of tuberculin hypersensitivity in vitro by comparing cell populations is presented. Utilizing this technic it was possible to reproduce Rich's results (1, 2) using human tissues of reticuloendothelial origin. The demonstration of the specific cytotoxic phenomenon in tuberculin-sensitive human tissues indicates that the principle elaborated by Rich (2) of specific changes in the individual fixed tissue cells in tuberculin hypersensitivity, possibly related to cellular antibodies, applies to human subjects as well as to the animals heretofore studied.
Preliminary observations suggest that macrophages from donors with clinically active tuberculosis are more sensitive to tuberculoprotein than macrophages from tuberculin-positive donors without clinically active disease.
Macrophages from tuberculin-positive donors appeared to be more sensitive to tuberculoprotein than fibroblasts derived from the same tissue. An inhibition of cell proliferation was seen when both cell types were exposed to PPD. In addition macrophages responded to tuberculoprotein with gross morphological changes and eventual cytolysis.