The induction of a "Mitsuda" type response by purified protein derivative (PPD) in tuberculosis

The present investigation was undertaken to study the kinetics and the histology of the reaction induced by purified protein derivative (PPD) from hii. tuberculosis by following skin test reaction for 21 days after induction. A total of 150 patients who were diagnosed to have cutaneous tuberculosis were given ITU PPD RT23 intradermally in the forearm. It was found that the induration was maximal on day 3. Although the induration started subsiding thereafter, it was more than 10 mm on day 21 in 65 of the 150 patients. The skin test site was biopsied from 8 of these patients on day 3 and from 15 patients on day 21. On day 3, the biopsy showed a predominantly lymphocytic infiltration with an admixture of monocytes, while on day 21, it showed a well-organized, epithelioid cell, giant cell granuloma with a mantle of CD8 positive T lymphocytes. The possible significance of this Mitsuda type reaction is discussed in this communication.