Abstract
Old Tuberculin and standard purified protein derivative were found to produce a specific inhibition to migration and to cause injury to tuberculous leukocytes. Injury to the cells also occurred, as seen by granulation, agglutination, vacuolization, and disintegration. Tuberculin nucleic acid, commercial thymus nucleic acid, and a highly purified thymus nucleic acid produced no significant inhibitory effect on tuberculous leukocytes.