Tuberculin (P.P.D.) and cortisone acetate, singly and in combination, were added to explanted splenic tissue derived from guinea pigs, mice, and rabbits, and buffy coats obtained from rabbits. These tissues came from normal animals or from animals which had been infected with the tubercle bacillus or immunized with killed tubercle bacilli.
5 µg./ml. of tuberculin or 0.5 µg./ml. of cortisone was the largest concentration of the respective reagents which was tolerated by cultured cells from normal animals.
From the results with all tissues studied it would appear that P.P.D. selectively damaged only the growing cells of splenic tissues from sensitive guinea pigs and to a lesser degree the migrating cells of buffy coats obtained from sensitive rabbits.
Cortisone appeared to have increased toxicity for only explanted splenic cells from tuberculin-sensitive guinea pigs.
The specific effect of P.P.D. on tissues from tuberculin-sensitive animals was not modified by cortisone under the conditions of these experiments. Thus these data furnished no evidence that cortisone had any direct effect on the response of the sensitive cells to P.P.D.