DNCB Followed by Paranitrosodimethylaniline PNDMA

We initially sensitized 12 guinea pigs with DNCB (technique p. 4), verifying the sensitization after 14 days by a patch test which was strongly positive in all the animals. We subsequently sensitized them with PNDMA (technique p. 28). 

Two weeks after this second sensitization, we tested one flank with 0.1% DNCB in acetone and the other with 1% PNDMA in olive oil. The 2 patch tests were strongly positive (N. Hunziker and coll., 1964). Thus, we can say that previous sensitization with a strong eczematogen, such as DNCB, has not prevented further sensitization with a weaker eczematogen, as Landsteiner, Rostenberg and Sulzberger (1939) have also stated. 

Epstein and Kligman (1958), using the same 2 eczematogens in man, showed that sensitization with a strong eczematogen, such as DNCB, diminishes man s capacity to be sensitized with a weaker eczematogen, such as PNDMA. 

---