Primary non toxic solution

Using a primary non toxic solution of DNCB for sensitization, de Weck and Brun (1956) obtained negative results in summer but their results were positive in winter. These experiments should be repeated. 

After 8 daily applications we observed a clear sensitization in some guinea pigs, demonstrated by the patch test on the flank (out of 10 tests, 5 were positive). After 20 to 40 applications on a single nipple, the patch tests on the flanks are positive in almost all of the guinea pigs. Therefore, a general sensitization occurs even though the multiple applications are performed on a very small surface and with a primary non-toxic solution of DNCB (Table 1). 

As in a certain number of our experiments, some investigators used primary toxic solutions of DNCB others employed primary non-toxic solutions of DNCB, as we did in some of our experiments. There are many technical differences (concentration, number of applications) in addition to numerous variations in the results obtained by experimentation on guinea pigs in different laboratories as well as in the same laboratory. 

According to most authors, and our studies, a 0.1% primary non-toxic solution of DNCB in acetone causes no macroscopically visible reaction and no histological alterations on the flank and the nipple of guinea pigs. 

Guinea pigs can also be sensitized by regular, simultaneous applications of a 0.1% acetonic solution of DNCB (primary non-toxic) on both nipples and both flanks (Frey, 1951). 

The 2 flanks of unsensitized guinea pigs ate shaved. Every day a primary non-toxic acetonic solution of 0.1 % DNCB, is applied both to the 2 flanks and the 2 nipples. A biopsy of the flank and of the nipple is performed after 3, 8, 10, 12 and 16 applications. 

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