Sensitization by multiple applications on the nipple

In order to demonstrate a general sensitization, most of the experiments on the guinea pig that we have described up to now were performed on animals whose sensitization was effected at a determined place (the neck) and in whom triggering of the eczema (a single application) took place at a location never previously in contact with the eczematogenic substance (flank or nipple). However, contact eczema in man is most often due to repeated contact of the eczematogenic substance on the same site. 

It would be interesting to know when the eczematous lesions appear at the location where the multiple sensitizing applications are performed. It would equally be interesting to know when the acanthosis appears and if there is a relation between the two phenomena (Golay and Brun, 1958). 

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. 

After 3 applications there are no eczematous lesions, on the nipple, or on the flank and no acanthosis is observed. 

After 8 applications, spongiosis appear on the epidermis of the flank and even more so on the epidermis of the nipple. A light dermal infiltrate of similar appearance is evident both on the flank and on the nipple there is a clear acanthosis on the flank, but its appearance on the nipple is difficult to note in view of the intensity of the eczematous, epidermal lesions. 

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