Anhydride CA Followed by Dinitrochlorobenzene DNCB

We successively caused sensitization with CA and then with DNCB (technique p. 32 and 4). Patch tests with CA on one flank and DNCB on the other are both positive under macroscopic examination. 

We then wondered if there would be a histological difference between the 2 tests, since, as we have seen, the infiltrate with the CA test in guinea pigs sensitized only to CA, is largely composed of eosinophils while the infiltrate of the test with DNCB in guinea pigs sensitized only to DNCB is composed largely of small round cells (lymphocytes). 

We should continuously keep in mind that guinea pigs sensitized to CA and subsequently to DNCB have a blood eosinophilia which is due to the first sensitization with CA (p. 45). We believe that some of these blood eosinophils are then fixed at the site of the patch test with DNCB. 

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