Histological Control of Sensitization

Landsteiner and Jacobs (1935) adapted a descriptive notation following the exact aspect of the observed reaction. For simplification we adopted a standard scale following the common criteria used by many investigators Landsteiner and Chase (1940,1941), Nilzen (1952), Chase (1954), Rockwell (1955), and others. 

If only important differences are noted and if the test is always done under the same conditions, the macroscopic interpretation of the patch test is certainly of value. 

In order to avoid all risk of misinterpretation, the concentration of the substance used in the patch test must be lower than the minimum toxic concentration of that substance, but sufficient to trigger a reaction in the sensitized guinea pig. This concentration can be lower in the more sensitized animals than in those less sensitized. Guinea pigs have been shown to be sensitive to concentrations 10 to 20 times lower than the minimum toxic concentration (Sulzberger and Witten, 1954). However, man can react to concentrations 100000 times lower than the minimum primary toxic concentration (Wedroff and Dolgoff, 1935, and others). 

We would like to insist, as have Macher and Sennlaub (1963), that the main source of error which leads to misinterpretation lies in the very small difference between the minimum concentration of the solution used in the patch test for the specific reaction of sensitization and the minimum concentration producing a primary toxic effect. 

In every laboratory, in fact in all new experiments, these concentrations must be re-evaluated. 

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