Quantitative dinitrochlorobenzene contact sensitization in a normal population.

Using a quantitative method based on the sponteneous flare phenomenon, contact sensitization to DNCB was studied in 143 healthy volunteers between the ages of 20 and 80 yr. A spontaneous flare reaction occurred in 96·5% of subjects tested, regardless of age, and a correlation was demonstrated between the intensity of the primary response to DNCB and the threshold dose of DNCB required to elicit an anamnestic response. The results are in striking contrast to a 40% incidence of spontaneous flare reactions previously found in cancer patients using the same method. These findings show that this method of assaying reactivity to DNCB detects abnormalities of cell-mediated immunity not demonstrated by qualitative methods.