Susceptibility and reactivity in polysensitized individuals following controlled induction.

BACKGROUND: It is uncertain whether polysensitized patients acquire multiple allergies only because of a high degree of exposure to environmental allergens, or because of being highly susceptible to developing contact allergy. OBJECTIVES: The aim of this study was to investigate and compare susceptibility and reactivity in polysensitized and monosensitized individuals, and in healthy controls. PATIENTS/METHODS: We sensitized 66 adult individuals (21 polysensitized, 22 monosensitized, and 23 healthy controls) with diphenylcyclopropenone and assessed challenge responses with visual scoring and ultrasound. We compared sensitization rates using a chi-square test and logistic regression analyses, and calculated linear regression lines of the elicitation responses for each individual. The mean values of the slopes and the intercepts for each group were used to measure the strength of the elicitation response, and were compared using the Mann-Whitney test. RESULTS: Sensitization ratio was equal in the three groups: 57% for the polysensitized, 59% for the monosensitized, and 65% for the healthy control group. There was a lowered elicitation threshold in the polysensitized group compared with that in the monosensitized and healthy control groups and, although not statistically significant, a stronger elicitation response was observed in the polysensitized group. CONCLUSION: Increased reactivity was found in the polysensitized group, demonstrated by a lowered elicitation threshold, compared with that in the monosensitized and healthy control groups.