CONTACT-TYPE DELAYED HYPERSENSITIVITY IN INFANTS AND CHILDREN: INDUCTION OF RHUS SENSITIVITY

The frequency of contact sensitization to a Rhus allergen, pentadecyl catechol, was determined in 102 infants and children 1 month to 8 years of age. Children between 3 and 8 years were readily sensitized and showed a depth of sensitivity and intensity of reaction comparable to that seen in adults. Infants below the age of 1 year had a markedly depressed ability to react to Rhus allergens. Children between 1 and 3 years old assumed an intermediate position, being more reactive than infants, but less so than older children. Theoretically these observations suggest that the mechanism of delayed hypersensitivity matures more slowly than other processes of immunity and resistance. Clinically the findings mean that lack of exposure is a more important factor than lack of susceptibility in explaining the diminished incidence of clinical Rhus sensitivity in children below the age of 8 years.