[Investigation of the delayed type hypersensitivity reaction in atopic patients]

In the last decades the prevalence of atopic diseases has increased highly in developed countries. Although the reasons for this increase are not clear, it has been hypothesized that a reduction in infections and immunization programs may contribute to the increased prevalence of atopic diseases.

In the present study the relationship between tuberculin response and atopic disease was investigated.

A total of 1012 children vaccinated with BCG were included in the study. All the children were given five tuberculin units PPD, and PPD indurations were recorded after 72 h. The test result was considered to be positive if the induration size was greater than 9 mm. The atopic anamnesis (atopic dermatitis, rhinitis, conjunctivitis, asthma, urticaria) in the children and their families were investigated using a questionnaire.

608 individual (60.1%) had positive and 404 (39.9%) had negative tuberculin test. Positive atopic personal anamnesis was found in 31.74% in children with positive tuberculin skin test, whereas 39.85% was found in children with negative tuberculin test (p < 0.009, Fischer-test). Similarly more positive family anamnesis for atopic diseases was found among children with negative tuberculin test. In children with negative tuberculin test the prevalence of allergic conjunctivitis and rhinitis was significantly higher as compared to the group with positive tuberculin test.

The authors found an inverse correlation between tuberculin response and atopy status. The observed decreased tuberculin sensitivity in atopic individuals is, however, probably not the cause, but rather the consequence of the disturbed immune regulation in atopic diseases.