Correlation between atopic diseases and tuberculin responses

In recent decades, the prevalence of atopic diseases has risen steadily in developed countries. The reasons for this increase are not clear. It has been hypothesized that a reduction in infections and immunization programs may contribute to the increase in the prevalence of atopic diseases. We investigated the relationship between tuberculin response and atopic disease.

A total of 538 (73.0%) atopic and 198 (27.0%) nonatopic children vaccinated with BCG were included in the study. All the children included in the study had neither been given BCG nor tuberculin skin-tested in the previous 6 months, nor did they have a condition known to cause anergy. All the children were given five tuberculin units PPD, and PPD indurations were recorded after 48 h.

The PPD induration size was 6.8 +/- 5.6 mm (mean +/- SD) in atopic children and 7.4 +/- 5.9 mm in nonatopic children. The difference between the two groups was not significant (P > 0.05). The PPD induration sizes of children with asthma, rhinitis, and atopic dermatitis were found to be similar. The children with atopic dermatitis had lower PPD induration size, but this was not statistically significant (P> 0.05). The rates of negative (< 5 mm skin induration) and intermediate (5-9 mm) responses were 32.6% and 30.5% in atopic children and 30.2% and 32.4% in nonatopic children, respectively. Positive tuberculin responses (PPD > 10 mm) were recorded in 36.9% of atopic children and 37.4% of nonatopic children. Total serum IgE levels of atopic and nonatopic children were 623.35 and 46.78 IU/ml, respectively. There was no correlation between serum total IgE level and PPD induration size (r = - 0.0012, P = 0.737).

We did not find any relationship between tuberculin response and atopy status later in life in BCG-immunized subjects. We need further studies to clarify the effect of BCG on the development of atopy.