Food and food additives in severe atopic dermatitis

In this study the role of food additives, tyramine and acetylsalicylic acid, was investigated by double-blind placebo-controlled challenges (DBPCC) in 25 children with severe atopic dermatitis (AD). All children challenged with foods (n = 24), except one, showed one or more positive reactions to the DBPCC with foods. Positive reactions presented as different combinations of flares of skin symptoms, intestinal symptoms and respiratory symptoms. Seventeen children (70.8%) showed a positive challenge to egg, 12 to wheat (50%), eight to milk (33.3%) and eight to soya (33.3%). Six children underwent DBPCC with food additives, tyramine and acetylsalicylic acid. All were found to demonstrate positive skin and/or intestinal reactions to at least one of the food additives. Two children reacted to tartrazine, three to sodium benzoate, two to sodium glutamate, two to sodium metabisulfite, four to acetylsalicylic acid and one to tyramine. It is concluded that some foods, food additives, tyramine and acetylsalicylic acid, can cause positive DBPCC in children with severe AD.     

Frequency and intensity of late asthmatic reactions after bronchial allergen challenge in asthma and rhinitis

The occurrence of late asthmatic reactions after bronchial allergen challenge was studied in 50 house dust mite allergic patients subdivided in three groups: one group had asthma without nasal symptoms, another group had rhinitis without pulmonary symptoms and a third group had a combination of both asthma and rhinitis. Late asthmatic reactions were present in 80% of asthmatic patients and in 18.7% of rhinitis patients. The degree of non-specific bronchial reactivity to histamine (provocative dose 15 or PD15 histamine) and the degree of immediate reactivity to allergen (PD15 house dust mite) did not differ significantly between patients with and without late asthmatic reactions. These findings suggest that an important difference between asthma and rhinitis is the lack of late asthmatic reactions in rhinitis patients, whereas the degree of immediate bronchial reactivity to the allergen is similar in asthma and rhinitis.     

Suppression of the late asthmatic reaction by hyposensitization in asthmatic children allergic to house dust mite (Dermatophagoides pteronyssinus)

In this study, we wanted to test the hypothesis that hyposensitization (HS) abrogates the late asthmatic reaction (LAR). We therefore selected 15 asthmatic children (subjects) sensitized to house dust mite (HDM), as proven by positive prick tests and/or specific IgE via the RAST. All children demonstrated a positive bronchial provocation test (BPT) to HDM; 14 showed a dual asthmatic reaction and one child showed an isolated LAR. All children were treated with anti-asthmatic drugs and received HS. They were rechallenged after 1 yr of HS while their anti-asthmatic medication was not changed, except for beta-agonists which were used only for relief of symptoms. Two BPTs, with a mean interval of 6.4 months, were also performed in eight asthmatic children (controls), who did not receive HS. In the controls, the same reaction pattern was observed during both BPTs. In the subjects, the LAR completely resolved in 5/15 after 1 yr of HS (P = 0.04). Furthermore, as a group, the subjects showed a less severe LAR after 1 yr of HS (expressed as mean fall of FEV1) (P less than 0.0001). The PD20 of the immediate asthmatic reaction (IAR) was the same as before HS was started, but the IAR was also less severe after 1 yr of HS (expressed as mean fall of FEV1) (P = 0.028). From these observations it is concluded that, in asthmatic children, HS may resolve and/or reduce the severity of the LAR. Although the PD20 of the IAR is not changed, the severity of the IAR is also reduced after 1 yr of HS.     

Lymphocyte transformation test with house dust mite (Dermatophagoides pteronyssinus) in normal children, asthmatic children and asthmatic children receiving hyposensitization

In the first part of this study the proliferative response of lymphocytes (lymphocyte transformation test) to house dust mite (HDM) stimulation in cultures was studied in normal children (n= 16), asthmatic children who never received hyposensitization (HS) (n = 50) and asthmatic children receiving HS with HDM for at least 6 months (n = 20). The results are expressed as disintegrations per minute (d.p.m.) and as stimulation index (SI = d.p.m. in the presence of the allergen/d.p.m. in the control culture). A positive SI (> 2) was found in 54% of the asthmatic children who never received HS, in 30% of the asthmatics receiving HS and in none of the normal children. Furthermore, between asthmatics with and without HS, the SI was not statistically different, although asthmatics without HS tended to have a higher SI (median value: 2.13 vs 1.38) (P= 0.10). In a second series of experiments the effect of adding interleukin-2 (IL-2) to the lymphocyte cell culture was studied in asthmatic children with and without HS. Interleukin-2 induced an additional stimulatory effect on the lymphoproliferative response to HDM and to phytohaemagglutinin in patients who never received HS, but had no effect in patients receiving HS. We conclude that HS treatment seems to have an inhibiting effect upon this proliferative response, not only inhibiting the degree of the allergen-induced lymphocyte proliferation, but also inhibiting the sensitivity of proliferating lymphocytes for IL-2. These inhibiting effects upon lymphocytic activation could be responsible for the anti-inflammatory effects (i.e. suppression of the late asthmatic reaction) of HS.