Iron and iron/manganese ratio in forage from Icelandic sheep farms: relation to scrapie.

This study was undertaken in order to examine whether any connection existed between the amounts of iron in forage and the sporadic occurrence of scrapie observed in certain parts of Iceland. As iron and manganese are considered antagonistic in plants, calculation of the Fe/Mn ratios was also included by using results from Mn determination earlier performed in the same samples. Forage samples (n = 170) from the summer harvests of 2001-2003, were collected from 47 farms for iron and manganese analysis. The farms were divided into four categories: 1. Scrapie-free farms in scrapie-free areas (n = 9); 2. Scrapie-free farms in scrapie-afflicted areas (n = 17); 3. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 4. Scrapie-afflicted farms (n = 9). Farms in categories 1 and 2 are collectively referred to as scrapie-free farms. The mean iron concentration in forage samples from scrapie-afflicted farms was significantly higher than in forage samples from farms in the other scrapie categories (P = 0.001). The mean Fe/Mn ratio in forage from scrapie-afflicted farms was significantly higher than in forage from scrapie-free and scrapie-prone farms (P < 0.001). The results indicated relative dominance of iron over manganese in forage from scrapie-afflicted farms as compared to farms in the other categories. Thus thorough knowledge of iron, along with manganese, in soil and vegetation on sheep farms could be a pivot in studies on sporadic scrapie.

Cord blood IgE levels are influenced by gestational age but do not predict allergic manifestations in infants.

The predictive value of cord blood IgE (cIgE) for atopy and related disorders was investigated. Samples were collected from 792 infants delivered consecutively at the National University Hospital in Reykjavík in 1987. The concentration of IgE, but not that of IgA, was found to increase with increasing gestational age at birth. There was no correlation between IgE and IgA levels in individual samples. At the age of 18-23 months 180 of these children were studied for manifestations of allergy and related disorders. Included were all available infants with detectable (> or = 0.23 kU/L) cIgE. However, infants born by Cesarean section or with IgA exceeding 10 mg/L were excluded because of potential contamination with maternal blood. The clinical evaluation was made without knowledge of the IgE levels. Sixty-six of the 180 participants (36.6%) were judged to have had definite allergic manifestations. However, no striking correlation was found between allergic symptoms and cIgE levels in this study, nor did high levels of IgE add significantly to the predictive value of family history. Children with atopic features had more frequently been affected by otitis media. Unexpectedly, infants with intermediate cIgE levels (0.2-0.6 kU/L) were significantly less affected by otitis media than children with unmeasurable (< 0.2 kU/L) or high (> or = 0.7 kU/L) cIgE levels. It is concluded that cord blood IgE can not be used to predict allergic manifestations in children under the age of 2 years.

Correlation between serum immunoglobulin A concentrations and allergic manifestations in infants.

We studied the relationship of serum levels of IgA and IgE to allergic manifestations and otitis media in a cohort of 179 Icelandic children, aged 18 to 23 months. Only one of the infants had IgA deficiency (less than 50 micrograms/ml); all the others had IgA levels that were normal for their age. The children were divided into three groups according to their IgA levels (lowest 25%, intermediate 50%, highest 25%) and the clinical findings analyzed accordingly. The cumulative incidence of definite allergic manifestations was 37%. Asthma and otitis media were significantly more common among the infants with low normal IgA levels than among those with intermediate to high IgA levels. There was also a significant association between the severity of allergic manifestations and low IgA levels (p = 0.002). Children with detectable IgE (greater than or equal to 0.23 kilounit/L) had a higher incidence of atopic manifestations than did children in whom IgE was not detectable, but only a weak correlation was found between the occurrence and extent of allergic symptoms and increasing amounts of IgE beyond the 0.23 kilounit/L level. These findings suggest that atopic manifestations in infants may be more dependent on delayed maturation of IgA production than on overproduction of IgE.