ALLERGY AND AGE
If defective genes lead to allergy then one would expect most allergies to begin early in life, as indeed they do. Symptoms cannot be produced the first time a person is exposed to an allergen, however. Although the body already has the capacity to produce antibody to the allergen concerned (in the form of as-yet-unactivated B cells) the antibody itself is not there. An initial exposure is required to enable the body to ‘find’ the right B cell from its extensive stock and multiply it up to useful levels. Once this has happened, a second exposure to the allergen can stimulate antibody (IgE) production. The allergen can then trigger off IgE-coated mast cells with devastating results.
Despite this, a baby may react to a food allergen the first time he eats it because molecules of the food may have reached him by other means. One such route is breast milk, which contains molecules from the foods the mother herself is eating – only a few, of course, but enough to sensitize a highly atopic baby. Some babies may even be sensitized before birth, by food molecules in the mother’s blood that pass into the foetus’s blood. So it is important for atopic mothers-to-be to think about their diet. Chapter Thirteen suggests practical steps that can be taken by parents to reduce the risk of sensitizing their children.
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Tags: Allergies