(Agencies)
Updated: 2008-01-29 07:34

NEW YORK - Lactating mice that develop tolerance after exposure to airborne antigens appear to be able to transfer this immunity to their offspring though breast-milk.

The tolerance was transmitted to the newborn mice through breast milk and antigen-stimulated allergic asthma was prevented, a French research team reports in the advance online edition of Nature Medicine. Antigens are substances the body recognizes as foreign that trigger the immune system to mount a defensive reaction, which accounts for allergy symptoms.

Dr. Valerie Julia, at Universite de Nice-Sophia-Antipolis in Valbonne, and associates exposed lactating mice to ovalbumin aerosols every other day until their offspring were weaned. (Ovalbumin is the major protein in the white part of an egg.)

Examination of breast milk obtained from the stomachs of the young mice showed evidence that the airborne ovalbumin was transferred from the mother to the newborn through the milk.

On reaching adulthood (6 to 8 weeks old), the offspring, as well as offspring of mice not exposed to ovalbumin, were given abdominal injections of ovalbumin. They then were exposed to daily ovalbumin aerosols for 5 days in a row.

Airway hyperreactivity, which occurs with allergic asthma, was reduced in the mice that were breast-fed by ovalbumin-exposed mothers. Fluid samples taken from the throat contained reduced numbers of eosinophils, a type of white blood cell usually produced during allergic reactions. Examination of the tissue of the mice revealed mild cellular infiltration and decreased mucus deposition in the airways.

The other group of mice showed no signs of protection from allergic asthma.

These results and those of other studies "may pave the way for the design of new strategies to prevent the development of allergic diseases," the researchers conclude.