Japanese and U.S. researchers say allergy shots for pregnant women may protect babies for life

by Magdalena Osumi

Staff Writer

A group of researchers based in Japan and the United States believe that administering allergy shots to women during pregnancy could prevent their unborn children from developing allergies after birth and throughout their lives.

The researchers believe the special shots, which prevent offspring from producing specific antibodies that trigger allergic reactions, could effectively halt the development of human allergies including atopic dermatitis, asthma, pollen and food allergies. The teams hope the treatment could be commercialized within five to 10 years.

The scientists, who come from Japan’s National Center for Child Health and Development, Tokyo’s Jikei University School of Medicine and the California-based La Jolla Institute for Allergy and Immunology, have performed related experiments on mice.

“We discovered that preventing infant (mice) from creating antibodies would effectively diminish the risk of allergies in their adult lives,” said Hirohisa Saito, deputy director at the National Center for Child Health and Development, who is one of the leaders in the research.

In a phone conversation on Tuesday, Saito, an expert in immunology and cell biology, explained that allergies occur when people develop antibodies called immunoglobulin E (IgE), which combine with allergens and trigger allergic reactions.

Saito said that depending on the environments to which infants are exposed, they may produce such antibodies within the first three or four months after birth.

“Researchers agree that fighting them within that period is critical,” said Saito. “Once they appear in our immune system, it’s impossible to cure allergies.”

Saito explained that injecting allergy shots during pregnancy can effectively kill so-called mast cells, which release chemicals that interact with allergens and cause allergic reactions. Since adults already have a large number of IgE antibodies in their immune system, such shots would not be effective for them, he said.

According to the health ministry, about half of the population of Japan struggle with some kind of allergy. The nation has also seen a rise in the incidence of hay fever.

By injecting shots that counteracted IgE and killed the mast cells in pregnant mice, the researchers succeeded in preventing IgE antibodies from developing for six weeks. According to Saito, that would be comparable to a period of around five months in humans.

Saito said that anti-IgE medicine injected into expectant mothers could immunize unborn babies and would be effective in preventing all kinds of allergies.

“Such medicine has already been used to ease symptoms of asthma in pregnant women and has been proven safe for the fetus,” said Saito. “Injecting it into the mother could have the same effect as injecting it directly into the child.”

Referring to rising calls for caution over giving allergy shots to newborn babies, Saito said the latest research would alleviate those public worries as the shots would be administered to the mother during pregnancy. No side effects have been reported so far, according to the researchers.

Saito and the late Kimishige Ishizaka, the immunologist who in 1966 discovered IgE antibodies, are the architects for the two-year project, which launched in 2016. Ishizaka passed away in July.

The results of the study have been published in the November issue of “The Journal of Allergy and Clinical Immunology,” a monthly U.S. medical journal.