Breast milk may stimulate immunity.

Breast milk may stimulate immunity

Scientist have long recognized that breast milk contains maternal antibodies that help newborn mammals, including human babies, to fight infection. Now researchers are finding evidence that one or more proteins in breast milk may also stimulate babies' own immune systems. The as-yet-unidentified protein or proteins speed the maturation of cultured B lymphocytes (a type of white blood cell) and prime them for production of antibodies, says Michael H. Julius of McGill University in Montreal.

Maternally acquired antibodies are very useful to the newborn, whose immune system is not fully developed, Julius said in an interview. "But at some point in time we have to get the baby's immune system off the ground. These proteins may be important in helping the newborn to cope with antigens in the outside world."

As reported in the March 1 JOURNAL OF IMMUNOLOGY, Julius first noticed that sheep colostrum -- the milk produced immediately after the birth of a lamb -- enhances the growth and differentiation of cultured white blood cells. Since then, he says, he has seen similar activity in human milk.

Armond S. Goldman of the University of Texas Medical Branch in Galveston told SCIENCE NEWS that other studies, including some of his own, have suggested the presence of immunity enhancers in human breast milk. In research to be published in the May PEDIATRIC RESEARCH, Goldman finds that certain soluble proteins in breast milk can activate macrophages -- white blood cells that complement B lymphocytes in the immune response. "We're busily trying to characterize that material," he says.

Julius says that his earlier experiments looked at the effects of human-and sheep-milk proteins on cultured mouse B lymphocytes, but that current work using human-milk proteins and human cells is showing similar results. -R. Weiss