We studied 20 infants of mothers with
IDDM participating in a pilot study for a dietary intervention trial, testing the hypothesis that avoidance of cow's milk
proteins early in life will reduce the risk of subsequent
IDDM. The aim was to evaluate the elimination of
IDDM-associated
antibodies from the peripheral circulation of the infants, the possible emergence of
autoantibodies indicating beta-cell destruction, and the influence of the dietary intervention and
genetic disease susceptibility on the development of these
autoantibodies. Transplacentally transferred islet cell
antibodies (ICAs) and
antibodies to the 65-kDa
isoform of
glutamic acid decarboxylase (GAD65As) disappeared from the peripheral circulation of most infants over the first few months of life and in all infants before the age of 9 months.
Insulin antibodies were eliminated before the same age in all cases but one. The higher the initial antibody level was, the longer the time required for elimination. Four infants tested positive for
insulin autoantibodies (IAAs) on at least one occasion during the first year of life, and 5 out of 16 unaffected subjects (31%) had IAAs at the age of 2 years. One infant became positive for IAA before the age of 6 months, with increasing levels later, seroconverted to positivity for ICAs and GAD65As between 6 and 9 months and presented with clinical
IDDM at the age of 14 months. He had the
HLA DQB1*0302/x genotype, which predisposes carriers to
IDDM, and had been given the
casein hydrolysate formula as supplementary milk. There were no significant differences in the levels of various
autoantibodies between two groups of subjects defined either on the type of dietary intervention or the degree of
genetic susceptibility. The findings indicate that transplacentally transferred
antibodies related to
IDDM are usually eliminated from the peripheral circulation of infants before 9 months of age and that
IDDM-associated
autoantibodies may emerge before the age of 6 months. Our results also illustrate that avoidance of cow's milk
proteins over the first 9 months of life does not provide total protection against
IDDM.