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Age and Immune Response to Food Antigens
Dr. Lynn Averill, MD, PhD
Ahmed T, Sumazaki R, Nagai Y, Shibasaki M, Takita H. Immune response to food antigens: kinetics of food-specific antibodies in the normal population. Acta Paediatr Jpn. 1997 Jun;39(3):322-8. (Click here to view/order article at Pubmed) Dr. Averill:
Physicians should not measure IgG levels until patient at least 1-2 yrs of age as immune system is immature prior to this.
Titers of IgG antibodies to cow's milk and its component proteins revealed an age-related trend, peaking in the 5 months-1 year age group and then decreased to negligible values in adults.
The peak in the 5 months -1 year age group can be explained by a combination of factors:
1. increased consumption of cow's milk or milk formula in this group
2. higher intestinal permeability resulting in increased absorption of cow's milk proteins in the immunogenic form
3. absence of a fully developed mucosal secretory IgA system during this period of life. Intestinal secretory IgA forms immune complexes with food antigen in the gut inhibiting their absorption. It has been suggested that an immature secretory IgA system permits increased absorption of food antigen from the gut thereby increasing the possibility of systemic as well as local sensitization. Decline in titers with increasing age may be due to the development of systemic hypo-responsiveness which results from continuous antigenic stimulation.
The prevalences of IgG antibodies to cow's milk, its component proteins, and ovalbumin are influenced by age and feeding habits. Cross-reactivity to related food antigens is common. The presence of IgE antibodies to food antigens is not a physiological phenomeon.
The IgE antibody level is pre-determined while IgG can be prevented by eating habits, drug intake, environmental influences.Dr. Bennett:
Rationale for not testing children for IgG food allergies earlier than 1 year old.
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