In a follow-up study of children with immediate anaphylactic reactions to cows milk as infants, a prolonged pattern of hypersensitivity was noted with the development of multiple food and inhalant allergies, multiple hospitalizations and frequent episodes of drug reactions. These children may continue to manifest hypersensitivity and grow into adults with immune-mediated diseases. Although there are few studies which focus on milk-induced disease if adults, there is enough suggestive evidence to suspect that milk proteins play a major role in human disease at all ages. There are at least 30 antigenic primary proteins in milk. Digestion probably increases the number of possible antigens to over 100.
Milk proteins tend to stay intact as milk is converted to dairy products of all types.
While lactose intolerance may not be an issue with yogurt ingestion, for example, milk protein allergy remains. Digested fractions of each of the milk proteins may induce the production of IgE, IgA, and IgG antibodies and may trigger complex, variable immune responses. Skin tests with whole milk proteins are, therefore, misleading - type 1 responses do appear regularly on skin tests showing IgE activity against intact proteins, but secondary antigens are not detected. Furthermore, milk antigens tend to get through the GIT mucosa intact and are therefore responsible for a host of delayed immune responses which do not depend on IgE and do not show up on skin tests. The role of milk proteins in triggering the most serious pathology usually goes undetected.