Immunochemistry of food antigens.

The complex mixture of molecules called food contains many types of molecules, some of which cause allergic or pseudo-allergic reactions in some humans. The identification of the antigenic molecules in the various foods and the type of allergic reaction they elicit is important for the satisfactory diagnosis in the individual patient and in the control of modified foods. The study of food antigens by crossed immunoelectrophoresis allows investigations of individual antigens without the interference of other antigens which are present simultaneously. We studied cow's milk electrophoresed into anti-bovine whey and anti-bovine casein. A number of precipitates are described, including albumin, alpha-lactalbumin, beta-lactoglobulin and immunoglobulin. The compositions of different infant milk formulae are compared with cow's milk heated under varying conditions. Albumin and immunoglobulins are the most labile components while beta-lactoglobulin is able to withstand even proteolysis by pepsin for some time. The antigenicity of these proteins in humans is shown by the presence of precipitating antibodies and specific IgE in human sera. Data from hen's egg white and wheat flour are reviewed in the same light. As an example of a reaction that is very difficult to differentiate from an immune reaction, the possible role of lectins is discussed.