While a lot is known about the nature of the sensitising antigen, there has been little study of immune cells within the intestine that may be generated by the presence of a potential food allergen. The aim of this study was to examine the role of the mucosal immune system in cow's milk allergy.

The technique of flow cytometry was used to examine the immune response of proinflammatory lymphocytes (that cause the allergic response) and the regulatory lymphocytes (that regulate the allergic response) from children with or without food allergies before and after challenge with cow's milk protein.

The results indicated that the major difference in children with food allergy was the deficiency of a regulatory lymphocyte population, rather than the excess of proinflammatory cells. This regulatory population, called T_H3 cells, produce a cytokine (TGF-beta) which inhibits the activation of all other cells in the locality. The researchers were able to confirm this finding using the techniques of immunohistochemistry (which identifies the protein) and in situ hybridisation (which identifies the genetic material involved in synthesising the protein).

The researchers concluded that the reduced production of the regulatory cells might result in failure to establish immune tolerance within the intestine, allowing any potentially food-reactive lymphocyte to respond unchecked. They have not established a direct mechanism for generation of these cells, and suggest that further work will be needed for this.