LJI researchers in the labs of Alessandro Sette, Ph.D., and Bjoern Peters, Ph.D., are assessing whether standard immunotherapies could be modified to minimize hypersensitivity. To do so, they are dissecting cellular responses to discrete components of Timothy grass extracts by analyzing immune cells in blood samples from patients inoculated with Timothy grass extracts. Previously, scientists knew that exposure to the entire extract stimulated B cells to produce an allergen-specific antibody called IgE, kicking off a cell- signaling cascade promoting an adverse allergic response.
The team has identified discrete protein fragments, or peptides, contained in Timothy grass extracts that activate an allergic response by stimulating T helper cells called Th2 cells without prompting B cells to generate high levels of IgE. Furthermore, these inflammatory Th2 responses appear to decrease with repeated immunotherapy, most significantly in patients who also report alleviation of symptoms.
This is a very positive sign, as an overly enthusiastic Th2 cell response underlies development of allergy and asthma in numerous contexts. Sette and Peters are now asking whether immunotherapy with purified peptide cockroach allergens, which has not yet been attempted, might be more effective in maintaining a healthy ratio of Th1 to Th2 cells. Such an approach could also be safer, as it should not elicit IgE-related side-effects associated with anaphylactic shock.