Allergy is due to human body's hyperimmune response. Boosting immunity hence does not make sense. There are desensitization treatments where an allergen is given in slowly increasing concentrations so as to make the body tolerant to the allergen. Before you undergo these treatments, you need a skin prick test done to find out the substances you are allergic to. If the polyps are large and block the sinus openings, then it is better to undergo surgery and control the allergic response later using nasal sprays. Small polyps can be easily controlled by antiallergic sprays and tablets.