HUMAN T-CELL AND B-CELL IMMUNE-RESPONSES TO FEL-D-1 IN CAT-ALLERGIC AND NON-CAT-ALLERGIC SUBJECTS

Background In allergic individuals exposure to allergen leads to the i nduction of allergen-specific IgE which, upon binding to its high affi nity receptors on mast cells and basophils, primes these cells for deg ranulation. This degranulation, a result of specific IgE/allergen-inte raction, initiates the debilitating symptoms of allergy and the potent ially life-threatening symptoms of anaphylaxis. The lack of symptoms f ollowing antigen encounter by non-allergic individuals is probably due to the undetectable levels of allergen-specific IgE in the plasma of non-allergic individuals. Objective To compare the immune responses of allergic and non-allergic individuals. Method We compared the immune responses of 42 cat-allergic subjects with 16 non-cat-allergic subject s to the major cat allergen, Fel d 1. We have measured plasma immunogl obulin levels and the proliferative responses of fel d 1 primed T cell lines to Fel d 1 peptides. Results While these two groups have simila r levels of Fel d 1 specific IgG, only subjects in the cat-allergic gr oup have detectable Fel d 1 specific IEE, Affinity purified Fel d 1 wa s used to generate T cell lines from peripheral blood mononuclear cell s of these same subjects. The proliferative responses of these T cell lines to intact Fel d 1 and a set of overlapping peptides covering the entire sequence of the molecule demonstrated that the pattern of epit ope recognition was similar in both groups. Conclusion Our data sugges t that factors other than T cell recognition of specific epitopes are responsible for the nature of allergic immune responses generated when allergen is encountered.