Adjuvant-Free Murine Models of Allergic Sensitization to the Major Soybean Allergen Gly m 4

Gly m 4, a soybean PR-10 allergen, is known to trigger systemic allergic reactions. However, the intrinsic sensitizing potential of the allergen remains unclear. Adjuvant-free murine models of sensitization to Gly m 4 might help to investigate mechanisms of a soy allergy and establish relevant in vivo platforms for developing novel allergen-specific immunotherapy strategies. BALB/c mice were sensitized to Gly m 4 via intraperitoneal (i.p.), subcutaneous (s.c.), or intranasal (i.n.) routes, with or without adjuvant (alum or lipopolysaccharide (LPS)). In order to assess sensitization, we evaluated levels of allergen-specific IgE, IgG1, IgG2a, systemic anaphylaxis, rat basophil (RBL) degranulation, and cytokine/chemokine profiles in mouse sera. I.n. exposure with or without LPS proved to be ineffective and did not elicit sensitization. I.p. and s.c. routes of sensitization with and without alum induced a Th2-skewed response, which was demonstrated by high levels of IgE and IgG1, systemic anaphylaxis, and IgE-mediated degranulation of RBL cells. Adjuvant-free i.p. administration led to a shift in cytokine production, with reduced levels of proinflammatory (IL-1α/IL-6) cytokines and increased levels of Th2-associated (IL-13/GM-CSF) ones. Thus, adjuvant-free murine models validated the intrinsic sensitizing capacity of Gly m 4. Moreover, Gly m 4 demonstrated similar immunogenic profiles to Bet v 1 in alum-based models. It is the first evidence that soybean Gly m 4 can induce in vivo allergic sensitization in mice without adjuvants, particularly via i.p. and s.c. routes. Established adjuvant-free murine models offer a relevant tool for studying soy allergy and developing targeted immunotherapy.