Antigen-specific antibodies
The titer of the serum anti-OVA IgG Abs was increased in the groups treated with Morus alba L. and OVA or CT compared to the OVA-only treated group (Fig. 3). A comparable immune response was produced when an antigen mixed with CT was used as a positive control. To determine the immunoglobulin patterns induced by oral Morus alba L. administration, OVA-specific serum IgG1 and IgG2a anti-OVA Abs were measured. The oral immunization of OVA and CT induced a predominantly antigen-specific IgG1 response, with little IgG2a. Co-administration of OVA with Morus alba L. increased the levels of both the IgG1 and IgG2a Abs two-fold (Fig. 3 C, D). No change in the IgE content was observed. CT induced the secretion of IgE Abs two-fold compared to OVA (Fig. 3E).
We further determined whether oral tolerance affected the mucosal Ab responses in serum, saliva, and the intestine. The oral immunization of OVA plus CT as an adjuvant elicited significant antigen-specific mucosal IgA Ab responses. The serum and intestinal responses were significantly increased in the Morus alba L. or CT combination groups compared to the OVA group (Fig. 3 F, H). There was no effect on salivary IgA responses (Fig. 3G).