Immunological Characteristics and Skin Structure of the Meishan Pig: Serum Complement Activity, Serum C3 Level and Immune Response

We examined several immunological characteristics of Meishan pigs to determine the cause of their high susceptibility to skin disease. The total serum complement activity (CH 50) and the third complement component (C3) levels of Meishan pigs were, respectively, two-fold and 1.2-1.3 fold those of the levels of the European pig breeds at 26 weeks of age. We compared changes in total serum immunoglobulin G (IgG) levels in Meishan and Duroc pig breeds after Alum-BSA immunization. The IgG levels of the immunized Meishan pigs at 16 weeks of age were remarkably higher than those of the Duroc and non-immunized control Meishan pigs (2.9-fold and 2.6-fold, respectively). Meishan pigs were also found to have different SLA class II genotypes, thicker epidermises, and clearer increases in eosinophil infiltration with age than their Duroc counterparts. Furthermore, a severe eosinophil infiltration was found around blood capillaries in the dermis and hypodermis of Meishan pigs at 153 days of age. These histopathological findings appear to reflect characteristics of the allergic dermatitis. Collectively, these results suggest that the Meishan pig has a high tendency toward type I allergic reaction, a tendency which may be due to the breed's high CH 50 and C 3 levels and high humoral immune responsiveness.