The immunoglobulin system of the suckling pig.

Pig immunoglobulins The pig immunoglobulin system has now been well characterized and has been the subject of two recent reviews (Bourne, 1971a; Porter & Allen, 1972). Three immunoglobulin classes are recognized which on the basis of their physicochemical properties and antigenic relationships may be regarded as analogous to human IgG, IgM and IgA. Some of the properties of pig immunoglobulins are shown in Table I (Bourne, 1971~). Immunoglobulin IgG is quantitatively the most important in pig serum and colostrum; two main sub-classes exist-IgG, and IgG,. Both sub-classes have a sedimentation coefficient (s) of 7. Immunoglobulin IgM occurs as a macroglobulin and, like the corresponding immunoglobulin in other species, possesses an s value of 19 s. The pig IgA system has been shown to be similar to that present in other species and it has been suggested that the main biological role of IgA is associated with local defence of mucosal surfaces (Tomasi, 1967).