Variability of the immunological state of germfree colostrum-deprived Minnesota miniature piglets.

Minnesota miniature piglets obtained by hysterectomy and deprived of colostrum were examined for the presence of immunoglobulin by immunoelectrophoresis, double-gel diffusion, and radial immunodiffusion techniques with specific anti-immunoglobulin chain sera. A large amount of variability existed between different litters of piglets and between different piglets within the same litter, ranging from no detectable immunoglobulin in the serum to very high immunoglobulin levels approaching that of the adult pig. All known classes of porcine immunoglobulin including immunoglobulin G, immunoglobulin M, and immunoglobulin A could be found in the sera from litters where there was extensive placental damage. This contaminating immunoglobulin was shown to have antibody activity to actinophage MSP-2 even when present in very low concentrations. The low level contamination with immunoglobulin G, which was the most frequently encountered type of contaminant, was demonstrated to be similar to sow immunoglobulin G both antigenically and in its molecular size. The data demonstrates that individual piglets must be tested for immunoglobulin content rather than being assumed to be immunologically "virgin" and emphasizes the need for an intact placenta barrier to obtain piglets free from maternal immunoglobulin and devoid of antigenic stimulation.