Study of immunisation regimes for the stimulation of local immunity in the pig intestine.

Experiments are described which demonstrate that intraperitoneal injection of a soluble protein antigen (ovalbumin) in Freund's complete adjuvant (FCA) followed 14 days later by seven days of repeated infusions of an ovalbumin/DEAE-dextran mixture resulted in the appearance of IgA-specific antiovalbumin-containing cells (AOCC) in the intestinal lamina propria and IgA associated specific antibody in intestinal secretion of pigs. Neither intraperitoneal injection alone nor infusion of the antigen mixture alone resulted in a significant local intestinal immune response. In intraperitoneal primed animals the repeated infusion of ovalbumin without DEAE-dextran or a single intraduodenal injection of ovalbumin both resulted in a similar AOCC response in the intestine but, in the absence of DEAE-dextran, IgA was not the predominant class specificity of AOCC. Evidence is also presented for a depression of the intestinal immune response when intraperitoneal immunisation was performed using a large dose of antigen in FCA.