Abrogation of oral tolerance by feeding encapsulated antigen.

Results from previous studies have indicated that suppression of immune responses cannot be abrogated once oral tolerance has been established. Using a new methodology, OVA was encapsulated and fed to tolerized BDF1 mice. Results from these studies indicated that although IgG2a titers remained low, total IgG and IgG1 antibody titers were no longer suppressed compared to controls. Furthermore, in vitro splenocyte proliferation was not significantly suppressed in tolerized mice fed encapsulated OVA. To determine whether oral tolerance could be abrogated in other strains of mice, BALB/c mice were tolerized and fed encapsulated OVA. Results from these studies indicated that IgG2a as well as IgG1 and total anti-OVA antibody titers were no longer suppressed. Although splenocyte proliferation did remain significantly suppressed in these mice, IFN-gamma and IL-4 levels were no longer decreased. To the best of our knowledge, this is the first time that abrogation of an established oral tolerance has been demonstrated.

Oral immunization with a Streptococcal pneumoniae polysaccharide conjugate vaccine in enterocoated microparticles induces serum antibodies against type specific polysaccharides.

The authors examined the antibody responses of mice orally immunized with pneumococcal polysaccharide (type 23F) or a pneumococcal polysaccharide conjugated to the outer membrane protein complex of Neisseria meningitides (23F-OMPC). These antigens were administered either in solution or entrapped within microcapsules. Only the mice receiving the encapsulated conjugate vaccine produced significant levels of anti-polysaccharide serum antibodies. These responses, observed after a second oral immunization with the conjugate, were predominantly IgG. Thus, the conversion from a T-cell-independent to a T-cell dependent response, achieved through conjugation was maintained following oral delivery. However, no local secretory IgA anti-polysaccharide response was detected in these mice indicating that while the OMPC carrier augments orally induced IgG responses, it was insufficient for the induction of secretory IgA.

Activation patterns of murine B cells after oral administration of an encapsulated soluble antigen.

Oral administration of soluble protein antigen, ovalbumin (OVA), encapsulated by an acid-resistant acrylic polymer, induced a strong immune response in BDF1 mice. Mice fed the encapsulated OVA showed activation of antigen-specific IgA, IgG and IgG1 isotype antibody-secreting cells which migrated to various lymphoid tissues via the common mucosal immune system traffic pathway. The highest number of antigen-specific antibody secreting cells was found in the Peyer's patches isolated from the upper segment of the small intestine, with their numbers declining along the length of the intestinal tract. Oral administration of this product suggests activation of lymphocytes exhibiting Th2 phenotype as shown by OVA-specific IgA and IgG1 isotype antibody responses. In conclusion, we demonstrated that oral administration of encapsulated soluble protein, in the absence of adjuvant, can activate the murine common mucosal immune system.

Activation patterns of murine B cells after oral administration of an encapsulated soluble antigen.

Oral administration of soluble protein antigen, ovalbumin (OVA), encapsulated by an acid-resistant acrylic polymer, induced a strong immune response in BDF1 mice. Mice fed the encapsulated OVA showed activation of antigen-specific IgA, IgG and IgG1 isotype antibody-secreting cells which migrated to various lymphoid tissues via the common mucosal immune system traffic pathway. The highest number of antigen-specific antibody secreting cells was found in the Peyer's patches isolated from the upper segment of the small intestine, with their numbers declining along the length of the intestinal tract. Oral administration of this product suggests activation of lymphocytes exhibiting Th2 phenotype as shown by OVA-specific IgA and IgG1 isotype antibody responses. In conclusion, we demonstrated that oral administration of encapsulated soluble protein, in the absence of adjuvant, can activate the murine common mucosal immune system.

Association of restriction fragment length polymorphisms of swine leucocyte antigen class I genes with production traits of Duroc and Hampshire boars.

Restriction fragment length polymorphism analyses of swine leucocyte antigen (SLA) class I genes were performed on 70 Duroc and 38 Hampshire boars from the 1986-87 national performance tests of each breed in the USA. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA, isolated from white blood cells, using PvuII endonuclease and a swine major histocompatibility complex (MHC) class I probe. Durocs had an average of 11 restriction fragments, with the most common being in 63% of the boars and the least common appearing in only one boar. Hampshire boars had an average of 12 restriction fragments, with the most common appearing in 73% of the boars and the least common appearing in only one boar. Least squares procedures and stepwise regression methods were used to examine the association between DNA restriction fragments and the selection index (INDEX), average daily gain (ADG), average backfat thickness (BF), loin muscle area (LEA), and age at 104 kg (DAY104). In the Duroc breed one DNA restriction fragment was associated with decreased INDEX (P less than 0.05) and decreased ADG (P less than 0.05) whereas two other fragments were associated with increased BF (P less than 0.05). In the Hampshire breed two restriction fragments were associated with an increase in INDEX (P less than 0.05). Cluster analyses were used to group pigs of each breed on the basis of similar RFLP patterns. One cluster group in the Duroc breed was associated with lower average INDEX values (P less than 0.05), greater average DAY104 (P less than 0.05), and a larger mean LEA (P less than 0.05). In the Hampshire breed one cluster group was associated with lower INDEX (P less than 0.05). These results suggest there may be an association between swine MHC class I genes and performance traits in swine. The use of SLA class I restriction fragments, as genetic markers, may have potential in the future for improving pig performance.

Genetic variability between two breeds based on restriction fragment length polymorphisms (RFLPs) of major histocompatibility complex class I genes in the pig.

Restriction fragment length polymorphism analyses of SLA class I genes were performed on 55 Duroc and 24 Hampshire boars from the 1986-87 national performance tests of each breed. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA isolated from white blood cells by using Pvu II, Bam HI, and Eco RI endonucleases and a swine MHC class I probe. Genetic variability within and between the two breeds was estimated in terms of nucleotide diversity, by using a mathematical analysis based on the different RFLP patterns. The nucleotide diversity calculated within each breed was less than that between the two breeds. The results from the nucleotide diversity analysis suggested that genetic variability was greater in the Duroc breed than in the Hampshire breed. A relatively high level of genetic variability was shown in the class I major histocompatibility complex genes in the pig.