Immune response of the hamster to oral and parenteral immunization

Maternal antibodies block induction of oral tolerance in newly hatched chicks

Oral antigens administered to newly hatched chicks induce oral tolerance. Some of the antigens encountered via the gut during this period are pathogen-derived, and should not be tolerogenic. As chicks are protected in early life by maternal antibodies, we assumed that the same antibodies also served to prevent tolerance by blocking the relevant antigen. We used bovine serum albumin (BSA) as a model antigen, and initially showed that tolerance was invariably generated in chicks younger than 3 days of age. We then showed that tolerance and its prevention were due to circulatory BSA: intravenous BSA induced tolerance, BSA was present in serum of previously fed chicks, and tolerance was completely blocked in chicks containing high levels of maternal anti-BSA. These findings indicate that tolerance in the young chick is probably generated in central lymphoid organs, and that maternal antibodies block access of antigen to these organs, thereby preserving immune competence.

Response, tolerance and ignorance following oral exposure to a single dietary protein antigen in Gallus domesticus

The objective of this investigation was to analyze conditions leading to antibody responses against innocuous dietary protein antigens in the chick. The physical form of antigen was found to be important for immunization of mature chicks: bovine serum albumin (BSA) in solution was a powerful immunogen, while BSA powder was ignored. When BSA was fed to newly hatched chicks, either in solution or as powder, specific oral tolerance was induced. Tolerance increased with the dose of antigen fed, and was most effective in suppressing BSA-specific oral immunization. Hence, immune responses of mature chicks to innocuous dietary proteins are not likely to constitute a health hazard due to (a) prevalence of oral tolerance induced at hatch, and (b) availability of dietary proteins in solid form.

Antibody responses in the liver and bile of rats injected with horse erythrocytes

The intravenous injection of 1 ml of a 0.1% (or higher %) suspension of horse red blood cells (HRBC) into rats results in the appearance of high levels of agglutinating activity in bile as well as serum. Lower doses of HRBC induce reduced responses in both fluids, demonstrating that the biliary response is as dose-dependent as the serum response. The presence of IgM anti-HRBC antibody forming cells (AFC) in the liver in numbers equivalent to those detected in the spleen at day 6 of the study suggests them to be the most likely source of the biliary antibody. Also, the injection of HRBC into other parenteral sites (intramuscular [i.m.], intraperitoneal [i.p.] and intrathoracic cavity [i.t.]) results in a biliary response which is considered to originate from the IgM-, IgG- and IgA-anti-HRBC AFC detected in the liver, again in numbers approximating those detected in the spleen. Splenectomy of rats immunized i.p., i.m. and i.t. had only a minimal effect on the liver and biliary responses, indicating that AFC arising in peripheral lymphoid tissues can also relocate in liver. It is concluded that the liver is a major site of antibody synthesis following parenteral immunization leading to substantial levels of antibody being secreted into the gastrointestinal tract.

Lymphoid cells in chicken intestinal epithelium

The intraepithelial lymphoid cells of chicken small intestine were studied by light microscopy using 1 mu Epon sections, and by electron microscopy. Three cell types were found: small lymphocytes, large lymphoid cells, and granular cells. These cells correspond to the theliolymphocytes and globule leucocytes of previous authors. The numbers of all cell types increased with age. Correlation was found between the number of small lymphocytes and large lymphoid cells, but not between granular cells and either of the other two. A hypothesis is proposed, assigning these cells with a function in mucosal immunity.

Synthesis of immunoglobulins and 15 other proteins by diseased human kidneys

In an effort to determine the synthetic capacity of human kidneys for serum proteins, pieces of both kidneys removed at operation prior to transplantation were placed in organ culture. Incubation with 14C labelled amino acids and subsequent radioimmunoelectrophoresis with antisera to all five classes of immunoglobulins showed synthesis of IgG by all 5 pairs of kidneys of IgA and IgE by 4, and of IgM by 2. None synthesized IgD. Radioimmunoelectrophoresis with specific antisera to 15 non-immunoglobulin proteins revealed synthesis of lactoferrin and uromucoid while several other serum proteins, such as alpha1 antitrypsin and alpha2 macroglobulin, known for their binding properties, showed apparent synthesis. No evidence for secretory component synthesis was seen despite positive immunofluorescent localization in the tubular cells. Further, Zn alpha2 and beta2GP I also showed positive immunofluorescence but negative synthesis. It seems possible that these latter proteins may not be synthesized by the tubular cells but rather may be actively excreted or reabsorbed by them.

Comparative immunogenicity of heat-killed and living oral Salmonella vaccines

CD-1 mice were vaccinated intragastrically or intramuscularly with one or two doses of 200 mug of heat-killed Salmonella enteritidis 5694. Control mice were vaccinated with sublethal doses of living S. enteritidis Se795. The mice were challenged intragastrically with approximately 10(6)S. enteritidis 5694 SM(R) 7 to 14 days later, and the growth of the challenge population in the liver, spleen, mesenteric lymph nodes, lungs, and intestine was measured quantitatively. Mice receiving two doses of heat-killed vaccine by mouth were able to delay the systemic emergence of a gastrically introduced salmonella infection by 1 to 2 days. The corresponding liver and spleen populations were slightly lower than those seen in the normal controls. On the other hand, mice receiving the living, attenuated vaccine (either intravenously or intragastrically) developed an effective anti-salmonella immunity against subsequent reinfection.