SUMMARY The absorption of macromolecules from the small intestine of rats was studied in terms of the amount of peroxidase activity that appeared in thoracic duct lymph after a 10 mg dose of horseradish peroxidase had been injected directly into the lumen of the duodenum. When the horseradish peroxidase was injected as a solution in saline no peroxidase activity was detected in the lymph. When ethyl alcohol was included in the dose at final concentrations of 12.5-16% the flow rate of the lymph increased markedly for an hour or so and during this time peroxidase activity was detected in the lymph. An electronmicroscope study of the duodenal epithelium that had been exposed to alcoholic solutions of horseradish peroxidase showed that the enzyme had penetrated between the enterocytes. It was concluded that the presence in the intestine of substantial amounts of alcohol temporarily destabilises the intercellular junctions of the epithelium and thus promotes the absorption of materials which are normally excluded.Absorption from the healthy adult gastrointestinal tract of immunologically significant amounts of macromolecular material is well documented and has been reviewed.' Recent investigations of this phenomenon have used the administration of test antigens by gavage to experimental mice2 or by normal ingestion in human volunteers.3 In such situations it is not clear at which point in the gastrointestinal tract that the absorption occurs, and the role of minor traumatic lesions in the gums, oesophagus, or stomach cannot be excluded totally. In order to lessen these problems we decided to measure the absorption of antigen in rats in terms of its appearance in thoracic duct lymph, which comes principally from the small intestine and which is an obligatory pathway for any macromolecular material which has traversed intestinal wall.5 In spite of recent claims for substantial uptakes of protein antigens by tile gut of rats6 we were unable to detect in our preliminary experiments any absorption of horseradish peroxidase after a 10 mg dose of the purified enzyme had been instilled into the lumen of the duodenum. We observed, ' On sabbatical leave from the

On the basis of [3H]thymidine incorporation by normal mouse spleen cell cultures, cell wall preparations from a smooth (45/0) strain and a rough (45/20) strain ofBrucella abortus were strongly mitogenic. On the other hand, none of several subcomponents, extracted from the cell wall preparations, including aqueous and phenolic lipopolysaccharides, was active. These results contrast with the marked mitogenic activity of lipopolysaccharides isolated from other gram-negative bacteria such as Salmonella typhimurium.

No abstract

Frozen rabbit immunoglobulin G was exposed to high-energy electrons. The surviving polypeptide subunits were determined and analyzed by radiation target analysis. Each subunit was independently damaged by radiation whether or not they were bound by disulfide bridges to other subunits, demonstrating that in IgG radiation-deposited energy did not travel across disulfide bonds.

Serial dilution with Takatsy loops resulted in exaggerated passive hemagglutination titers with most of the anti-bovine serum albumin sera tested. It appears that certain types of agglutinins adhere to the loop surface and are released only gradually. This adherence, or carry-over effect, was prevented by presoaking loops in gelatin or gelatin-rabbit serum-albumin solutions. Hemolysins did not adhere to loops. In general, hemagglutination reactions performed on plastic trays gave higher titers than those performed in glass test tubes. The quality of the hemagglutination pattern was dependent to a great extent on the type of plastic tray used. As much as a 100-fold difference in titers was obtained depending on the composition of the antiserum diluent. The increase in vibration, in terms of linear displacement (approximately twofold), resulted in an eightfold decrease in titers. Although the passive hemagglutination (HA) test is one of the most simple and widely used immunological assays, it lacks reproducibility. I This study was performed in part while one of the authors (L.R.D.) was associated with the National Cancer Institute,