Electron microscopic observations on antibody-producing cells in lymph and blood.

Antibody-producing cells have been identified among cells obtained from efferent lymphatic vessels, the thoracic duct, and peripheral blood. These cells, which produced plaques of hemolysis and which were quite rare (20 to 50 per million), due in most instances to 19S antibody, were located and studied by electron microscopy. Of the antibody-producing cells found in these three sites there were several features common to all: small size (5 to 8 micro), generally spherical shape, approximately central position of the nucleus, and retention in the nucleus of the condensations of chromatin characteristic of the lymphocyte. The differences among the cells of these sources were largely in the relative amount and state of organization of the organelles of the cytoplasm. In cells of the efferent lymphatic vessel and the thoracic duct, the endoplasmic reticulum showed a range from relative scarcity to considerable numbers of well organized channels. Between these extremes were cells with a considerable amount of endoplasmic reticulum, the channels disorganized and sectioned at various angles. The cytoplasmic matrix of all of these contained a profusion of polyribosomes. Antibody-producing cells obtained from peripheral blood showed, around the roughly spherical nucleus, a ring of cytoplasm which was narrow, but wholly organized into parallel lamellae of endoplasmic reticulum, with many polyribosomes between these, and a large Golgi body. Some similarities and some differences of these cells, in comparison with antibody-producing cells obtained from lymph nodes, have been indicated.

A Paneth cell analogue in Xenopus small intestine expresses antimicrobial peptide genes: conservation of an intestinal host-defense system.

Antimicrobial peptides are a widespread component of host defense. We characterized the tissue distribution and cellular localization of expression of the magainin family of antimicrobial peptide genes in Xenopus laevis. Two genes from this family, magainin and PGLa, are expressed at high levels in the skin and throughout the gastrointestinal tract. Magainin and PGLa mRNAs are synthesized in the granular multinucleated cell (GMC) of the gastric mucosa, a cell shown previously to contain magainin and PGLa peptides by immunohistochemical methods. In addition, we have localized magainin and PGLa mRNAs to distinct cells of Xenopus small intestine. Further characterization of this large, granule-filled cell by electron microscopy demonstrates features in common with the Paneth cell of mammalian small intestine, previously identified as a site of expression of antimicrobial peptide genes of the defensin family in mouse and human. Our identification of granule-laden, eosinophilic intestinal cells in Xenopus as a site of magainin and PGLa antimicrobial peptide gene expression suggests that these cells are functional analogues of mammalian Paneth cells and further supports a conserved role of antimicrobial peptides in host defense of the vertebrate small intestine.

A novel peptide-producing cell in Xenopus: multinucleated gastric mucosal cell strikingly similar to the granular gland of the skin.

We have characterized a novel peptide-containing cell within the gastric mucosa of Xenopus laevis. The cell is a spherical, multinucleated syncytial structure containing a cytoplasmic space filled with dense rice-shaped granules, and is strikingly similar in morphology to the well-studied granular gland of the amphibian skin. Immunohistochemical and immunogold methods were used to demonstrate that several peptides previously isolated from the granular glands of the skin, including the antimicrobial peptides magainin and PGLa (a peptide with amino-terminal glycine and carboxy-terminal leucinamide), are also stored in granules present in these enteric cells. These data demonstrate that this enteric peptide-producing cell is strikingly similar both morphologically and biochemically to the granular gland, previously considered a highly specialized structure of the amphibian integument. This novel gastric mucosal cell, which we have designated a "granular multinucleated cell," is distinct in its morphology and its diversity of stored peptide products from other well-characterized peptide-containing cells in the vertebrate gastrointestinal tract.

Reversibility of morphine effects on phagocytosis by murine macrophages.

Proneness of addicts to infections may be partially due to opiate effects on immune cells. We find that acute morphine inhibits phagocytosis in murine peritoneal macrophages in vitro with apparent desensitization at high concentrations, whereas chronic exposure results in a state akin to tolerance/dependence where macrophages seem to require morphine to phagocytize at a control level. However, both putative desensitization and tolerance/dependence are reversible, since drug re-addition several hours after withdrawal results in inhibition, as in acute exposure. This shows that opiate effects on immune cells are variably related to the experimental context in which they are administered, which is of relevance for understanding their potential role in immunosuppression.

[Papillomatosis of the bile ducts: a clinical case]. / Papillomatosi vie biliari: caso clinico.

A case of diffuse papillomatosis of the bile duct, treated with external biliary drainage, is reported on account of its rarity. The extent and anatomopathological characteristics of the lesion make radical surgery impossible, so that the above-stated surgical solution appears to the Authors to be the most suitable one for resolving the biliary stasis and consequent cirrhosis.

[Biliary ileus: reflections on one clinical case (author's transl)]. / Ileo biliare: considerazioni su di un caso clinico.

The authors describe one case of biliary ileus occurring in the form of stepwise intestinal obstruction, successfully treated by surgery designed to resolve the obstruction and at the same time repair the biliodigestive fistula. Because of the high postoperative morbidity and mortality in emergency cases, this operation should be reserved in the authors' opinion to patients in satisfactory humoral balance and in the absence of general contraindictions.