The glycoproteins of secretory cells in airway epithelium

Quantitative histochemical methods demonstrate a variety of glycoproteins within mucus-secreting cells of airway epithelium. A single cell may synthesize one or a combination of four major types--(i) neutral glycoprotein, (ii) and (iii) sialylated either sensitive or resistant to sialidase and (iv) sulphated. In human airway disease, or in experimental response to inhalation of an irritant, there is mucus cell hyperplasia and change in the proportion of cells synthesizing the various types. Experimental studies show how speedily these changes occur. In rats exposed to tobacco smoke changes are found within 20 h of the first exposure. Only in the extrapulmonary epithelium is there discharge of the secretions, with an apparent fall in cell number. Modification of glycoprotein may occur with an unchanged or increased cell number, suggesting that it occurs in existing and newly appearing secretory cells. Modification of the contents of the granule occurs toward the cell apex. Modification of glycoprotein synthesis towards the normal is also the most sensitive and earliest sign of recovery.

Electron microscopic analysis of the specific granule content of human atria. An investigation of the role of atrial pressure and atrial rhythm in the release of atrial natriuretic peptide

Knowledge about the stimulus for the release of atrial natriuretic peptide (ANP) from human atria is incomplete. Atrial stretch is known to be a stimulus and atrial tachyarrhythmias are thought to be another. The effects of atrial size (by two-dimensional echocardiography) and atrial fibrillation on the atrial specific granule content of human atria were studied to gain insight into the secretory mechanisms of ANP. An electron microscopic analysis of the atrial granule content was used to study 12 patients--5 with mitral stenosis and sinus rhythm, 3 with mitral stenosis and atrial fibrillation and 4 controls. Granules were counted using a free count and montage method. This is the first report of such a morphometric analysis in humans. Granule counts were significantly raised in the patients with mitral stenosis compared with controls (P less than 0.014). This observation probably reflects a high turnover state induced by elevated atrial pressures. Further support for this conclusion is provided by the demonstration of a positive correlation between granule counts and left atrial size (r = 0.86; P less than 0.01). The tendency for higher counts in patients with atrial fibrillation may be related to the rhythm disturbance itself, but clinical and echocardiographic data suggest more severe atrial pressure overload in this group.

Immunogold probing of platelet factor 4 in different ploidy classes of rat megakaryocytes sorted by flow cytometry

Different ploidy classes of rat megakaryocytes were sorted by flow cytometry from highly purified perfusion-fixed megakaryocyte cell suspensions prepared by sequential centrifugal elutriation and Percoll gradient centrifugation. Sorted cell populations were studied for the localization of platelet factor 4 (PF-4) probed with the monoclonal antibody 2E7 in order to clarify the relevance of PF-4 localization to the cytoplasmic and nuclear development of megakaryocytes. The relative numbers of labeled alpha granules and labeled alpha granule-related small vesicular structures (AGR-SVS) were quantitated using the gold-labeled antibody detection method and correlated with DNA content and cytoplasmic maturation in individual megakaryocytes. We determined that the stage of cytoplasmic maturation exerted a significant effect on the proportion of labeled alpha granules and labeled AGR-SVS. A significant interaction effect of stage and ploidy class resulted in the stage effect on proportion of labeled alpha granules being significant only in two of the three ploidy classes. The least mature cells present within each ploidy group exhibited PF-4 labeling mostly in SVS that were not related to alpha granules. During subsequent cytoplasmic maturation, more of the labeled SVS were seen related to alpha granules, with more of the mature alpha granules themselves becoming labeled. Polyploidization also affected the proportion of labeled AGR-SVS. Our data suggest that SVS play a role in the intramegakaryocytic transport of PF-4 into alpha granules. These data provide evidence of the complexity of megakaryocytic differentiation involving both cytoplasmic maturation and nuclear endoreduplication as reflected in PF-4 expression.

Atrial natriuretic factor in the vena cava and sinus node

We investigated the localization of atrial natriuretic factor (ANF) mRNA and of immunoreactive ANF in the vena cava and sinus node of rat and, for comparative purposes, in atria and ventricles. In situ hybridization with an ANF cRNA probe revealed that the supradiaphragmatic portion of the inferior vena cava contains almost as much mRNA as the atria, whereas the levels were less in the superior vena cava and higher than in ventricles in the sinus node. Immunoreactive ANF (high Mr form) was found to be 22 times less abundant in the supradiaphragmatic vena cava and 148 times less abundant in the superior vena cava than in atrial cardiocytes. The wall of the supradiaphragmatic portion of the vena cava and the valve (eustachian valve) that separates the atrial cavity from that of the vein are made up of atrial-like cardiocytes containing secretory granules. The subendothelial area of the superior vena cava also contains atrial-like cardiocytes with secretory granules, whereas the outer portion of the vein is made up of "transitional cells" without or with only a few secretory granules. Secretory granules in the vena cava and nodal cells, as well as transitional cells, contain immunoreactive ANF. With immunocryoultramicrotomy, virtually all cells, whether atrial-like, transitional, or nodal, and even those without secretory granules, were found to contain immunoreactive ANF in their Golgi complex and in secretory vesicles in the vena cava and in the sinus node.

Subcellular localization of blood group substances ABH in human salivary glands

We investigated the subcellular localization of ABH antigens in human submandibular, sublingual, and buccal glands by applying a post-embedding immunogold method using monoclonal antibodies specific for A, B, and H antigens. In most glands the immunoreactivity was usually restricted to mucous cells, in which only secretory granules and sometimes Golgi cisternae were specifically labeled. A and B antigens were demonstrated only in the glands of type A, B, and AB subjects, while H antigen was visualized in glands from individuals of all blood types. Moreover, differences were observed in the relative distribution of ABH antigens, depending on the type of gland.

Cytoplasmic components of natural killer cells limit the growth of Cryptococcus neoformans

Murine natural killer (NK) cell-mediated inhibition of growth of a yeast-like target cell, Cryptococcus neoformans, was completely abrogated by blocking the effector cell secretory process with monensin. Therefore, further studies were performed to determine the ability of various cytoplasmic fractions of NK cells to mediate inhibition of cryptococcal growth. Percoll-fractionated homogenates of rat LGL tumor cells demonstrated that the granule-containing fractions plus three additional sets of less dense cytoplasmic fractions displayed anti-cryptococcal activity; whereas only the cytoplasmic granule-containing fractions had cytotoxic activity against YAC-1 tumor cell and sheep erythrocyte targets. Maximal cryptococcal growth inhibition induced by LGL granules occurred after a 1 h incubation, required the presence of Ca2+ (1.0 mM) or Mg2+ (0.5 mM or 5.0 mM), and was completely abrogated in the presence of rabbit anti-LGL granule IgG. Cytolysin, the granule component which mediates tumor cell and sheep erythrocyte lysis, effectively limited the growth of cryptococci. Since Percoll gradient fractionation of the LGL homogenates demonstrated three separate peaks of anti-cryptococcal activity other than the granule peak, it is possible that the cytolysin-containing granules are not the only subcellular component of NK cells playing a role in inhibition of C. neoformans growth.

Ultrastructural localization of the putative precursors of the A4 amyloid protein associated with Alzheimer's disease

Any explanation of the causes of Alzheimer's disease and of its unique cerebral pathologic features must take into account the distribution and ultrastructural localization of the pre-A4 amyloid proteins in tissues and organs. The authors have analyzed the expression of the pre-A4 amyloid proteins in several tissues by immunogold electron microscopy and by immunofluorescence. For this purpose, they have used a mouse monoclonal antibody and a guinea pig antiserum raised against two synthetic peptides corresponding to two different sequences common to all the full-length forms of the A4 amyloid precursors. They observed a tissue-specific distribution of the secreted and the transmembrane form of the precursors. The authors could determine that the secreted form is generated in vivo within the cytoplasm. In the salivary glands and in the adenohypophysis, all the immunoreactivity is associated with the process of secretion, whereas in the muscle, a staining pattern compatible with the presence of the pre-A4 amyloid proteins in the sarcoplasmic reticulum has been observed. This difference in the localization may reflect tissue-specific processing pathways and suggests that posttranslational modifications such as proteolytic removal of the transmembrane and cytoplasmic domains contribute to the structural and thus functional diversity of the A4 amyloid precursors.

Estrogen increases galanin immunoreactivity in hyperplastic prolactin-secreting cells in Fisher 344 rats

Galanin is a widely distributed regulatory peptide which modulates the pituitary secretion of PRL and GH. Estrogen administration strongly stimulates galanin gene expression in the rat anterior pituitary. In adult female Fischer 344 rats, estrogen also induces hyperplasia of lactotropes. We used immunocytochemical analysis to assess the effects of estrogen on galanin-like immunoreactivity (Gal-IR) in the rat pituitary and hypothalamus during sc diethylstilbestrol (DES) implantation and after its removal at 30 days. In the anterior pituitary, DES implantation increased the portion of Gal-IR-containing cells from less than 2% in the control rats to 18.3% after 3 days of DES and 36% after 30 days. These changes paralleled the lactotrope hyperplasia exhibited in response to DES exposure. Ten and 30 days after removal of the DES capsules, the percentage of Gal-IR-containing cells in the anterior pituitary decreased to 6.3% and 1.5%, respectively. Colocalization studies revealed that Gal-IR-containing cells were predominantly lactotropes. Immunoelectron microscopy demonstrated that Gal-IR was concentrated in the Golgi region of these hyperplastic lactotropes and suggests that little of the synthesized galanin is secreted. The distribution of Gal-IR in the hypothalamus, median eminence, and neurohypophysis was unaffected by DES treatment. These data demonstrate that galanin is synthesized by hyperplastic pituitary lactotropes of Fischer 344 rats and that peptide accumulation is dependent on the presence of circulating estrogens. In contrast, neuronal galanin synthesis in the hypothalamus does not appear to be regulated by estrogen.

Immunocytochemical studies on the localization of pancreatic-type phospholipase A2 in rat stomach and pancreas, with special reference to the stomach cells

Using a specific polyclonal antibody raised against rat pancreatic phospholipase A2 (PLA2), we investigated the localization of the enzyme in the rat pancreas and stomach by light and electron microscopy. In the pancreas, the enzyme was localized in the acinar cells, whereas the pancreatic islets showed no immunoreaction. In the stomach, the PLA2 reactive with the anti-pancreatic PLA2 antibody was distributed exclusively in the gastric glands, but not in the gastric pits or the pyloric glands. On the section of the stomach subjected to immuno- and PAS-staining, immunopositive cells were not the PAS-positive cells located in the gastric pit and the neck region of the gastric gland. Immunopositive cells were present from the neck to the bottom of the gastric gland. Immunoelectron microscopic observation revealed that the immunogold-labeled cell had a highly-developed rough endoplasmic reticulum in the basal cytoplasm and characteristic zymogen granules in the apical cytoplasm. Taking into account the cell position in the gastric gland, the immunopositive cell could therefore be identified as a chief cell. Since no double stainability with PLA2 and PAS was observed in the same cell, it is suggested that PLA2 could be used cytochemically as a marker enzyme of the chief cell in the gastric gland at the light-microscopic level. From the immunoelectron microscopic findings, we believe that the PLA2 in the stomach is released into the lumen of the stomach by exocytosis and could function as a digestive enzyme in the alimentary tract, like the PLA2 secreted from the pancreas. Other possible roles of the PLA2 in the stomach are discussed.

Lymphotoxin induces secretion of granule proteins from adherent neutrophils: possible role of intracellular free calcium

Lymphotoxin (LT) can activate human neutrophils. Using a hemolytic plaque assay to detect secretion of lactoferrin and myeloperoxidase (MPO) from single adherent neutrophils, we showed that LT induced secretion from both primary and secondary granules. Incubation of cells with cytochalasin B was required for MPO secretion, and it enhanced lactoferrin secretion. Pertussis toxin, which blocks a G-protein in the plasma membrane, inhibited LT-induced exocytosis of MPO, but not of lactoferrin. Incubation with LT did not induce any detectable changes of the cytoplasmic free [Ca2+] in neutrophils. On the other hand, secretion of granule proteins from adherent neutrophils in response to LT was blocked by loading neutrophils with quin-2 in order to increase the intracellular calcium buffering capacity. This was achieved at a concentration of quin-2, at which the secretion induced by the phorbol ester PMA and the chemotactic peptide FMLP was unaffected. Trifluoroperazine (TFP), a dual protein kinase C and calmodulin inhibitor, significantly inhibited the LT-mediated secretion of lactoferrin from adherent granulocytes. The PMA effect was unaltered by TFP under these conditions, suggesting that the inhibitory effect was on a calcium-calmodulin dependent step. The secretion induced by TNF and GM-CSF was also blocked by buffering changes in the intracellular [Ca2+] and inhibited to a similar extent by TFP. Our results suggest that calmodulin and minute changes in the cytoplasmic free [Ca2+] may be involved in a common signal transduction pathway engaged in activation of adherent neutrophils by several cytokines.

Ultrastructural identification of human secretin cells by the immunogold technique. Their costorage of chromogranin A and serotonin

We have localized secretin in a morphologically distinctive endocrine cell scattered in the epithelium covering the villi and uppermost crypts of the human duodenum and jejunum. The human secretin cell was characterized by relatively large (mean diameter 299 nm +/- 69 SD), fairly irregular granules, the majority of which showed homogeneous distribution of secretin and chromogranin A immunolabelling in a structurally homogeneous core. Other granules had a targetoid pattern due to an inner, argyrophobe, secretin-immunoreactive body surrounded by an argyrophil, chromogranin A immunoreactive mantle. These targetoid granules represent a distinctive ultrastructural marker of the secretin cell. Secretin cell granules have been shown to react with chromogranin A antibodies and Grimelius' silver, while lacking chromogranin B immunoreactivity. About 1/3 of secretin cells also showed serotonin immunostaining.

Chromogranins A and B are co-localized with atrial natriuretic peptides in secretory granules of rat heart

We investigated the occurrence and subcellular localization of chromogranins A and B in atrial myoendocrine cells of rat heart, using immunological methods. Immunoblotting revealed the presence of both chromogranin A and B in an extract from large granules isolated from this tissue by subcellular fractionation. Immunohistochemistry at the ultrastructural level demonstrated the presence of chromogranin A and B in secretory granules. These organelles also immunostained for atrial natriuretic peptides (ANP). Within a given section, all granules were labeled with immunogold for these three antigens. This apparent co-localization of the three antigens was confirmed by double immunostaining with immunogold particles of different sizes. We conclude that, in agreement with their endocrine nature, the secretory organelles of rat atria contain both chromogranins A and B. Apparently these acidic peptides, which have a widespread distribution in the endocrine system, are co-stored and therefore also co-secreted with ANP.

Localization of fibrinogen during ADP- or thrombin-induced aggregation of washed rabbit platelets

In contrast to human platelets, which aggregate poorly in response to ADP unless fibrinogen is present in the external medium, washed rabbit platelets form large aggregates in response to ADP without fibrinogen in the suspending medium. Addition of fibrinogen to the suspending medium of rabbit platelets frequently has little or no effect on the extent of ADP-induced platelet aggregation. We examined washed rabbit platelets by immunocytochemistry during ADP-induced aggregation and deaggregation and during thrombin-induced aggregation when the external medium did not contain added fibrinogen to determine if (a) fibrinogen was expressed on the surface of rabbit platelets that could support aggregation when the platelets were stimulated, or (b) fibrinogen secreted from the alpha granules supports platelet aggregation. Glutaraldehyde-fixed samples were prepared at different times after addition of ADP or thrombin, embedded in Lowicryl K4M, sectioned, incubated with sheep anti-rabbit fibrinogen, washed, reacted with gold-labeled anti-sheep IgG, and prepared for electron microscopy. The alpha granules of rabbit platelets were heavily labeled with immunogold; the platelet membrane was not labeled. During platelet aggregation and deaggregation in response to ADP, fibrinogen was not detectable on the platelet surface. In response to thrombin, large aggregates formed before fibrinogen was secreted from the alpha granules; fibrinogen was detectable focally at sites of granule discharge by 30-60 sec and fibrin formed by 3 min. Therefore, stimulated washed rabbit platelets can adhere to each other without large amounts of fibrinogen taking part in the close platelet-to-platelet contact, since aggregation occurs before detectable secretion, and large areas where the platelets are in contact are devoid of fibrinogen between the adherent membranes. Adhesion mechanisms not involving fibrinogen may support the aggregation of washed rabbit platelets.

Calcium release from pituitary secretory granules: modulation by thiols, disulfides, and dihydropyridine calcium channel blockers

The distribution of calcium in isolated bovine pituitary secretory granules was studied by atomic absorption. The total granule calcium (in 26 preparations) averaged 14.5 nmol/mg protein, or 21.2 +/- 1.6% of the total pituitary homogenate calcium. Incubation of granules with KCl resulted in calcium release (78% at 15 mM and 100% at 50 mM, for example). Calcium release was also pH dependent, with greater release at acidic pH values; it was not influenced by either 500 microM strontium or 500 microM lanthanum. Release was augmented by reduced glutathione (GSH), with significant release observable at thiol levels as low as 10 microM. In addition to GSH, cysteine also stimulated release; mercaptoethanol and dithiothreitol were less potent. Interestingly, the disulfides cystine and oxidized glutathione also stimulated calcium release. Since the latter compounds are known to inhibit hormone release from granules, calcium and protein release appear to be regulated independently. A number of dihydropyridines were tested as potential blockers of calcium release from granules. Nimodipine inhibited basal calcium release at high concentrations and potently inhibited GSH-stimulated calcium release, with an apparent Ki in the 10-20 nM range; it also inhibited K(+)-stimulated release but to a lesser extent. Nimodipine, however, did not significantly influence protein or hormone release. GSH-stimulated calcium release was also inhibited by nifedipine, and this inhibition was qualitatively and quantitatively similar to that by nimodipine. Nisoldipine and nitrendipine, however, displayed no significant inhibition. In summary, it appears that the release of secretory granule calcium in vitro is independent of protein release. Thiols and some disulfides stimulate calcium release, and its inhibition by dihydropyridines suggests that granule membranes may contain specific ion channels. The role of granule calcium in the cell remains to be defined.

Culture and characterization of human tracheal gland cells

In order to study the composition and regulation of human tracheal gland (HTG) cell secretion, we cultured HTG cells isolated by enzymatic digestion from tracheal mucosa obtained 30 to 60 min after death. On microscopic observation, isolated cells were mainly composed of secretory glandular cells. Maximal HTG cell growth was observed when cells were cultured on type I collagen in the presence of 2% Ultroser G. Under these conditions, 3 to 6 HTG cell passages, corresponding to 20 to 30 population doublings, could be achieved. Lysozyme and bronchial inhibitor (Brl), two secretory protein markers specific to the serous HTG cells, were released in the culture medium, maximal secretion being observed 7 days after the cells had reached confluency. At that time, Brl could be detected, with an immunoperoxidase technique, in about 90% of the cells in culture, suggesting that most cells in culture were serous cells. Using transmission electron microscopy, after in situ fixation, HTG cells exhibited an epithelioid appearance at confluency. Using the biotin-streptavidin gold technique, we identified Brl in cytoplasmic vesicles and in small, immature electron-dense secretory granules. In high cell density cultures, we observed dome formation, suggesting active ion transport mechanisms in HTG cell culture. At confluency, a dose-dependent increase of Brl secretion was induced by phenylephrine, isoproterenol, and carbochol. These results suggest that HTG cell culture provides a useful tool to study the biochemistry and regulation of human tracheobronchial gland cell secretion.

Concurrence of transient asplenia and pure red cell aplasia

We report a 9-year-old male with anatomical asplenia diagnosed at 7 months of age documented by ultrasound and liver-spleen scan which resolved spontaneously 3 years later. The patient concurrently had pure red cell aplasia which subsequently resolved spontaneously.

Secretory glycoproteins of the rat subcommissural organ are N-linked complex-type glycoproteins. Demonstration by combined use of lectins and specific glycosidases, and by the administration of Tunicamycin

Two experimental protocols were used to investigate the secretory glycoproteins of the subcommissural organ (SCO). Protocol I: Lectins, specific exoglycosidases and immunocytochemistry were sequentially applied to the same section or to adjacent semithin sections of the rat SCO fixed in Bouin's fluid and embedded in methacrylate. Lectins used: concanavalin A (con A), wheat germ agglutinin, Limulus polyphemus agglutinin, Ricinus communis agglutinin and Arachis hypogeae agglutinin. Glycosidases used: neuroaminidase, beta-galactosidase, alpha-mannosidase, alpha-glucosidase and beta-N-acetyl-glucosaminidase. For immunocytochemistry an antiserum against bovine Reissner's fiber (AFRU) was used. Lectins and glycosidases were used in sequences that allowed the cleaved sugar residue to be identified as well as that appearing exposed as a terminal residue. This approach led to the following conclusions: (1) the terminal sugar chain of the secreted glycoproteins has the sequence sialic acid-galactose-glucosamine-; (2) the con A-binding material present in the rough endoplasmic reticulum corresponds to mannose; (3) the apical secretory granules and Reissner's fibers displayed a strong con A affinity after removing sialic acid, thus indicating the presence of internal mannosyl residues in the secreted material; (4) after removing most of the sugar moieties the secretory material continued to be strongly immunoreactive with AFRU. Protocol II: Rats were injected into the lateral ventricle with Tunica-mycin and killed 12, 24, 50 and 60 h after the injection. The SCO of rats from the last two groups showed a complete absence of con A binding sites. The results from the two experiments confirm that the secretory glycoproteins of the rat SCO are N-linked complex-type glycoproteins with the conformation previously suggested (Rodríguez et al. 1986).

Alveolar soft-part sarcoma of the tongue. Report of a case

A case of alveolar soft-part sarcoma (ASPS) of the tongue in a 19-year-old boy is presented. He underwent a hemiglossectomy and received chemotherapy and has been free of disease for 3 years. The origin of intracytoplasmic periodic acid-Shiff(PAS)-positive crystals found in the tumor and the histogenesis of ASPS are briefly discussed.

Histological changes in cardiac hemochromatosis improved by an iron-chelating agent. A biopsy case

Cardiac dysfunction and ECG abnormalities were demonstrated in a 51-year-old woman suffering from secondary hemochromatosis in sideroblastic anemia. Hemosiderin deposition in vacuolized and disarrayed myocytes was disclosed by microscopic examination of the first biopsy specimen of endomyocardial tissue. Three months after administration of deferoxamine mesylate, an iron-chelating agent, the clinical findings were improved. The second endomyocardial biopsy revealed marked depletion of hemosiderin deposition in the myocytes, and improvement of myocyte vacuolization and disarray. Ultrastructurally, the highly electron-dense granules in the myocytes were also decreased in number and density. X-ray microanalysis revealed a prominent peak of Fe in the granules. In a liver specimen obtained by needle biopsy 5 months after the second endomyocardial biopsy, marked hemosiderin deposition still remained.

[Microspectrofluorometric analysis of the effect of centrophenoxine on lipofuscin granules of hybridoma (Retrovirus-transformed) cells]

The increase of the own luminescence lipofuscin granules (LG) in the course of single and repeated ultraviolet (UV) excitations (365 nm) in hybridoma (retrovirus transformed) cells cultured with or without 5 x 10(-4) M centrophenoxine (CP) was studied by microspectrofluorometric method. It was shown that CP influences only the rate of photochemical changes of chromophores in LG. Kinetic patterns of the own luminescence intensity of LG at the wavelength of 540 nm during excitation by UV permit one to suggest the occurrence of the cyclic chromophore changes.

Observations on pigment granules in the bones of silky fowls

The distribution of melanin pigment-containing cells in the bones of both young and adult silky fowls was observed. Melanin pigment was detected not only in melanocytes which were mainly distributed in the periosteum, but also in all the other types of cells in the periosteum and bone. The continuity of the number of pigment granules in melanocytes and that in the other pigment-containing cells could not be recognized because the granules in the latter cells were much fewer than those in the former. In young fowls, the pigment-containing cells were distributed in all layers of the periosteum and bone, but their number was low. On the other hand, in aged fowls, most of the cells in the periosteum had pigment granules. In the bone, however, pigment granules were observed only in osteocyte situated near the surface. These findings suggest that the pigment granules which are observed in osteocytes have been transferred from melanocytes to osteogenic cells or osteoblasts before they differentiate to osteocytes, where they are presumed to be digested.

Mixed enzyme-linked immunosorbent assay (MELISA) for HLA class I antigen: a plasma membrane marker

This study introduces a simple, reproducible assay for HLA class I antigen using antibodies against beta 2-microglobulin and the heavy chain on HLA. The sandwich technique was named mixed enzyme-linked immunosorbent assay (MELISA), and was designed for identification of plasma membranes in neutrophil subcellular fractions. The subcellular localization of HLA was identical to that of other plasma membrane markers, [3H]concanavalin A and detergent-independent alkaline phosphatase, and was unchanged by stimulation of cells by weak and strong secretagogues. In addition to the presence as part of the HLA complex in the plasma membrane uncomplexed beta 2-microglobulin is present in the specific granules of neutrophils. However, the release of beta 2-microglobulin from intact neutrophils stimulated with formyl-methionylleucylphenylalanine was much higher than could be explained by exocytosis of specific granules. Subcellular fractionation studies demonstrated that beta 2-microglobulin is localized in fractions characterized by latent alkaline phosphatase and released from this novel secretory compartment in response to stimulation with formyl-methionylleucylphenylalanine.

Occurrence of hydrin 2 (vasotocinyl-Gly), a new hydroosmotic neurohypophyseal peptide, in secretory granules isolated from the frog (Rana esculenta) neurointermediate pituitary

Neurohypophyseal secretory granules have been purified from the frog (Rana esculenta) neurointermediate pituitary gland by sucrose gradient centrifugation, and their polypeptide content has been analyzed by reverse-phase high-pressure liquid chromatography. Aside from vasotocin, mesotocin, and their associated neurophysins, hydrin 2 (vasotocinyl-Gly), previously identified in hydrochloric acid extracts, has been recognized. This finding supports the previous suggestion that hydrin 2, a peptide active on the water permeability of frog bladder and frog skin, is a secreted hormone involved in osmoregulation specific to amphibians. Hydrin 2 has not been found in neurosecretory granules of birds such as the goose.

Identification of a highly mobilizable subset of human neutrophil intracellular vesicles that contains tetranectin and latent alkaline phosphatase

Tetranectin, a protein recently identified in a wide variety of human secretory cells (Christensen, L., and I. Clemmensen. 1989. Histochemistry. 92:29-35) was found to colocalize with latent alkaline phosphatase activity in fractions well separated from azurophil granules, specific granules, gelatinase-containing granules, and plasma membranes when postnuclear supernatants of nitrogen-cavitated neutrophils were fractionated on discontinuous Percoll density gradients. Stimulation of intact neutrophils with nanomolar concentrations of FMLP, leukotriene B4, 10-100 U/ml of tumor necrosis factor, and granulocyte-macrophage colony-stimulating factor resulted in parallel release of tetranectin and translocation of alkaline phosphatase to the plasma membrane. Furthermore, intracellular pools of tetranectin and latent alkaline phosphatase were completely released from neutrophils under conditions that barely induced release of specific granules containing B12-binding protein. These findings indicate that tetranectin and latent alkaline phosphatase define an easily mobilizable population of cytoplasmic storage organelles in human neutrophils which are functionally distinguishable from azurophil, specific, and gelatinase-containing granules. These organelles may play an important role as stores of membrane proteins that are mobilized to the cell surface during stimulation by inflammatory mediators.

Uptake of ascorbic acid by freshly isolated cells and secretory granules from the intermediate lobe of ox hypophyses

Mechanically isolated cells from the intermediate lobe of ox hypophyses contained 40.6 +/- 3.7 nmol mg-1 protein (mean +/- SE, n = 5) of ascorbic acid. They accumulated radioactivity time dependently, on incubation with L-[14C]ascorbic acid in ionic medium dominated by NaCl. No definite saturation of uptake occurred when mechanically isolated cells were incubated with increasing ascorbic acid concentrations up to 0.6 mM. But if such cells were purified on a Percoll gradient, a clear saturation of uptake could be observed. Acetylsalicylic acid reduced the uptake markedly. When cells loaded with L-[14C]ascorbic acid were homogenized and placed on a Percoll gradient, the radioactivity was recovered in several subcellular fractions. Decrease of the Na+ concentration or presence of ouabain in the medium did not cause noticeable changes in uptake by non-purified cells, whereas uptake by purified cells was clearly sodium-dependent. Phloridzin inhibited uptake. Secretory granules from pars intermedia contained 40.0 +/- 3.8 nmol mg-1 protein of ascorbic acid (mean +/- SE, n = 3) and could accumulate L-[14C]ascorbic acid rapidly in a KCl-dominated medium. The uptake was not saturable with ascorbic acid concentration and was not influenced by the presence of I mM ATP + I mM Mg2+ in the medium. The concentration of copper and iron in isolated cells was comparable to that in isolated neurohypophysial nerve terminals, whereas the concentration of zinc was considerably higher in the pars intermedia cells. The concentration of Cu, Zn, Fe and Co in secretory granules from pars intermedia was higher than in secretory granules from neurohypophyses.

Bicomponent keratohyalin in normal human ridged skin

Up to now, bicomponent keratohyalin has only been described for rat epithelium and human intraepidermal sweat ducts and fetal nail organ cells. In normal human interductal epidermis, the keratohyalin appears homogeneous, osmiophilic and stellate in shape. Under pathological conditions, bicomponent keratohyalin has been observed in different palmoplantar keratoses and has therefore been thought to be associated with abnormal keratosis. We studied the keratinization process in normal human plantar epidermis, in which keratohyalin was found to exhibit several morphological differences as compared to that seen in non-ridged skin. The most striking feature was seen in upper granular cells, where the keratohyalin granules consisted of two components of differing electron density. The electron-dense component formed the main part of the composite granule and was found in the cytoplasm of lower and upper granular cells. The less-electron-dense component was attached to the main component and appeared in the cytoplasm of upper granular cells, forming the convex contact zone. No intranuclear osmiophilic inclusions were present. The respective electron densities of the two keratohyalin components of ridged skin were obviously different to that of the bicomponent keratohyalin granules seen in the epidermal sweat-duct cells of the same specimen. These findings indicate the presence of at least two different types of keratohyalin proteins in normal human ridged skin. They can be distinguished at the electron-microscope level and differ from the keratohyalin of human non-ridged skin as well as from bicomponent keratohyalin granules derived from human epidermal sweat-duct cells or from rat epithelium.

Secretory glycoconjugates of a mucin-synthesizing human colonic adenocarcinoma cell line. Analysis using double labeling with lectins

Lectins were used to characterize mucin glycoproteins and other secretory glycoconjugates synthesized by a human colon adenocarcinoma-derived cell line which expresses a goblet cell phenotype. Despite being clonally derived, HT29-18N2 (N2) cells, like normal goblet cells in situ were heterogeneous in their glycosylation of mucin. Only wheat-germ agglutinin, which recognizes N-acetylglucosamine and sialic acid residues, and succinylated wheatgerm agglutinin, which binds N-acetylglucosamine, stained the contents of all secretory granules in all N2 goblet cells. The N-acetylgalactosamine binding lectins Dolichos biflorus and Glycine max stained 20% and 21% of N2 goblet cells respectively. Ricinus communis I, a galactose-binding lectin, stained 67% of N2 goblet cells although staining by another galactose-binding lectin, Bandeiraea simplicifolia I, was limited to 19%. Peanut agglutinin, a lectin whose Gal(beta 1-3)GalNAc binding site is not present on mucins produced in the normal colon but which is found on most mucins of cancerous colonic epithelia, stained 68% of the cells. Ulex europeus I, a fucose-binding lectin, did not stain any N2 goblet cells. Four lectins (Lens culinaris, Pisum sativum, Phaseolus vulgaris E, Phaseolus vulgaris L) which recognize sugars normally present only in N-linked oligosaccharides stained up to 38% of N2 goblet cells. The binding of these lectins indicates either both O-linked and N-linked oligosaccharide chains are present on the mucin protein backbone or the co-existence of non-mucin N-linked glycoproteins and O-linked mucins within the goblet cell secretory granule.

Purification and polypeptide composition of corpora amylacea from aged human brain

Corpora amylacea (CA) accumulation in the brain is a normal correlate of ageing. The presence of a small amount of protein in these polyglucosan bodies is a consistent finding, although the nature of this protein material remains unknown. Using sucrose gradient fractionation and density centrifugation on Percoll, a method was developed to obtain highly pure preparations of CA from human brain. The protein content of isolated CA was estimated to be approx. 4% of the total fraction by weight. SDS-PAGE analysis of CA fractions showed several polypeptide bands with molecular weights ranging from 24 to 133 kDa. Four of these bands with molecular weights of 133, 94, 42 and 24 kDa are more abundant. Thus, pure preparations of CA can be obtained that are suitable for protein analysis.

L-azaserine induced preneoplasia in the rat pancreas. A morphometric study of dietary manipulation (lipotrope deficiency) and ultrastructural differentiation

Putatively preneoplastic, pancreatic atypical acinar cell foci (AACF) and nodules (AACN), collectively termed atypical acinar cell lesions (AACL), were induced in male Lewis rats by L-azaserine (300 mg/kg body weight [bw] in divided doses). Rats given carcinogen and then fed a lipotrope deficient (LD) diet developed a significantly greater number of larger lesions than animals fed complete diet throughout the experiment. It is suggested that lipotrope deficiency plays a promoting role in this model of pancreatocarcinogenesis. Ultrastructural morphometric studies of AACF, when compared to control tissues, revealed the following significant results: 1) a decrease in surface area of cell cytoplasm with no change in nuclear area, and hence increased nucleus/cytoplasm (N/C) ratio; 2) a reduction in size and uniformity of zymogen granules; and 3) an increase in number of granules per microns 2 of cell. The results suggest that arrested development of the AACF cells is associated with reduced cytoplasm and zymogen production per cell. AACL may be eosinophilic due to an overall increased concentration of zymogen in these hyperplastic lesions and not because individual acinar cells in the AACL contain an increased amount of zymogen or are "zymogen-rich," as has been reported.

Perforin mRNA in primary peritoneal exudate cytotoxic T lymphocytes

Considerable evidence indicates that cloned CTL cell lines kill target cells by releasing toxic granules that contain a cytolytic protein, called perforin, and several serine esterases (granzymes A to F). However, primary CTL, such as the highly cytolytic peritoneal exudate lymphocyte (PEL) cell population, have been found by a hemolytic assay to have no perforin, or perhaps only borderline levels of that protein, suggesting that these cells use a different lytic mechanism. To determine whether or not primary CTL express the perforin gene, we have here compared mRNA from PEL CTL and from a cloned CTL cell line, 2C, by Northern blot analysis using a perforin cDNA probe. CD8+ PEL CTL contain approximately 30% of the amount of perforin message present in 2C. Moreover, depletion of CD8+ T cells from the total peritoneal exudate cell population removes both cytolytic activity and perforin message. We have previously shown that PEL CTL elicit the same changes in target cells as cloned CTL cell lines and are resistant to lysis by the toxic granules purified from these cells lines. Taken together these results are consistent with the view that primary CTL, as well as long term cloned CTL cell lines, exercise their cytolytic activity by means of perforin.

Microvesicles of the neurohypophysis are biochemically related to small synaptic vesicles of presynaptic nerve terminals

Nerve endings of the posterior pituitary are densely populated by dense-core neurosecretory granules which are the storage sites for peptide neurohormones. In addition, they contain numerous clear microvesicles which are the same size as small synaptic vesicles of typical presynaptic nerve terminals. Several of the major proteins of small synaptic vesicles of presynaptic nerve terminals are present at high concentration in the posterior pituitary. We have now investigated the subcellular localization of such proteins. By immunogold electron microscopy carried out on bovine neurohypophysis we have found that three of these proteins, synapsin I, Protein III, and synaptophysin (protein p38) were concentrated on microvesicles but were not detectable in the membranes of neurosecretory granules. In addition, we have studied the distribution of the same proteins and of the synaptic vesicle protein p65 in subcellular fractions of bovine posterior pituitaries obtained by sucrose density centrifugation. We have found that the intrinsic membrane proteins synaptophysin and p65 had an identical distribution and were restricted to low density fractions of the gradient which contained numerous clear microvesicles with a size range the same as that of small synaptic vesicles. The peripheral membrane proteins synapsin I and Protein III exhibited a broader distribution extending into the denser part of the gradient. However, the amount of these proteins clearly declined in the fractions preceding the peak of neurosecretory granules. Our results suggest that microvesicles of the neurohypophysis are biochemically related to small synaptic vesicles of all other nerve terminals and argue against the hypothesis that such vesicles represent an endocytic byproduct of exocytosis of neurosecretory granules.

Immunocytochemical localization of cathepsins B and H in human pancreatic endocrine cells and insulinoma cells

Cathepsins B and H are representative cysteine proteinases localized to lysosomes of a variety of mammalian cells. Previous studies indicated the presence of these enzymes also in secretory granules of endocrine cells. Therefore, the human endocrine pancreas and human insulinomas were investigated by light microscopical immunohistochemistry on serial semithin plastic sections immunostained sequentially for cathepsins B or H and pancreatic hormones. Out of the four established endocrine cell types, insulin (B-) and glucagon (A-) cells showed immunoreactivities for these cathepsins. Cathepsin B immunoreactivities showed a dot-like appearance in A- and B-cells and in insulinoma cells. Immunoreactivities for cathepsin H additionally were found in cell parts containing secretory granules of B-cells and insulinoma cells. By single and double immunoelectron microscopy the dot-like immunoreactivities for cathepsin B were identified as immunoreactive lysosomes of A- and B-cells and insulinoma cells. In addition, some of the secretory granules of A- and B-cells showed cathepsin B immunoreactivities. Cathepsin H immunoreactivities showed an other pattern: they were found regularly in the secretory granules of A- and B-cells and insulinoma cells, and in lysosomes of A-cells. These findings suggest that cathepsins B and H in lysosomes of A- and/or B-cells are involved in the degradation of lysosomal constituents. In secretory granules of these cells, these cysteine proteinases may participate in the processing of the corresponding hormones from their precursor proteins.

Monocyte-chemotactic activity of defensins from human neutrophils

We investigated the monocyte-chemotactic activity of fractionated extracts of human neutrophil granules. Monocyte-chemotactic activity was found predominantly in the defensin-containing fraction of the neutrophil granules. Purified preparations of each of the three human defensins (HNP-1, HNP-2, HNP-3) were then tested. HNP-1 demonstrated significant chemotactic activity for monocytes: Peak activity was seen at HNP-1 concentrations of 5 X 10(-9) M and was 49 +/- 20% (mean +/- SE, n = 9) of that elicited by 10(-8) M FMLP. HNP-2 (peak activity at 5 X 10(-9) M) was somewhat less active, yielding 19 +/- 10% (n = 11). HNP-3 failed to demonstrate chemotactic activity. Checkerboard analysis of monocyte response to HNP-1 and HNP-2 confirmed that their activity was chemotactic rather than chemokinetic. Neutrophils demonstrated a low level of response to defensins but this reaction was primarily chemokinetic. Defensins may play a role in the recruitment of monocytes by neutrophils into inflammatory sites.

Purification and partial characterization of platelet-derived adherence-inhibiting factor in guinea pig

Purification and partial characterization of adherence-inhibiting factor (AIF) of platelet-granule fraction in guinea pig were studied. When freshly prepared platelet-granule fraction was subjected to a gel filtration, two neutrophil adherence-inhibiting peaks, designated AIF-I (2,800 kDa) and AIF-II (12 kDa), appeared. AIF-I was sensitive to diisopropylfluorophosphate (DFP) and originated from lysosomes, whereas AIF-II was insensitive to DEP and localized in alpha-granules. Both AIFs were released from platelets by a thrombin stimulation. As the total activity of AIF-I was about 5-fold higher than that of AIF-II, AIF-I was purified and characterized. When purified AIF-I was analyzed on SDS-polyacrylamide gel electrophoresis, the 340 kDa protein band and the other large protein band were observed. Under reducing condition, AIF-I was separated into three components (340, 190 and 165 kDa). AIF-I significantly inhibited neutrophil adherence to artificial substrata and to type IV collagen-coated plastic surface, but not to fibronectin- or plasma-coated plastic surfaces, suggesting that AIF-I inhibits neutrophil adherence not only via nonspecific adsorption sites but also via type IV collagen receptors.

A competition enzyme-linked immunosorbent assay (ELISA) for the measurement of pancreatic GP-2 glycoprotein

A competition enzyme-linked immunosorbent assay has been developed for the quantitative detection of soluble and membrane-bound GP-2, a glycoprotein which is confined to the exocrine pancreas. Zymogen granule membranes fixed to microtiter plates with poly-L-lysine were used as the source of antigen. Detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS] was added to the assay in order to reveal all the antigens, more particularly in membranous samples. Presence of detergent at concentrations as high as 0.5% did not interfere with any particular steps of the ELISA. This competition ELISA can detect 10 ng of GP-2 and will be useful for measuring soluble as well as membrane GP-2 in order to elucidate its role in the secretory process of the pancreas as well as in certain pathologies such as cystic fibrosis.

Quantitative analysis of phospholipids and demonstration of plasmalogen in human neutrophil subcellular fractions by high-performance liquid chromatography

The subcellular distribution of phospholipids in unstimulated neutrophils was investigated by high-performance liquid chromatography of lipid extracts of granule and plasma membranes obtained from Percoll density gradients. The mobile phase contained acetonitrile:methanol:85% phosphoric acid (131:3:0.8 v/v/v). Post-nuclear supernatants contained 2.3 micrograms lipid phosphorus/mg protein. Phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine were demonstrated in azurophil granules, specific granules and in a combined fraction of secretory granules and plasma membranes. Separate estimates of each phospholipid class by peak areas obtained by high-performance liquid chromatography showed that secretory granules and plasma membranes contained most of the phosphatidylinositol and phosphatidylcholine (p less than 0.005 vs peaks areas obtained in azurophil and specific granules), whereas a major part of the phosphatidylethanolamine was located in the specific granules (p less than 0.005 vs peak areas obtained in azurophil granules, and plasma membrane and secretory granules). High-performance liquid chromatography proved to be a useful principle for the demonstration of plasmalogen because the acidic solvent caused hydrolysis of phosphatidalethanolamine, which was recovered as lysophosphatidylethanolamine. Additionally, sphingomyelin was demonstrated in all subfractions by thin-layer chromatography.

A dense core vesicle protein is restricted to the cortex of granules in the exocrine atrial gland of Aplysia california

We have generated a monoclonal antibody (mAb) 5E10 which recognizes an antigen localized to dense core vesicles (DCVs) in the atrial gland of Aplysia californica. mAb5E10 immunoprecipitates an abundant 57-kDa glycoprotein (atrial gland granule-specific antigen, AGSA) which is a soluble component of atrial gland DCVs. Electron microscopy reveals that AGSA immunoreactivity is restricted to the region between the dense core, which contains neuropeptide immunoreactivity, and the membrane of atrial gland DCVs. AGSA was purified by immunoaffinity chromatography, and the amino acid sequences of both N-terminal and internal cyanogen bromide fragments were determined. This information was used to isolate a 2.8-kilobase cDNA which encodes a 47-kDa protein. The predicted amino acid sequence contains the micro-sequenced peptides, an N-terminal hydrophobic signal sequence, and four N-linked glycosylation sites, but does not contain any significant homologies to database sequences. Northern blots and light level immunocytochemistry demonstrate that the AGSA gene is specifically expressed in the atrial gland. The identification of a protein localized to the cortex of DCVs suggests that this region has a specialized role in the function of these vesicles.

Purification, composition, and activity of two bactenecins, antibacterial peptides of bovine neutrophils

Extracts of granules of bovine neutrophils are known to exhibit a marked antibacterial activity in vitro. By a simple, two-step chromatographic procedure, we have resolved two peptide components of the antibacterial system. They were named Bac-5 and Bac-7 from the general term bactenecin and had molecular masses of about 5 and 7 kilodaltons, respectively. Over 45 and 20% of the amino acid residues in the two bactenecins are proline and arginine, respectively. The remaining amino acids are mainly hydrophobic (isoleucine, leucine, and phenylalanine). Both Bac-5 and Bac-7 efficiently kill Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae. They also arrest the growth of Enterobacter cloacae (MICs, 25 to 200 micrograms/ml) but not of Proteus vulgaris, Staphylococcus aureus, and Streptococcus agalactiae (MIC, greater than 200 micrograms/ml). Finally, Bac-7 but not Bac-5 has MICs of less than or equal to 200 micrograms/ml for Pseudomonas aeruginosa and Staphylococcus epidermidis. From the comparison between the efficient bactericidal concentrations in vitro and the estimated content of bactenecins in neutrophils (125 ng of Bac-5 and Bac-7 each per 10(6) cells), it is reasonable to conclude that the two cationic peptides may exert a major role in host defense against at least some microorganisms.

Human eosinophil-derived neurotoxin and eosinophil protein X are likely the same protein

The human eosinophil granule contains a series of cationic proteins. Two of these, eosinophil-derived neurotoxin (EDN) and eosinophil protein X (EPX), are reported to have similar m.w. and both possess neurotoxic and helminthotoxic activities. Therefore, the properties of these molecules were analyzed to determine whether they differ. EDN was purified from eosinophils of patients with the hypereosinophilic syndrome and EPX from the buffy coat cells of normal individuals. By SDS-PAGE, both proteins showed a major band at 18.7 kDa and a minor band at 21.4 kDa. By two-dimensional non-equilibrium gel electrophoresis the proteins migrated identically. With radiolabeled proteins in reverse phase HPLC, both proteins eluted at the same concentration of acetonitrile and showed identical tryptic maps. Both proteins possessed comparable ribonuclease activity and both were comparably neurotoxic in the rabbit. By immunodiffusion the two proteins showed a reaction of identity; by RIA, with both polyclonal and monoclonal antibodies, the proteins had very similar inhibitory activities. These results indicate that EDN and EPX have virtually identical properties and are probably the same protein.

[Changes induced by simple jejuno-ileal by-pass models in the distribution of D-cells producing intestinal somatostatin. Experimental study]

Cells that produce somatostatin are widely distributed throughout the digestive tube. They are found in the stomach, small bowel, large bowel and pancreas. The authors used 54 Wistar rats, with an approximate weight of 300 gr, to evaluate the possible variations of the D cell population in isolated and functional intestinal segments, using jejuno-ileal bypass as a model. Rats were divided into three groups, a control group and two groups in which simple derivation techniques were performed following the techniques of Payne and DeWind, and Scott. Rats were sacrificed after 7, 30 and 90 days in subgroups of six animals. Macroscopic, microscopic and ultrastructural studies were carried out. Cells were specifically stained using immunocytochemical techniques (PAP). The corresponding values of the mucous areas were obtained using a computerized image analyzer (Quantimet 800) and then the number of D cells per mm2 mucosa was calculated. The results show a decrease in the number of D cells per mm2 of mucosa in the functional intestinal segments and degranulation of these cells, coinciding with the existence of large areas of rough endoplasmic reticulum (sign of cellular hyperactivity).

Analysis of human neutrophil granule protein composition in chronic myeloid leukaemia by immuno-electron microscopy

In this study immuno-electron microscopy was used to assay, semi-quantitatively, the granule contents of elastase, lactoferrin, lysozyme and myeloperoxidase in human peripheral blood neutrophils from 13 chronic myeloid leukaemia patients in the chronic phase of the disease and from normal non-smoking donors. The fixation conditions that adequately preserved the antibody binding capacities of these antigens and reasonably preserved the ultrastructure of the neutrophils were selected by light-microscopic immunoperoxidase cytochemistry on cytospin smears. Immunogold cytochemistry on LR White resin sections localised elastase and myeloperoxidase to the primary granules, lactoferrin to the secondary granules and lysozyme to both types of granule. When applicable, peroxidase cytochemistry was combined with immunogold staining making it easier to distinguish the primary from the secondary granules. A comparison of the immunolabelling density values obtained for the leukaemic and normal states revealed no significant abnormalities in the immunoreactivity patterns for any of these neutrophil granule antigens in the leukaemic patients. All 13 patients gave normal immunostaining reactivities for these neutrophil granule proteins. Consequently the distribution patterns of these proteins, as shown in this study, cannot be used as indices in distinguishing chronic myeloid leukaemic neutrophils from normal neutrophils.

Studies on two major contaminating proteins of the cytoplasmic inclusion bodies in Escherichia coli

Two major contaminating proteins of the cytoplasmic inclusion bodies in recombinant Escherichia coli overexpressing a LacZ-papain fusion protein were studied. The proteins were isolated and their amino acid composition and N-terminal sequence analyses were performed. The N-terminal sequence of these proteins were then compared with the sequence of E. coli proteins available in the data bank. The sequences of the contaminating proteins matched with the outer membrane protein II and outer membrane protein F of E. coli.