Exocytosis is a vital function of many cell types including neuron, endocrine cell and immunocyte. Secretion in immunocytes involves a complex process of signal transduction, in which many factors still remain unknown. In the last 10 years, this area has become an international hot spot of investigation, resulting in many break-through progresses. This progress was made possible by combined efforts in molecular biology, cell biology and biophysics. This review focuses on notable new knowledge and some new techniques in functional study of secretion in immunocytes.
Exocytosis ; physiology ; Humans ; Ion Channels ; physiology ; Lymphocytes ; immunology ; secretion ; Mast Cells ; immunology ; secretion ; Membrane Proteins ; physiology ; Neutrophils ; immunology ; secretion ; SNARE Proteins ; Signal Transduction ; physiology ; Vesicular Transport Proteins

AIMTo examine the ability of calcium ionophore (CI) to induce tryptase and histamine release from human mast cells and its mechanisms.

METHODSEnzymatically dispersed cells from human colons were challenged with CI, and the cell supernatants after challenge were collected. Tryptase release was determined with a sandwich ELISA procedure and histamine release was measured using a glass fibre-based fluorometric assay.

RESULTSCI was able to induce a concentration dependent release of histamine and tryptase from human colon mast cells following 15 min incubation. The maximum of induced histamine and tryptase release were approximately 5.3 and 2.8 fold more than the levels of spontaneous release, respectively. CI at the concentrations higher than 1.0 micromol/L was able to induce significantly more histamine than tryptase release from mast cells. The time course revealed that the action of CI on mast cells started from 10 s, peaked at 6 min and lasted at least 15 min following incubation. Pertussis toxin and metabolic inhibitors were able to inhibit mast cell response to CI.

CONCLUSIONHuman colon mast cells were able to release tryptase and histamine in response to CI. The process seemed to be associated with the activation of a G-protein coupled receptor on the membrane of mast cells and requires cell energy supply.

Calcium Ionophores ; pharmacology ; Cells, Cultured ; Colon ; cytology ; Histamine ; metabolism ; Humans ; Mast Cells ; drug effects ; metabolism ; secretion ; Tryptases ; metabolism

OBJECTIVETo investigate the role of mast cells and gut hormones and their interactions in TNBS-induced ulcerative colitis.

METHODSRat models of ulcerative colitis were established by a single intracolonic injection of 100 mg/kg TNBS (in 0.3 ml 50% ethanol). At 0, 6, 11, 16, 21 days after TNBS injection, the rats were sacrificed to determine the count of the mast cells. Histamine level in the whole blood, and the levels of histamine, substance P (SP), vasoactive intestinal peptide (VIP), and somatostatin (SS) in the distal colons were measured by fluorimetry or radioimmune assay. Immunofluorescence double staining was used to observe the relationship of the mast cells with SP, VIP, and SS positive nerve fibers.

RESULTSOn day 6 after TNBS injection, obvious ulcers occurred in the distal colon of the rats with significantly increased histamine level in the whole blood (P<0.05) but significantly decreased colonic histamine levels (P<0.05). The histamine levels in the whole blood and distal colon gradually recovered the normal levels. The mast cells significantly increased on day 16 (P<0.05) and maintained the high level till day 21. The distribution of mast cells was altered after TNBS injection, and the cells were found to aggregate in the myenteric region. SP levels in the distal colon significantly increased on day 11 (P<0.05) and maintained the high level till day 21. Immunofluorescence double staining revealed numerous mast cells close to the SP- and VIP-positive nerve fibers at different time points after TNBS injection. VIP positivity and the number of VIP-positive nerve fibers in the myenteric region were markedly increased, but no mast cells were observed in association with SP- and VIP-positive nerve fibers. The distribution of MC was not found to associate with the SS-positive nerve fibers.

CONCLUSIONThe mast cells and histamine released by them, as well as parasecretion of SP and VIP, participate in tissue damage by TNBS-induced colitis. Bidirectional neuroimmunomodulation of the mast cells, SP and VIP have important effect on the development of TNBS-induced colitis.

Animals ; Colitis, Ulcerative ; chemically induced ; metabolism ; pathology ; Disease Models, Animal ; Male ; Mast Cells ; secretion ; Rats ; Rats, Sprague-Dawley ; Substance P ; metabolism ; Trinitrobenzenesulfonic Acid ; toxicity ; Vasoactive Intestinal Peptide ; metabolism

OBJECTIVETo provide evidences for evaluating the role of chlorogenic acid (CA) on the adverse reaction of traditional Chinese medicine injection and promoting clinical rational usage of CA, the effect of CA and chlorogenic acid-HSA(CA-HSA) on the degranulation in mast cell RBL-2H3 were compared and the allergenic effect and its mechanism were investigated.

METHODThe unsensitized and sensitized RBL-2H3 cells were used. The releasing rate of histamine and beta-hexosaminidase was detected by colormetric assays. The degranulating rate was detected by neutral red staining and Annexin V positive cell rate was detected by flow cytometry.

RESULTCA and CA-HSA could not induce degranulation in unsensitized RBL-2H3 cells. CA and CA-HSA could significantly increase the release of histamine and beta-hexosaminidase, degranulating rate and Annexin V positive cell rate.

CONCLUSIONCA has strong allergenicity after combination with serum proteins. As an active ingredient of Shuanghuanglian injection, CA is a kind of possible allergen which caused hypersensitivity reactions induced by Shuanghuanglian injection.

Animals ; Cell Degranulation ; drug effects ; Cell Line ; Chlorogenic Acid ; adverse effects ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; adverse effects ; Histamine Release ; drug effects ; Mast Cells ; cytology ; drug effects ; secretion ; Rats ; beta-N-Acetylhexosaminidases ; secretion

To investigate the pathogenic mechanism of late asthmatic response in comparison to early asthmatic response, changes of serum neutrophil chemotactic activity (NCA) using the Boyden chamber method and histamine level using the automated fluorometric analyzer were observed in 13 aspirin (ASA)-sensitive asthma subjects (group I: 7 early responders and group II: 6 dual responders) during lysine aspirin bronch-oprovocation test (L-ASA BPT). Sera were collected before, and 30 min and 240 min after L-ASA BPT. Serum NCA increased significantly after 30 min (p=0.02) and decreased significantly at 240 min (p=0.02) in group I, while serum NCA of group II increased significantly at 30 min (p=0.04), tending to increase further up to 240 min with no statistical significance. NCA at 240 min in group II subjects was significantly higher than baseline NCA (p=0.02). The serum NCAs collected before and 240 min were significantly higher in group II than in group I (p<0.05, respectively). There were no significant changes in serum histamine levels during L-ASA BPT in both groups. NCA derived from mast cell may contribute to the development of early asthmatic response induced by L-ASA inhalation. There may be a possible involvement of NCA derived from mononuclear cells during late asthmatic response.
Adult ; Aged ; Aspirin/adverse effects ; Aspirin/diagnostic use* ; Asthma/blood* ; Asthma/chemically induced ; Bronchial Provocation Tests* ; Chemotactic Factors/blood* ; Chemotactic Factors/secretion ; Chemotaxis/drug effects* ; Comparative Study ; Female ; Histamine/blood ; Human ; Interleukin-8/antagonists & inhibitors ; Interleukin-8/physiology ; Lysine/diagnostic use* ; Male ; Mast Cells/secretion ; Methacholine Chloride/diagnostic use ; Middle Aged ; Monocytes/secretion ; Neutrophils/drug effects* ; Time Factors

The inhibitory effect of cromakalim on the mediator release from mast cells caused by antigenantibody reactions was in controversy with the specific antigen used. However, it has recently been observed that cromakalim inhibits the release of mediators from superfused tracheal and parenchymal strips or lung mast cells after passive sensitization with the IgG1 antibody. An attempt, therefore, was made to determine the inhibitory mechanisms of cromakalim on the release of mediators such as histamine and leukotriene released by the activation of enzymes during mast cell activation. Guinea pig lung mast cells were purified through enzyme digestion, rough percoll and continuous percoll density gradients. The purified mast cells were prelabeled with [3H]palmitic acid. PLD activity was assessed more directly by the production of labeled phosphatidylethanol by PLD-mediated transphosphatidylation in the presence of ethanol. In the cells labelled with [3H]myristic acid, [3H] DAG production was measured. The methyltransferase activity was assessed by measuring the incorporation of [3H]methyl moiety into phospholipids in sensitized mast cells labelled with L-[3H] methylmethionine. cAMP level was measured by radioimmunoassay. Cromakalim resulted in a decrease in the amount of histamine and leukotrienes releases by 30% in the ovalumin-induced mast cell. Cromakalim had little effect on phospholipase D activity enhanced by the activated mast cell. Cromakalim inhibited the initial increase of diacylglycerol production during mast cell activations. Cromakalim inhibited the phospholipid methylation increased in the activated mast cell. These results show that cromakalim decreases histamine release by inhibiting the initial increase of 1,2-diacylglycerol during the mast cell activation, which is mediated via the phosphatidylinositide-phospholipase C system rather than the phosphatidylcholine-phospholipase D system. Furthermore, cromakalim reduces phosphatidylcholine production by inhibiting the methyltransferase, which decreases the conversion of phosphatidylcholine into arachidonic acid and inhibits the production of leukotrienes.
Adenylate Cyclase/metabolism ; Animal ; *Antigen-Antibody Reactions ; Benzopyrans/*pharmacology ; Cromakalim ; Diglycerides/biosynthesis ; Female ; Guinea Pigs ; Histamine Release/*drug effects ; Leukotrienes/*secretion ; Lung/drug effects/secretion ; Mast Cells/*drug effects/secretion ; Methylation ; Phospholipase D/metabolism ; Phospholipids/metabolism ; Potassium Channels/*drug effects ; Pyrroles/*pharmacology ; Support, Non-U.S. Gov't

The inhibitory effect of cromakalim on the mediator release from mast cells caused by antigenantibody reactions was in controversy with the specific antigen used. However, it has recently been observed that cromakalim inhibits the release of mediators from superfused tracheal and parenchymal strips or lung mast cells after passive sensitization with the IgG1 antibody. An attempt, therefore, was made to determine the inhibitory mechanisms of cromakalim on the release of mediators such as histamine and leukotriene released by the activation of enzymes during mast cell activation. Guinea pig lung mast cells were purified through enzyme digestion, rough percoll and continuous percoll density gradients. The purified mast cells were prelabeled with [3H]palmitic acid. PLD activity was assessed more directly by the production of labeled phosphatidylethanol by PLD-mediated transphosphatidylation in the presence of ethanol. In the cells labelled with [3H]myristic acid, [3H] DAG production was measured. The methyltransferase activity was assessed by measuring the incorporation of [3H]methyl moiety into phospholipids in sensitized mast cells labelled with L-[3H] methylmethionine. cAMP level was measured by radioimmunoassay. Cromakalim resulted in a decrease in the amount of histamine and leukotrienes releases by 30% in the ovalumin-induced mast cell. Cromakalim had little effect on phospholipase D activity enhanced by the activated mast cell. Cromakalim inhibited the initial increase of diacylglycerol production during mast cell activations. Cromakalim inhibited the phospholipid methylation increased in the activated mast cell. These results show that cromakalim decreases histamine release by inhibiting the initial increase of 1,2-diacylglycerol during the mast cell activation, which is mediated via the phosphatidylinositide-phospholipase C system rather than the phosphatidylcholine-phospholipase D system. Furthermore, cromakalim reduces phosphatidylcholine production by inhibiting the methyltransferase, which decreases the conversion of phosphatidylcholine into arachidonic acid and inhibits the production of leukotrienes.
Adenylate Cyclase/metabolism ; Animal ; *Antigen-Antibody Reactions ; Benzopyrans/*pharmacology ; Cromakalim ; Diglycerides/biosynthesis ; Female ; Guinea Pigs ; Histamine Release/*drug effects ; Leukotrienes/*secretion ; Lung/drug effects/secretion ; Mast Cells/*drug effects/secretion ; Methylation ; Phospholipase D/metabolism ; Phospholipids/metabolism ; Potassium Channels/*drug effects ; Pyrroles/*pharmacology ; Support, Non-U.S. Gov't

OBJECTIVECheongseoikki-tang (CIT, Korean), also called Qingshu Yiqi decoction () and Seisho-ekki-to (Japanese), is well known as an effective traditional combination of herbs for treating cardiovascular diseases. This study was to research its effects on bone marrow-derived mast cell (BMMC)-mediated allergy and inflammation mechanisms.

METHODSIn this study, the biological effect of Cheongseoikki-tang ethanol extract (CITE) was evaluated, focusing on its effects on the production of allergic mediators by phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187 (A23187)-stimulated BMMCs. These allergic mediators included interleukin-6 (IL-6), prostaglandin D2 (PGD2), leukotriene C4 (LTC4), and β-hexosaminidase (β-hex).

RESULTSOur data revealed that CITE inhibited the production of IL-6, PGD2, LTC4, and β-hex induced by PMA plus A23187 (P<0.05).

CONCLUSIONThese findings indicate that CITE has the potential for use in the treatment of allergy.

Animals ; Anti-Inflammatory Agents ; pharmacology ; therapeutic use ; Bone Marrow Cells ; pathology ; Calcimycin ; pharmacology ; Cell Degranulation ; drug effects ; Cell Survival ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Hypersensitivity ; drug therapy ; pathology ; Interleukin-6 ; secretion ; Leukotriene C4 ; pharmacology ; Male ; Mast Cells ; drug effects ; pathology ; physiology ; Mice ; Mice, Inbred BALB C ; Prostaglandin D2 ; biosynthesis ; Tetradecanoylphorbol Acetate ; pharmacology ; beta-N-Acetylhexosaminidases ; metabolism