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F Shanahan

Publications and source records attributed to F Shanahan.

At least 217 records · Page 12Linked to original sources
PubMed1988

Hermansky-Pudlak syndrome: an immunologic assessment of 15 cases.

PURPOSE: The Hermansky-Pudlak syndrome is an autosomal recessive disorder consisting of the triad of oculocutaneous albinism, a storage pool platelet defect, and multisystem tissue deposition of ceroid pigment. Although the underlying metabolic defect has not been identified, secondary or associated effects on the immune system are suggested by reports of an association with disorders such as pulmonary fibrosis, granulomatous colitis, lupus, and frequent bacterial infections. We evaluated a large group of patients with the Hermansky-Pudlak syndrome to assess immune competence in this condition. PATIENTS AND METHODS: Fifteen patients with this syndrome were studied. Control subjects included healthy volunteers in the same age range as the patients. Peripheral blood lymphocytes and neutrophils were isolated according to previously described methods. Immunofluorescent staining, flow cytometry, and cytotoxicity assays were performed. Determination of lymphocyte transformation, mixed lymphocyte response, and neutrophil function was made. RESULTS: Immunoglobulin levels, complement, lymphocyte subsets, natural killer and lymphokine-activated cytotoxicity, mixed lymphocyte responses, and lectin-induced transformation were normal in all patients. In addition, there was no evidence for a lymphocyte proliferative response to a preparation of urinary ceroid pigment isolated from these patients. Neutrophil function, including luminol-dependent chemiluminescence, chemotaxis, and aggregation was not significantly different from control values. CONCLUSION: The results suggest that there is no generalized defect of peripheral blood lymphocyte or neutrophil function in the Hermansky-Pudlak syndrome. We propose that future studies should examine the possibility that associated disorders arise from a defect within the monocyte-macrophage system, perhaps secondary to ceroid accumulation.

Adolescent↗
PubMed1988

Modulation of histamine release from canine fundic mucosal mast cells.

To study the control of histamine release, we developed techniques for culturing fundic mucosal mast cells. After enzyme dispersion, enrichment by elutriation, and overnight suspension culture, mast cells accounted for 30% of the cells present. Histamine release into the medium, measured by radioenzymatic assay, was stimulated by the lectin concanavalin A (Con A). Ragweed antigen released histamine in antisera-sensitized cultures. Con A-induced histamine release was enhanced by adenosine, but adenosine alone was inactive. The relative potency of adenosine analogues was consistent with interaction at an adenosine A1-receptor site. The calcium ionophore A23187 (0.1-1 microM) also induced histamine release. Phorbol esters that activate protein kinase C, such as phorbol 12-myristate 13-acetate, did not release histamine but enhanced release when added to low concentrations of A23187. In contrast, inactive phorbols, such as 4 alpha-phorbol 12,13-didecanoate, failed to enhance A23187-induced release. Parallel studies with canine hepatic mast cells yielded comparable results. We conclude that canine fundic mast cells possess receptors for immunoglobulin E and adenosine. Our data are consistent with increases in cytosolic calcium and protein kinase C activation working synergistically to stimulate fundic mast cells.

Adenosine↗
PubMed1987

Modulation of ongoing human immunoglobulin synthesis by natural killer cells.

Freshly separated human NK cells (NKH-1+) inhibited IgE synthesis from IgE myeloma U266/AF-10 as much as 70% whereas they enhanced IgG and IgA synthesis 200 and 500% from the lymphoblastoid cell lines GM-1500 and GM-1056, respectively. The inhibition of IgE synthesis by NK cells was due to a direct cytolytic effect on AF-10. This could be reversed using K562 cells in a cold target competition assay. NK cells also inhibited spontaneous IgE as well as IgG and IgA synthesis from B cells of highly atopic donors. On the other hand the enhancement of Ig secretion by NKH-1+ cells was shown to be mediated by soluble factors released from NK cells. Furthermore when NK cells were preincubated with immune complexes (IgE-IC) constructed of human IgE and mouse IgG1 monoclonal anti-human IgE, inhibition of IgE synthesis was reversed, and in some cases actual enhancement of IgE synthesis was observed, while enhancement of IgG and IgA synthesis was not affected. In contrast to NK cells, T cells depleted of NK cells (T-NK), when activated by IgE-IC, suppressed IgE synthesis in an isotype specific fashion. Thus, NK and T-cell modulation of ongoing Ig synthesis involve distinct mechanisms.

Antibody Formation↗
PubMed1987

Human mucosal cytotoxic effector cells.

Human intestinal lamina propria mononuclear cells have been shown to mediate mitogen-induced cellular cytotoxicity, antibody-dependent cellular cytotoxicity, and lymphokine activated killer cell function. However, although natural killer cells have been demonstrated in the gut mucosa of rodents, recent reports found little or no spontaneous cytotoxic activity in the lamina propria of the human gut. Using the natural killer cell-related monoclonal antibody NKH-1, which has not previously been applied to studies of mucosal killer cell function, we have shown by immunofluorescence that 2%-3% of enzymatically dispersed lamina propria lymphocytes are NKH-1+. A "panning" technique was then used to enrich for the NKH-1+ cells. Panned cells were consistently greater than or equal to 80% NKH-1+ by indirect immunofluorescence. Unlike their counterparts in the peripheral blood, the mucosal NKH-1+ cells were Leu-11-. Although unseparated lamina propria lymphocytes failed to exhibit natural killer activity against K562 targets in 4-h chromium release assays at effector to target ratios of up to 100:1, the NKH-1+ cells were cytolytically active at ratios of less than 5:1. Mucosal lymphocytes depleted of natural killer cells (NKH-1-) exhibited cytotoxic activity when cultured for 72 h with interleukin-2. The precursors of the lymphokine culture activated phenomenon were NKH-1-, Leu-11-, T4-, T3-, T11+, and T8+. Although lamina propria T3+ cells did not exhibit spontaneous or culture activated cytotoxicity, they were shown to exhibit nonspecific anti-CD3 (anti-T3)-induced T-cell cytotoxicity. In conclusion, functional natural killer and lymphokine activated killer cells are both present in the human gut mucosa and represent distinct populations of cytotoxic cells. In addition, anti-CD3-induced cytotoxicity is a feature of mucosal T cells. These mucosal killer cell subsets differ phenotypically from those previously described in the peripheral blood.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Human lung mast cells: distribution and abundance of histochemically distinct subpopulations.

Methods originally employed to demonstrate the heterogeneity of mast cells in the rat and more recently in the human intestine were used to study mast cell heterogeneity in the human bronchial mucosa and lung parenchyma. Thus, a quantitative survey of pulmonary mast cells using different fixation and staining procedures indicated that two distinct mast cell subpopulations (formalin-sensitive and formalin-resistant) are present and have distinct patterns of distribution and abundance. The findings are of potential clinical importance because histochemical heterogeneity may be a marker of functional mast cell differences in humans including differences in responsiveness to antiallergic drugs, as occurs in rats. The findings also indicate that conventional methods of fixation are likely to lead to a gross underestimation of total mast cell numbers.

Bronchi↗
PubMed1987

Immunologic mechanisms in intestinal diseases.

The intestine is a unique immunologic organ that comprises an afferent and efferent compartment and provides the host with the ability to respond through several different effector mechanisms against environmental factors. We discuss mechanisms in three intestinal diseases in this overview of the mucosal immune system. Genetic and immunologic factors are important in the pathogenesis of celiac disease, which is characterized by damage to the mucosa of the small intestine with resultant malabsorption. Pathogenic microbes are important environmental agents that interact with the intestinal mucosa and initiate local immune responses. Advances in the understanding of the mucosal immune response to these pathogenic microbes have produced a clear picture of the way in which this specialized immune system works in concert with systemic immunity. As to the autoimmune nature of inflammatory bowel disease, no specific antigen has been shown to incite the inflammatory reactions and neither the target cells nor the effector mechanism involved have been identified. Several factors exist, however, to suggest an autoimmune mechanism and the role of mucosal immunologic factors in this disease.

Autoimmune Diseases↗
PubMed1987

Defective memory B cell formation in patients with inflammatory bowel disease following tetanus toxoid booster immunization.

Inflammatory bowel disease patients with mild to inactive disease were studied for their ability to generate pokeweed mitogen responsive anti-tetanus toxoid IgG producing B cells in the peripheral blood 21 days following in vivo tetanus toxoid booster immunization. Compared to normals and disease controls, patients with inflammatory bowel disease had significantly impaired in vitro production of anti-tetanus toxoid antibody during an 8 day pokeweed mitogen stimulated culture period. There was poor correlation between the ratio of helper to suppressor T cells in the peripheral blood and pokeweed mitogen stimulated antibody production. Likewise, there was little correlation between in vitro antibody production and peripheral blood natural killer cell cytotoxic activity. Culture of the patients B cells with normal T cells failed to improve antibody production in vitro. These results indicate that many inflammatory bowel disease patients have an impaired humoral immune response to tetanus toxoid booster immunization. This impaired immune response may be due to an inability to generate B cell precursors of anti-tetanus toxoid IgG producing B cells rather than to abnormal circulating helper or suppressor T cell activity or natural killer cell regulatory activity.

Adult↗
PubMed1986

K562 killing by K, IL 2-responsive NK, and T cells involves different effector cell post-binding trigger mechanisms.

The monoclonal antibody 13.3 specifically blocks the trigger process of the NK-K562 cytolytic sequence at a post-binding effector cell level. This antibody was used to define differences in the lytic trigger processes of NK and other mechanisms of K562 lysis. Monoclonal antibody 13.3 inhibited lysis of K562 target cells by freshly isolated peripheral blood lymphocytes (PBL) and purified large granular lymphocytes (LGL), but had no inhibitory effect on antibody-dependent cell-mediated cytotoxicity to K562 by these effectors. Lectin-dependent cellular cytotoxicity (LDCC) to this target cell was also unresponsive to 13.3. The 13.3-induced inhibition of NK-K562 lytic activity persisted when PBL were activated in culture with interleukin 2 (IL 2) for periods up to 48 hr. After 48 hr of culture, the degree of inhibition diminished progressively in medium containing fetal calf serum but not in medium containing autologous serum. This 13.3-unresponsive lytic activity in cultured PBL could be attributed to more than one cell type and was present in both the LGL and Fc gamma receptor-depleted T cell fraction. Thus, K562 lysis by freshly isolated human lymphocytes via NK, K, and LDCC mechanisms is characterized by heterogeneity of the post-binding effector cell trigger mechanism. K562 lysis by lymphocytes cultured with IL 2 is similarly heterogeneous.

Antibodies, Monoclonal↗
PubMed1986

Inhibition of cytotoxicity by sulfasalazine. II. Sulfasalazine and sulfapyridine inhibit different stages of the NK and NKCF lytic processes.

Sulfasalazine and sulfapyridine but not 5-aminosalicylate inhibit spontaneous cytotoxicity mediated by human natural killer (NK) cells. The aim of this study was to determine which stage(s) of the NK cytotoxic reaction is inhibited by these compounds. Effector/target cell binding studies performed in parallel with cytotoxicity assays using purified large granular lymphocytes indicated that inhibition is a post-binding event. The kinetic profile of inhibition in a calcium pulse assay showed that inhibition continues long after the effector cell triggering stage and that although sulfasalazine may have some inhibitory effect on the calcium-dependent events of the programming phase, sulfapyridine continues to inhibit during the calcium-independent or lethal hit phase of the cytotoxic sequence. The NK soluble cytotoxic factor (NKCF) assay was used as a measure of the lethal hit since the time course of this assay permits study of the various substages of this terminal event in the lytic sequence. Sulfasalazine and sulfapyridine but not 5-aminosalicylate inhibited NKCF-mediated target cell lysis. Different substages of the NKCF-induced lytic reaction were affected by these agents. Sulfasalazine appears to inhibit binding of NKCF to the target cell whereas sulfapyridine predominantly inhibits early post-binding events.

Aminosalicylic Acids↗
PubMed1986

Mast cell heterogeneity: effect of anti-allergic compounds on neuropeptide-induced histamine release.

Increasing evidence suggests that neuropeptides may be important stimuli for mast cell secretion. Neuropeptide-induced histamine secretion from rat mast cells was inhibited by a variety of clinical and experimental antiallergic agents. The profile of responsiveness to this panel of drugs exhibited by peritoneal (PMC) and intestinal mucosal mast cells (IMC) was similar to that previously reported when histamine release was immunologically induced. Thus, cromoglycate, theophylline and Ro 22-3747 inhibited peptide-induced secretion from PMC but not from IMC. In contrast, doxantrazole was effective against PMC and IMC. Differences between IMC and PMC could not be attributed to the IMC isolation procedure. The results confirm the heterogeneity of responsiveness to antiallergic drugs exhibited by these mast cell subpopulations and indicate that it is not limited to immunologically induced secretion but also occurs when a neuropeptide is the secretory stimulus.

Animals↗
PubMed1986

Functional characterization of mast cells generated in vitro from the mesenteric lymph node of rats infected with Nippostrongylus brasiliensis.

We have examined the biochemical and functional characteristics of mast cells grown in tissue culture from the mesenteric lymph node (MLN) of rats infected with the nematode Nippostrongylus brasiliensis and compared them with mast cells isolated from the small intestinal mucosa and peritoneal cavity of infected animals. Cultured mast cells (MC) and isolated intestinal mucosal mast cells (MMC) had a similar histamine content, and both contained type II protease (RMCP II) which was absent from peritoneal mast cells (PMC). PMC, MMC and cultured MC each responded to immunologically induced histamine secretion, but MMC and cultured MC were hyporesponsive to calcium ionophores and unresponsive to widely used PMC secretagogues including compound 48/80 and bee venom peptide 401. MMC and cultured MC also differed from PMC in their lack of responsiveness to the anti-allergic agent disodium cromoglycate. Thus, MC cultured from the MLN are distinct from PMC but have a biochemical and functional phenotype similar to that of intestinal MMC.

Animals↗
PubMed1985

Mast cell heterogeneity: effects of neuroenteric peptides on histamine release.

Recent reports suggesting that the actions of certain neuroenteric peptides may be mediated in part by the secretion of histamine and other mast cell contents could have important implications for gastrointestinal motility and secretion. However, evidence for a mast cell-hormonal interaction is based on studies using peritoneal or cutaneous mast cells. Because intestinal mucosal mast cells (MMC) differ functionally from peritoneal mast cells (PMC), we compared the effects of several neurotransmitters and intestinal hormones on histamine secretion from two mast cell types in the rat. MMC hyperplasia was induced in rats by infection with the nematode Nippostrongylus brasiliensis, and MMC were isolated from the small intestine by collagenase digestion. Substance P, somatostatin, vasoactive intestinal polypeptide (VIP), neurotensin, and bradykinin had a potent secretagogue effect on (10(-7) to 10(-4)M) PMC which was temperature-, energy-, and calcium-dependent. In contrast to PMC, MMC released significant amounts of histamine only when challenged with substance P. Acetylcholine, bombesin, motilin, and pentagastrin had no secretory effect on either PMC or MMC. The differences between PMC and MMC in responsiveness to peptides could not be attributed to the MMC isolation procedure because PMC treated similarly or mixed with MMC suspensions retained their responsiveness to these stimuli. Our results extend the concept of neurocrine control of mast cell function, but indicate that mast cells from different sites have distinct profiles of responsiveness to regulatory peptides.

Animals↗
PubMed1985

Intestinal mucosal mast cells: isolation from rat lamina propria and purification using unit gravity velocity sedimentation.

Mucosal mast cell (MMC) suspensions obtained from the rat intestinal lamina propria by collagenase digestion (35.2 +/- 3.2% MMC) were enriched to 65.5 +/- 5.2% MMC by the use of a discontinuous gradient (30%/80%) of Percoll. Further purification to 95.7 +/- 1.3% MMC was achieved using velocity sedimentation at unit gravity (Sta-Put). Analysis of the cells throughout the purification procedure confirms that the purified MMC are representative of the MMC in the initial isolated cell suspension. No differences were seen in terms of size, histamine content, protease content and responsiveness to secretagogues among the initial isolated population, the Percoll-enriched population and the Sta-Put-purified population. This study represents a major advance in mast cell research in that, for the first time, mast cells isolated from a homogeneous in vivo mucosal source have been obtained at levels of purity sufficient for specific biochemical characterization. Such characterization will aid in the interpretation of the role of MMC in disease and will provide a firm basis of knowledge of the form and function of intestinal MMC for comparison with mast cells derived from other mucosal sites or cultured in vitro from various organs.

Animals↗