Monocyte-mediated antibody-dependent cellular cytotoxicity: a clinical test of monocyte function.
The lack of a simple, rapid, and quantitative test of the functional activity of the monocyte has hampered studies of the contribution of this cell type to host defense and human disease. This report describes an assay of antibody-dependent cellular cytotoxicity, which depends exclusively upon the monocyte as the effector cell and therefore provides a convenient test of monocyte function. In this system, mononuclear leukocytes (MNL) obtained by Ficoll-Hypaque separation of whole blood are cytotoxic for 51Cr-labeled human erythrocyte targets coated with anti-blood group antibody. Removal of phagocytic monocytes from the MNL by iron ingestion, followed by exposure to a magnetic field, completely abolishes all cytotoxic activity from the remaining MNL population. Similarly, in severely mono-cytopenic patients with aplastic anemia, cytotoxic effector activity is absent. In normals and less severely monocytopenic aplastic anemia patients, cytotoxicity correlates significantly (p less than 0.001) with monocyte number. Application of this monocyte-mediated antibody-dependent cellular cytotoxicity assay to the study of patients with the Wiskott-Aldrich syndrome has revealed defective monocyte cytotoxic activity in spite of normal monocyte numbers, suggesting that this test may be useful for the assessment of monocyte function in a variety of clinical situations. (+info)
Possible suppression of host resistance by estrogen therapy for prostatic cancer.(2/7321)
Cell-mediated immunity: dealing a direct blow to pathogens.
Cytotoxic T lymphocytes are essential for defence against viral infections. Recent data demonstrating direct killing of intracellular bacteria by granulysin, a protein released from the granules of cytotoxic T lymphocytes, emphasize the contribution of these lymphocytes to the control of tuberculosis. (+info)
Antitumor effect of allogenic fibroblasts engineered to express Fas ligand (FasL).
Fas ligand is a type II transmembrane protein which can induce apoptosis in Fas-expressing cells. Recent reports indicate that expression of FasL in transplanted cells may cause graft rejection and, on the other hand, tumor cells may lose their tumorigenicity when they are engineered to express FasL. These effects could be related to recruitment of neutrophils by FasL with activation of their cytotoxic machinery. In this study we investigated the antitumor effect of allogenic fibroblasts engineered to express FasL. Fibroblasts engineered to express FasL (PA317/FasL) did not exert toxic effects on transformed liver cell line (BNL) or colon cancer cell line (CT26) in vitro, but they could abrogate their tumorigenicity in vivo. Histological examination of the site of implantation of BNL cells mixed with PA317/FasL revealed massive infiltration of polymorphonuclear neutrophils and mononuclear cells. A specific immune protective effect was observed in animals primed with a mixture of BNL or CT26 and PA317/FasL cells. Rechallenge with tumor cells 14 or 100 days after priming resulted in protection of 100 or 50% of animals, respectively. This protective effect was due to CD8+ cells since depletion of CD8+ led to tumor formation. In addition, treatment of pre-established BNL tumors with a subcutaneous injection of BNL and PA317/FasL cell mixture at a distant site caused significant inhibition of tumor growth. These data demonstrate that allogenic cells engineered with FasL are able to abolish tumor growth and induce specific protective immunity when they are mixed with neoplastic cells. (+info)
Giardia induces proliferation and interferon gamma production by intestinal lymphocytes.
BACKGROUND: Murine intraepithelial lymphocytes kill Giardia lambia; responses of human intestinal lymphocytes to this parasite are unknown. AIMS: To examine giardia induced proliferation, interferon gamma production, migration, and cytotoxicity by lymphocytes from the human intestine and peripheral blood. METHODS: Giardia were added to intraepithelial lymphocytes, lamina propria lymphocytes, and peripheral blood lymphocytes, obtained from jejunal mucosa and blood of otherwise healthy patients undergoing gastric bypass surgery for morbid obesity. Proliferation was measured by 3H-thymidine incorporation; frequency of proliferation precursors, by limiting dilution analysis; interferon gamma production, by ELISA; cytotoxicity, by 51Cr release of radiolabelled giardia and by release of serine esterases by effector lymphocytes that mediate cytotoxicity. RESULTS: The CD4+ T lymphocytes from intestine and blood proliferated in response to giardia. The stimulus by the parasite was mitogenic rather than antigenic due to the fact that the peak response was on day 3 rather than day 6, and the large number of precursors was in the range of that for mitogens. CD4+ T lymphocytes from both sites produced interferon gamma in response to giardia. Lymphocytes did not migrate towards or kill the parasite. CONCLUSIONS: Giardia induced the same degree of proliferation and interferon gamma production by CD4+ T lymphocytes in intestine and blood, but did not trigger cytotoxicity or migration. (+info)
From myocarditis to cardiomyopathy: mechanisms of inflammation and cell death: learning from the past for the future.
A progression from viral myocarditis to dilated cardiomyopathy has long been hypothesized, but the actual extent of this progression has been uncertain. However, a causal link between viral myocarditis and dilated cardiomyopathy has become more evident than before with the tremendous developments in the molecular analyses of autopsy and endomyocardial biopsy specimens, new techniques of viral gene amplification, and modern immunology. The persistence of viral RNA in the myocardium beyond 90 days after inoculation, confirmed by the method of polymerase chain reaction, has given us new insights into the pathogenesis of dilated cardiomyopathy. Moreover, new knowledge of T-cell-mediated immune responses in murine viral myocarditis has contributed a great deal to the understanding of the mechanisms of ongoing disease processes. Apoptotic cell death may provide the third concept to explain the pathogenesis of dilated cardiomyopathy, in addition to persistent viral RNA in the heart tissue and an immune system-mediated mechanism. Beneficial effects of alpha1-adrenergic blocking agents, carteolol, verapamil, and ACE inhibitors have been shown clinically and experimentally in the treatment of viral myocarditis and dilated cardiomyopathy. Antiviral agents should be more extensively investigated for clinical use. The rather discouraging results obtained to date with immunosuppressive agents in the treatment of viral myocarditis indicated the importance of sparing neutralizing antibody production, which may be controlled by B cells, and raised the possibility of promising developments in immunomodulating therapy. (+info)
Norepinephrine, released from sympathetic neurons, and epinephrine, released from the adrenal medulla, participate in a number of physiological processes including those that facilitate adaptation to stressful conditions. The thymus, spleen, and lymph nodes are richly innervated by the sympathetic nervous system, and catecholamines are thought to modulate the immune response. However, the importance of this modulatory role in vivo remains uncertain. We addressed this question genetically by using mice that lack dopamine beta-hydroxylase (dbh-/- mice). dbh-/- mice cannot produce norepinephrine or epinephrine, but produce dopamine instead. When housed in specific pathogen-free conditions, dbh-/- mice had normal numbers of blood leukocytes, and normal T and B cell development and in vitro function. However, when challenged in vivo by infection with the intracellular pathogens Listeria monocytogenes or Mycobacterium tuberculosis, dbh-/- mice were more susceptible to infection, exhibited extreme thymic involution, and had impaired T cell function, including Th1 cytokine production. When immunized with trinitrophenyl-keyhole limpet hemocyanin, dbh-/- mice produced less Th1 cytokine-dependent-IgG2a antitrinitrophenyl antibody. These results indicate that physiological catecholamine production is not required for normal development of the immune system, but plays an important role in the modulation of T cell-mediated immunity to infection and immunization. (+info)
Genetic control of cytolytic T-lymphocyte responses. I. Ir gene control of the specificity of cytolytic T-lymphocyte responses to trinitrophenyl-modified syngeneic cells.
The ability of cytotoxic T lymphocytes (CTL) induced in vitro to trinitrophenyl (TNP)-modified syngeneic cells to cross-reactively lyse a TNP allogeneic spleen target varies among inbred mouse strains. The cross-reactive CTL phenotype was found to be histocompatibility 2 (H-2) linked and to be dominant in F1 hybrid mice. All strains investigated demonstrated cross-reactivity except for some strains bearing portions of the H-2k haplotype. The gene(s) controlling this response maps to the K and/or I-A region of the H-2 complex. We have termed the immune response (Ir) gene responsible for controlling the specificity of CTL induced to TNP-modified syngeneic cells Ir-X-TNP. (+info)