1
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Li SS, Ogbomo H, Mansour MK, Xiang RF, Szabo L, Munro F, Mukherjee P, Mariuzza RA, Amrein M, Vyas JM, Robbins SM, Mody CH. Identification of the fungal ligand triggering cytotoxic PRR-mediated NK cell killing of Cryptococcus and Candida. Nat Commun 2018; 9:751. [PMID: 29467448 PMCID: PMC5821813 DOI: 10.1038/s41467-018-03014-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 01/11/2018] [Indexed: 01/08/2023] Open
Abstract
Natural killer (NK) cells use the activating receptor NKp30 as a microbial pattern-recognition receptor to recognize, activate cytolytic pathways, and directly kill the fungi Cryptococcus neoformans and Candida albicans. However, the fungal pathogen-associated molecular pattern (PAMP) that triggers NKp30-mediated killing remains to be identified. Here we show that β-1,3-glucan, a component of the fungal cell wall, binds to NKp30. We further demonstrate that β-1,3-glucan stimulates granule convergence and polarization, as shown by live cell imaging. Through Src Family Kinase signaling, β-1,3-glucan increases expression and clustering of NKp30 at the microbial and NK cell synapse to induce perforin release for fungal cytotoxicity. Rather than blocking the interaction between fungi and NK cells, soluble β-1,3-glucan enhances fungal killing and restores defective cryptococcal killing by NK cells from HIV-positive individuals, implicating β-1,3-glucan to be both an activating ligand and a soluble PAMP that shapes NK cell host immunity. Natural killer (NK) cells has been show to mediate fungi killing via the activating receptor NKp30, but the fungal target for NKp30 is still unclear. Here the authors show, using atomic force microscopy and live cell imaging, that β-1,3-glucan is expressed by Cryptococcus neoformans and Candida albicans and responsible for NKp30-mediated NK killing.
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Affiliation(s)
- Shu Shun Li
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, T2N 4N1, Canada.,The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, T2N 4N1, Canada
| | - Henry Ogbomo
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, T2N 4N1, Canada.,The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, T2N 4N1, Canada
| | - Michael K Mansour
- Department of Medicine Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Richard F Xiang
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, T2N 4N1, Canada.,The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, T2N 4N1, Canada
| | - Lian Szabo
- Department of Medicine, University of Calgary, Calgary, T2N 4N1, Canada
| | - Fay Munro
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, T2N 4N1, Canada
| | - Priyanka Mukherjee
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, T2N 4N1, Canada
| | - Roy A Mariuzza
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Matthias Amrein
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, T2N 4N1, Canada
| | - Jatin M Vyas
- Department of Medicine Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Stephen M Robbins
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, T2N 4N1, Canada.,Southern Alberta Cancer Research Institute, University of Calgary, Calgary, T2N 4N1, Canada
| | - Christopher H Mody
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, T2N 4N1, Canada. .,The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, T2N 4N1, Canada. .,Department of Medicine, University of Calgary, Calgary, T2N 4N1, Canada.
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Abstract
Cryptococcus species are encapsulated fungi found in the environment that predominantly cause disease in immunocompromised hosts after inhalation into the lungs. Even with contemporary antifungal regimens, patients with cryptococcosis continue to have high morbidity and mortality rates. The development of more effective therapies may depend on our understanding of the cellular and molecular mechanisms by which the host promotes sterilizing immunity against the fungus. This review will highlight our current knowledge of how Cryptococcus, primarily the species C. neoformans, is sensed by the mammalian host and how subsequent signaling pathways direct the anti-cryptococcal response by effector cells of the innate immune system.
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Affiliation(s)
- Lena J Heung
- Infectious Diseases Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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3
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Requirement and redundancy of the Src family kinases Fyn and Lyn in perforin-dependent killing of Cryptococcus neoformans by NK cells. Infect Immun 2013; 81:3912-22. [PMID: 23918783 DOI: 10.1128/iai.00533-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Natural killer (NK) cells directly recognize and kill fungi, such as the pathogenic fungus Cryptococcus neoformans, via cytolytic mechanisms. However, the precise signaling pathways governing this NK cell microbicidal activity and the implications for fungal recognition are still unknown. Previously, it was reported that NK cell anticryptococcal activity is mediated through a conserved phosphatidylinositol 3-kinase-extracellular signal-regulated kinase 1/2 (PI3K-ERK1/2) pathway. Using YT (a human NK-like cell line) and primary human NK cells, we sought to identify the upstream, receptor-proximal signaling elements that led to fungal cytolysis. We demonstrate that Src family kinases were activated in response to C. neoformans. Furthermore, pharmacologic inhibition with an Src kinase inhibitor blocked C. neoformans-induced downstream activation of PI3K and ERK1/2 and abrogated cryptococcal killing. At the same time, the inhibitor disrupted the polarization of perforin-containing granules toward the NK cell-cryptococcal synapse but had no effect on conjugate formation between the organism and the NK cell. Finally, small interfering RNA (siRNA) double (but not single) knockdown of two Src family kinases, Fyn and Lyn, blocked cryptococcal killing. Together these data demonstrate a mechanism whereby the Src family kinases, Fyn and Lyn, redundantly mediate anticryptococcal activity through the activation of PI3K and ERK1/2, which in turn facilitates killing by inducing the polarization of perforin-containing granules to the NK cell-cryptococcal synapse.
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4
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Islam A, Li SS, Oykhman P, Timm-McCann M, Huston SM, Stack D, Xiang RF, Kelly MM, Mody CH. An acidic microenvironment increases NK cell killing of Cryptococcus neoformans and Cryptococcus gattii by enhancing perforin degranulation. PLoS Pathog 2013; 9:e1003439. [PMID: 23853583 PMCID: PMC3708852 DOI: 10.1371/journal.ppat.1003439] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 05/06/2013] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus gattii and Cryptococcus neoformans are encapsulated yeasts that can produce a solid tumor-like mass or cryptococcoma. Analogous to malignant tumors, the microenvironment deep within a cryptococcoma is acidic, which presents unique challenges to host defense. Analogous to malignant cells, NK cells kill Cryptococcus. Thus, as in tumor defense, NK cells must kill yeast cells across a gradient from physiologic pH to less than 6 in the center of the cryptococcoma. As acidic pH inhibits anti-tumor activities of NK cells, we sought to determine if there was a similar reduction in the anticryptococcal activity of NK cells. Surprisingly, we found that both primary human NK cells and the human NK cell line, YT, have preserved or even enhanced killing of Cryptococcus in acidic, compared to physiological, pH. Studies to explore the mechanism of enhanced killing revealed that acidic pH does not increase the effector to target ratio, binding of cytolytic cells to Cryptococcus, or the active perforin content in effector cells. By contrast, perforin degranulation was greater at acidic pH, and increased degranulation was preceded by enhanced ERK1/2 phosphorylation, which is essential for killing. Moreover, using a replication defective ras1 knockout strain of Cryptococcus increased degranulation occurred during more rapid replication of the organisms. Finally, NK cells were found intimately associated with C. gattii within the cryptococcoma of a fatal infection. These results suggest that NK cells have amplified signaling, degranulation, and greater killing at low pH and when the organisms are replicating quickly, which would help maintain microbicidal host defense despite an acidic microenvironment. Immune responses that protect from infection must occur in a variety of unique and potentially hostile environments. Within these environments, acidosis causes profound affects on protective responses. Low pH can occur in focal tumor-like infections, such as in a cryptococcoma produced by the fungal pathogen Cryptococcus. Similarly, low pH occurs in focal malignant tumors. It follows that Cryptococcus and malignant cells can both be killed by NK cells, which provide an important mechanism of host defense. Thus, we asked whether low pH, which impairs tumor killing, might also affect NK cell killing of Cryptococcus. Surprisingly, despite impaired tumor killing, NK cells possess enhanced killing of Cryptococcus at low pH. The mechanism involved a gain in intracellular signal transduction that led to enhanced perforin degranulation. This led us to examine NK cells in persistent cryptococcoma of a fatal brain infection and lung. We found that NK cells associate with Cryptococcus within the cryptococcoma, but perforin is reduced. These studies suggest NK cell cytotoxicity need not be impaired at low pH, and that enhanced signal transduction and degranulation at low pH might be used to enhance host defense.
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Affiliation(s)
- Anowara Islam
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Shu Shun Li
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Paul Oykhman
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Martina Timm-McCann
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Shaunna M. Huston
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Danuta Stack
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Richard F. Xiang
- Department of Medical Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Margaret M. Kelly
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christopher H. Mody
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
- Department of Internal Medicine, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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5
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Cryptococcus neoformans directly stimulates perforin production and rearms NK cells for enhanced anticryptococcal microbicidal activity. Infect Immun 2009; 77:2436-46. [PMID: 19307209 DOI: 10.1128/iai.01232-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
NK cells, in addition to possessing antitumor and antiviral activity, exhibit perforin-dependent microbicidal activity against the opportunistic pathogen Cryptococcus neoformans. However, the factors controlling this response, particularly whether the pathogen itself provides an activation or rearming signal, are largely unknown. The current studies were performed to determine whether exposure to this fungus alters subsequent NK cell anticryptococcal activity. NK cells lost perforin and mobilized lysosome-associated membrane protein 1 to the cell surface following incubation with the fungus, indicating that degranulation had occurred. Despite a reduced perforin content during killing, NK cells acquired an enhanced ability to kill C. neoformans, as demonstrated using auxotrophs that allowed independent assessment of the killing of two strains. De novo protein synthesis was required for optimal killing; however, there was no evidence that a soluble factor contributed to the enhanced anticryptococcal activity. Exposure of NK cells to C. neoformans caused the cells to rearm, as demonstrated by increased perforin mRNA levels and enhanced loss of perforin when transcription was blocked. Degranulation alone was insufficient to provide the activation signal as NK cells lost anticryptococcal activity following treatment with strontium chloride. However, NK cells regained the activity upon prolonged exposure to C. neoformans, which is consistent with activation by the microbe. The enhanced cytotoxicity did not extend to tumor killing since NK cells exposed to C. neoformans failed to kill NK-sensitive tumor targets (K562 cells). These studies demonstrate that there is contact-mediated microbe-specific rearming and activation of microbicidal activity that are necessary for optimal killing of C. neoformans.
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Jones GJ, Wiseman JCD, Marr KJ, Wei S, Djeu JY, Mody CH. In contrast to anti-tumor activity, YT cell and primary NK cell cytotoxicity for Cryptococcus neoformans bypasses LFA-1. Int Immunol 2009; 21:423-32. [PMID: 19261694 DOI: 10.1093/intimm/dxp010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
NK cell cytotoxicity requires two positive signals for killing of tumors. Activation receptors induce polarization of the microtubule organization center and degranulation, while leukocyte function-associated antigen (LFA)-1 is required for conjugate formation and actin polymerization and under some circumstances may be sufficient for NK cell cytotoxicity. Although the receptor for direct killing of fungi is not known, CD18, the beta2 chain of LFA-1, binds components of the capsule and cell wall of the opportunistic pathogen Cryptococcus neoformans, namely the polysaccharides glucoronoxylomannan and galactoxylomannan. Herein, we also demonstrate that LFA-1 was concentrated in regions of the NK cell surface interacting with C. neoformans. Consequently, there was compelling evidence to hypothesize that NK cells would also use LFA-1 to recognize and kill C. neoformans. Using a combination of NK cell lines that did or did not express LFA-1 or by using a CD18-specific functional blocking antibody, we confirm that NK cell anti-tumor activity is critically dependent upon the expression of LFA-1. Duplicating the events of tumor cytotoxicity, NK cells form conjugates with cryptococcal targets, rearrange the cell cytoskeleton to develop an NK immunologic synapse and release perforin-containing granules; however, each of these events occurred independently of LFA-1. Furthermore, NK cell-mediated killing of C. neoformans was detectable in both NK cells pre-treated with CD18-blocking antibodies and in NK cells lacking cell surface LFA-1 expression. These results demonstrate that in the absence of LFA-1 expression, NK cells are fully capable of recognizing a target (C. neoformans) and retain all of the events required for cytotoxicity.
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Affiliation(s)
- Gareth J Jones
- Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
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7
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Ma LL, Wang CLC, Neely GG, Epelman S, Krensky AM, Mody CH. NK Cells Use Perforin Rather than Granulysin for Anticryptococcal Activity. THE JOURNAL OF IMMUNOLOGY 2004; 173:3357-65. [PMID: 15322199 DOI: 10.4049/jimmunol.173.5.3357] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cytotoxic lymphocytes have the capacity to kill microbes directly; however, the mechanisms involved are poorly understood. Using Cryptococcus neoformans, which causes a potentially fatal fungal infection in HIV-infected patients, our previous studies showed that granulysin is necessary, while perforin is dispensable, for CD8 T lymphocyte fungal killing. By contrast, the mechanisms by which NK cells exert their antimicrobial activity are not clear, and in particular, the contribution of granulysin and perforin to NK-mediated antifungal activity is unknown. Primary human NK cells and a human NK cell line YT were found to constitutively express granulysin and perforin, and possessed anticryptococcal activity, in contrast to CD8 T lymphocytes, which required stimulation. When granulysin protein and mRNA were blocked by granulysin small interfering RNA, the NK cell-mediated antifungal effect was not affected in contrast to the abrogated activity observed in CD8 T lymphocytes. However, when perforin was inhibited by concanamycin A, and silenced using hairpin small interfering RNA, the anticryptococcal activities of NK cells were abrogated. Furthermore, when granulysin and perforin were both inhibited, the anticryptococcal activities of the NK cells were not reduced further than by silencing perforin alone. These results indicate that the antifungal activity is constitutively expressed in NK cells in contrast to CD8 T lymphocytes, in which it requires prior activation, and perforin, but not granulysin, plays the dominant role in NK cell anticryptococcal activity, in contrast to CD8 T lymphocytes, in which granulysin, but not perforin, plays the dominant role in anticryptococcal activity.
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Affiliation(s)
- Ling Ling Ma
- Department of Medical Sciences, University of Calgary, Alberta, Canada
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8
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Kawakami K, Koguchi Y, Qureshi MH, Yara S, Kinjo Y, Uezu K, Saito A. NK cells eliminate Cryptococcus neoformans by potentiating the fungicidal activity of macrophages rather than by directly killing them upon stimulation with IL-12 and IL-18. Microbiol Immunol 2001; 44:1043-50. [PMID: 11220678 DOI: 10.1111/j.1348-0421.2000.tb02601.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the present study, we examined whether natural killer (NK) cells have direct fungicidal activity against Cryptococcus neoformans. Splenic NK cells were obtained from SCID mice and stimulated with a combination of interleukin (IL)-12 and IL-18 in flat culture plates or round tubes. They were then or at the same time cultured with the yeast cells and the number of viable yeast cells was examined. We could not detect direct fungicidal activity by NK cells under any culture condition, although they produced a large amount of IFN-gamma and exerted marked cytotoxic activity against YAC-1 cells. On the other hand, NK cells significantly potentiated the nitric oxide-mediated cryptococcocidal activity of thioglycolate-elicited peritoneal macrophages obtained from SCID mice upon stimulation with IL-12 and IL-18. The culture supernatants of NK cells stimulated with IL-12 and IL-18 provided similar results when used in place of NK cells. The induction of macrophage anticryptococcal activity by NK cells and NK cell culture supernatants were both mediated by IFN-gamma because the specific mAb almost completely abrogated such effect. Considered collectively, our results suggested that NK cells may play a regulatory role in potentiating macrophage-mediated fungicidal mechanisms in host resistance to infection with C. neoformans rather than exerting a direct killing activity against the fungal pathogen.
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Affiliation(s)
- K Kawakami
- The First Department of Internal Medicine, Faculty of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan.
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Ogata K, An E, Shioi Y, Nakamura K, Luo S, Yokose N, Minami S, Dan K. Association between natural killer cell activity and infection in immunologically normal elderly people. Clin Exp Immunol 2001; 124:392-7. [PMID: 11472399 PMCID: PMC1906081 DOI: 10.1046/j.1365-2249.2001.01571.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Congenital patients who lack natural killer (NK) cell activity experience repeated polymicrobial infections. NK cell activity varies significantly among normal people, but it is unknown whether this variation influences their ability to fight infections. This study examined this concern. NK cell activity and other variables, i.e. age, sex, performance status (PS), serum albumin value, lymphocyte and neutrophil counts, various lymphocyte subsets, etc. were determined for 108 immunologically normal elderly subjects who were in nursing homes due to an impaired PS. We analysed for correlations between these variables and the follow-up results of the subjects. Forty-eight subjects developed infection(s) during the first year of follow-up. A low NK cell activity was associated with the development of infection (P = 0.0105, multivariate logistic regression analysis). The relative risk for the development of infection increased in accordance with the decrease in the NK cell activity. Eleven subjects died of infection during the study period. A low NK cell activity was associated with short survival due to infection (P = 0.0056, multivariate Cox's proportional-hazards regression analysis). Our data indicate that low NK cell activity is associated with development of infections and death due to infection in immunologically normal elderly subjects with an impaired PS.
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Affiliation(s)
- K Ogata
- Division of Haematology, Third Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
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Murphy JW, Zhou A, Wong SC. Direct interactions of human natural killer cells with Cryptococcus neoformans inhibit granulocyte-macrophage colony-stimulating factor and tumor necrosis factor alpha production. Infect Immun 1997; 65:4564-71. [PMID: 9353034 PMCID: PMC175655 DOI: 10.1128/iai.65.11.4564-4571.1997] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human natural killer (NK) cells and T lymphocytes can bind to and inhibit the growth of the yeast-like organism Cryptococcus neoformans. Binding of target cells to NK or T cells also has the potential to modulate cytokine production by the effector cells. In this study, we assessed the ability of C. neoformans to modulate NK cell production, or in some cases T-cell production, of granulocyte-macrophage colony-stimulating factor (GM-CSF) or tumor necrosis factor alpha (TNF-alpha). We found that freshly isolated human NK cells from most individuals make GM-CSF and TNF-alpha constitutively when cultured in vitro. The addition of C. neoformans to T-cell fractions which do not make GM-CSF constitutively did not affect GM-CSF production, but the addition of C. neoformans to NK cell fractions significantly reduced the amounts of GM-CSF produced in most NK cell samples. The reduction in the amount of GM-CSF in C. neoformans-NK cell cocultures could not be attributed to loss of lymphocyte viability or to C. neoformans adsorbing or degrading the cytokine and was dependent on direct contact between the NK cells and cryptococcal cells. GM-CSF was not the only cytokine to be down-regulated. TNF-alpha production was also diminished when NK cells were incubated with C. neoformans. The regulation of both cytokines was at the transcriptional level because GM-CSF and TNF-alpha mRNA levels were lower in NK cell samples incubated with C. neoformans than in NK cell samples incubated without C. neoformans. Diminished production of constitutively produced cytokines resulting from the interaction of NK cells with cryptococcal cells has the potential to affect phagocytic cells in the immediate regional environment and to damp the immune response.
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
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11
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Ogata K, Yokose N, Tamura H, An E, Nakamura K, Dan K, Nomura T. Natural killer cells in the late decades of human life. CLINICAL IMMUNOLOGY AND IMMUNOPATHOLOGY 1997; 84:269-75. [PMID: 9281385 DOI: 10.1006/clin.1997.4401] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We examined the lymphocyte subsets and indices of natural killer (NK) cell activity (lytic unit (LU), index of absolute NK cell activity in vivo (ALU), and NK cell activity on a per-cell basis (PCNK)) in 82 people (age, 30-99 years) who were immunologically normal. Although the number of NK cells was maintained throughout the examined age range, the ALU and PCNK values correlated negatively with age. We then examined whether any of the various immunologic parameters, including the function and cell counts of NK cells, T cells, and neutrophils, related to past infectious episodes and death in the follow-up period in 44 elderly subjects (age, 63-98 years). Only low ALU and PCNK values correlated with a past history of severe infection, while low LU, ALU, and PCNK values were the only parameters which correlated with death due to infection during the follow-up period. We propose that human NK cells do not escape the aging process and that a low NK cell function relates to the development of severe infections, which may be fatal, in elderly subjects.
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Affiliation(s)
- K Ogata
- Third Department of Internal Medicine, Nippon Medical School, Sendagi 1-1-5, Tokyo, Bunkyo-ku, 113, Japan
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12
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Mathews HL, Lorens SA, Clancy J. Effect of d-fenfluramine on the local immune response to the opportunistic microbial pathogen Candida albicans. Behav Brain Res 1995; 73:369-74. [PMID: 8788534 DOI: 10.1016/0166-4328(96)00117-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In this study the effects of systemic administration of d-fenfluramine on the local lymphocyte response to Candida albicans was evaluated. Experimental animals were challenged intradermally with Candida albicans and then administered d-fenfluramine (d-FEN 1 mg/kg per day, i.p.) or a balanced salts solution. At successive time intervals, lymphocytes were derived from the draining lymph nodes and from the dermal sites of active microbial challenge. A CD8+ lymphocytosis was observed in all animals challenged with Candida albicans. The CD8+ lymphocytosis was augmented in animals that received d-FEN. Phenotypically, lymph nodes from d-FEN treated animals showed a marked increase in CD3+ and CD8+ lymphocytes, a modest increase in the numbers of NK1.1+ cells and a decrease in Ig+ lymphocytes. Functionally, lymphocytes from the site of active microbial challenge were capable of direct growth inhibition of Candida albicans. The anti-fungal activity was augmented in the animals that received d-FEN. These results suggest that d-FEN augments the local T lymphocyte response to an important microbial pathogen by increasing the number of T lymphocytes draining the site of microbial infection and by increasing the biological activity of the lymphocytes at the site of the infection.
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Affiliation(s)
- H L Mathews
- Department of Microbiology and Immunology, Loyola University of Chicago, Maywood, IL 60153, USA
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13
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Abstract
T cells are generally thought to contribute to antimicrobial activity either by releasing lymphokines, which recruit and activate other cell types, or by major histocompatibility complex (MHC)-restricted lysis of infected host cells. Recently, it has become apparent that T cells can also mediate antimicrobial activity by direct interaction with microbial targets. Such interactions, which can be either antigen specific or nonspecific, occur in the apparent absence of MHC restriction and do not require the presence of other host cells. Microbial targets recognized by T cells include fungi, parasites and bacteria. Here, Stuart Levitz, Herbert Mathews and Juneann Murphy discuss the direct antimicrobial activity of T cells and speculate on its in vivo relevance.
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Affiliation(s)
- S M Levitz
- Evans Memorial Dept of Clinical Research, Boston University Medical Center Hospital, MA 02118, USA
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14
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Muth SM, Murphy JW. Direct anticryptococcal activity of lymphocytes from Cryptococcus neoformans-immunized mice. Infect Immun 1995; 63:1637-44. [PMID: 7729867 PMCID: PMC173203 DOI: 10.1128/iai.63.5.1637-1644.1995] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Assessment of the direct anticryptococcal activity of murine lymphocytes from both Cryptococcus neoformans-immunized and control mice was the focus of this investigation. We demonstrate that at a 2:1 effector cell-to-cryptococcal target cell ratio, effector cell populations comprised of alpha beta T-cell receptor-positive T lymphocytes (98 to 99% CD3+) from C. neoformans-immunized mice inhibited the growth of cryptococcal cells better than similar populations of lymphocytes from nonimmunized control mice. Almost immediately after mixing of cryptococci with the effector cells, C. neoformans-lymphocyte conjugates were observed. The percentage of conjugates increased over the first 30 min of incubation and then remained constant over the next 1.5 h. T-lymphocyte-enriched populations from C. neoformans-immunized mice formed significantly greater percentages of conjugates with cryptococci than control T lymphocytes at each time period that assessment was made. For growth inhibition to occur, direct contact between the effector and target cells was necessary, as evidenced by abrogation of cryptococcal growth inhibition when lymphocyte and cryptococcal cell populations were separated by a porous membrane during the growth inhibition assay. Vital staining of cryptococci after incubation with the T-cell-enriched populations showed that the T lymphocytes killed the cryptococcal cells.
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Affiliation(s)
- S M Muth
- Department of Microbiology and Immunology, University of Oklahoma Health Science Center, Oklahoma City 73190, USA
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15
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Arancia G, Molinari A, Crateri P, Stringaro A, Ramoni C, Dupuis ML, Gomez MJ, Torosantucci A, Cassone A. Noninhibitory binding of human interleukin-2-activated natural killer cells to the germ tube forms of Candida albicans. Infect Immun 1995; 63:280-8. [PMID: 7806367 PMCID: PMC172989 DOI: 10.1128/iai.63.1.280-288.1995] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
During incubation in vitro with yeast or germ tube forms of Candida albicans, only 2 to 6% of freshly isolated human natural killer (NK) cells (> 85% CD16+, CD56+, CD3-; < 15% CD3+; cytolytic for the NK-susceptible target K562 but not for the NK-resistant target DAUDI), were seen to interact with the fungal cells. As seen under the electron microscope, the contact area had a limited extent and was narrow, and neither the surface nor the intracytoplasmic organization of the NK cell was altered. In contrast, more than 30% of interleukin-2-activated NK (LAK) cells (> 96% CD16+, CD56+, CD3-; 1.5% CD3+; cytolytic for both K562 and DAUDI targets) interacted closely with the fungus. This interaction was particularly extensive with the surface of the fungal germ tube that was intimately enveloped by villous protrusions from the lymphocyte surface. The fungus-interacting LAK cell also showed a remarkable redistribution of surface microvilli and polarization of cytoplasmic organelles, such as the Golgi apparatus, centrioles, and granules, toward the area of fungal contact. Together with the elevated cytolytic potential against the K562 and DAUDI targets, all the morphological data suggested the presence of a potentially active lytic machinery in the fungus-interacting LAK cell. Nonetheless, two independent assays for anticandidal activity did not show consistent killing or fungal growth inhibition by either fresh NK or LAK cells. While offering direct evidence of the strong interaction between human LAK cells and the germ tubes, precursors of tissue-invasive hyphal forms of C. albicans, our observations also suggest that this interaction may not be sufficient to kill the fungus or arrest its growth.
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Affiliation(s)
- G Arancia
- Department of Ultrastructures, Istituto Superiore di Sanità, Rome, Italy
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16
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Clemons KV, Brummer E, Stevens DA. Cytokine treatment of central nervous system infection: efficacy of interleukin-12 alone and synergy with conventional antifungal therapy in experimental cryptococcosis. Antimicrob Agents Chemother 1994; 38:460-4. [PMID: 7911289 PMCID: PMC284480 DOI: 10.1128/aac.38.3.460] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Cell-mediated immune responses appear to be critical in the outcome of cryptococcosis. Interleukin-12 (IL-12) was studied for its potential use as a therapeutic agent because of its stimulation of natural killer cells and gamma interferon production by stimulated T cells and natural killer cells. Gamma interferon-activated macrophages are important in host resistance against cryptococcosis. In two separate studies, male BALB/c mice were infected intravenously with Cryptococcus neoformans. In the first study, mice received either no treatment, 5.0 mg of fluconazole alone per kg of body weight per day (by gavage twice daily), or IL-12 subcutaneously at 0.01, 0.1, or 1.0 microgram/day once daily (low-dose study) alone or in combination with 5.0 mg of fluconazole per kg/day. In a second study (high dose), the dosages of IL-12 used were 1.0, 2.5, or 5.0 micrograms/day. Therapy was given for 10 consecutive days, and the number of CFU of C. neoformans remaining in various organs was quantitated 1 or 2 days after administration of the last dose. In the low-dose study, IL-12 at 0.1 or 1.0 microgram reduced the level of brain infection by approximately 10-fold (P < 0.05) and IL-12 at 1.0 or 0.1 microgram/day enhanced the efficacy of fluconazole. In liver, both the efficacy of IL-12 alone (0.01 or 0.1 microgram; P < 0.05) and enhancement of the efficacy of fluconazole (P < 0.05) were seen. No efficacy of IL-12 was seen in spleens or lungs, although spleen weights increased fourfold in mice given 1.0 microgram of IL-12 per day. In the high-dose study, all IL-12 doses alone again reduced the levels of brain infection (5- to 8-fold; P < 0.05) when the two were given in combination. No overt toxicities were observed at any dose, and overall, 1.0 microgram of IL-12 per day was found to be the optimal dosage for reducing infection in the brain. To our knowledge, this is the first demonstration of the efficacy of cytokine therapy in systemic and particularly brain infections with C. neoformans. The stimulation of cell-mediated immunity represents a new approach to therapy and can enhance suboptimal antimicrobial chemotherapy. IL-12 should be considered for further study and for clinical trials. These studies suggest that other opportunistic central nervous system pathogens should also be investigated.
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Affiliation(s)
- K V Clemons
- Department of Medicine, Santa Clara Valley Medical Center, San Jose, CA 95128-2699
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17
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Murphy JW, Hidore MR, Wong SC. Direct interactions of human lymphocytes with the yeast-like organism, Cryptococcus neoformans. J Clin Invest 1993; 91:1553-66. [PMID: 8473499 PMCID: PMC288131 DOI: 10.1172/jci116361] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Lymphocytes, especially CD4+ T cells, are essential for clearance of the yeast-like organism Cryptococcus neoformans from the infected host. The mechanism(s) by which the lymphocytes facilitate elimination of cryptococci has not been elucidated. It is generally thought, however, that lymphocytes reactive with C. neoformans indirectly function by production of lymphokines to enhance clearance of the organism by natural effector cells such as macrophages. In the present study, we assessed the ability of freshly isolated human lymphocytes to interact directly with C. neoformans and to limit the growth of the organism in vitro. We found that large granular lymphocytes (LGL) as well as T cells bound to cryptococcal cells when the lymphocytes were mixed with the cryptococcal cells at a 2:1 ratio. The physical binding interactions of the two lymphocyte populations were different. LGL attached to the cryptococcal cells by many microvilli; T lymphocytes associated with the yeast through broad areas of membrane attached to the cryptococcal cell surface. The two types of lymphocyte interactions did not result in phagocytosis but resulted in direct inhibition of cryptococcal growth, making these lymphocyte interactions with cryptococci distinctly different from interactions of monocytes with cryptococci. With the human natural killer (NK) cell line, NK 3.3, we confirmed that NK cells that were present in the LGL population were capable of limiting the growth of C. neoformans. Through immunoelectron microscopy, human CD3+ lymphocytes were seen attached to cryptococcal cells and by mass cytolysis, human CD3+ lymphocytes were shown to be responsible for inhibition of C. neoformans growth. The direct inhibitory interactions of NK cells and T lymphocytes with cryptococcal cells may be important means of host defense against this ubiquitous organism that frequently causes life-threatening disease in AIDS patients.
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190
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18
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Murphy JW. Natural killer cells and Cryptococcus neoformans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1993; 335:269-75. [PMID: 8237604 DOI: 10.1007/978-1-4615-2980-4_37] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- J W Murphy
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, Oklahoma City
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19
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20
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Sato MN, Yamashiro-Kanashiro EH, Tanji MM, Kaneno R, Higuchi ML, Duarte AJ. CD8+ cells and natural cytotoxic activity among spleen, blood, and heart lymphocytes during the acute phase of Trypanosoma cruzi infection in rats. Infect Immun 1992; 60:1024-30. [PMID: 1541517 PMCID: PMC257589 DOI: 10.1128/iai.60.3.1024-1030.1992] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The infection developed by Wistar Furth rats inoculated with the Y strain of Trypanosoma cruzi was the experimental model used in our study. The results showed that this infection altered considerably the CD4/CD8 lymphocyte subset ratio and the natural cytotoxic activity of mononuclear cells in the spleen, blood, and myocardial tissue. Concomitantly, an expansion of the number of cells expressing major histocompatibility complex (MHC) class II antigens was observed, as well as spontaneous development of high levels of blast cells, mainly in the spleen. The inflammatory infiltration of the myocardium, made up essentially of CD8+ cells (cytotoxic/suppressor T cells, natural killer cells), was initially found at 9 days postinfection, spread continuously, and was observed until the death of the animals at about 18 days postinfection. T. cruzi infection also enhanced the natural killer activity of mononuclear cells in the blood, spleen, and myocardium. Sorting these cells by affinity columns showed that the natural killer function was performed exclusively by the CD8+ population, which did not express MHC class II antigens. It was shown that the polyclonal T-lymphocyte activation induced by T. cruzi infection results in a wide distribution of CD8+ cells with enhanced natural cytotoxic activity in the spleen, blood, and cardiac tissue.
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Affiliation(s)
- M N Sato
- Departamento de Clínica Médica, Faculdade de Medicina, Universidade de São Paulo, Brazil
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21
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Blasi E, Mazzolla R, Barluzzi R, Bistoni F. Microglial cell-mediated anti-Candida activity: temperature, ions, protein kinase C as crucial elements. J Neuroimmunol 1991; 34:53-60. [PMID: 1894734 DOI: 10.1016/0165-5728(91)90098-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
An in vitro established microglial cell line, BV-2, constitutively exhibits high levels of anti-Candida activity. To elucidate the cascade of events leading to the accomplishment of such activity, we studied its dependence on temperature and ion availability. The role of protein kinases has also been studied by the specific inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H7) and N-(2-guanidinoethyl)-5-isoquinoline sulfonamide hydrochloride (HA 1004). We found that (a) the BV-2 cell/Candida conjugate formation is a discrete step, temperature-, ion- and protein kinase-independent; (b) the phagocytic event, which is protein kinase-independent, is significantly impaired by temperature decrease and ion deprivation; (c) the fulfillment of anti-Candida effects is strictly dependent upon temperature, ion availability and functional protein kinase. Functional protein kinase C, but not other kinases, is required for the accomplishment of anti-Candida activity, which, in fact, is selectively abrogated by H7 but not HA. Furthermore, protein kinase C activators, such as 12-O-tetradecanoylphorbol 13-acetate (TPA) or 1-oleoyl-2-acetyl glycerol (OAG), consistently potentiate BV-2 cell-mediated anti-Candida activity, the phenomena being dose-dependent. These results indicate that the multistep events leading a microglial cell to express anti-Candida activity can be dissected and differentiated for biochemical and biological demands, the latest along the cascade being the most demanding steps.
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Affiliation(s)
- E Blasi
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy
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22
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Harshan KV, Gangadharam PR. In vivo depletion of natural killer cell activity leads to enhanced multiplication of Mycobacterium avium complex in mice. Infect Immun 1991; 59:2818-21. [PMID: 1855997 PMCID: PMC258091 DOI: 10.1128/iai.59.8.2818-2821.1991] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Earlier investigations have shown that murine natural killer (NK) cells inhibit the growth of fungal and bacterial pathogens in vivo and in vitro. In order to define the role of NK cells in Mycobacterium avium complex infection, in vivo depletion of NK cells by using anti-NK1.1 monoclonal antibody and conventional anti-asialo-GM1 antibody has been attempted. Repeated injection of 200 micrograms of anti-NK1.1 or 50 micrograms of anti-asialo-GM1 antibody effectively depleted NK activity in the spleens of C57BL/6 mice. The growth kinetics of M. avium complex over a period of 4 weeks showed that the colony counts in the spleens of the antibody-treated group were significantly (P less than 0.01) higher than those of the control group and compared well with those of the genetically NK cell-deficient C57BL/6 bg/bg mutant. The alternate strategy of in vivo stimulation of NK activity by poly(I:C) administration did not show a similar reduction in CFU in the spleen compared with the untreated control. The in vivo antibody depletion of NK activity provides direct evidence on the role of NK cells in the control of intracellular mycobacterial pathogens such as M. avium complex.
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Affiliation(s)
- K V Harshan
- Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206
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23
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Hidore MR, Nabavi N, Sonleitner F, Murphy JW. Murine natural killer cells are fungicidal to Cryptococcus neoformans. Infect Immun 1991; 59:1747-54. [PMID: 1708359 PMCID: PMC257911 DOI: 10.1128/iai.59.5.1747-1754.1991] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Murine natural killer (NK) cells have been shown to bind to and inhibit the growth of Cryptococcus neoformans in vitro and to contribute to clearance of the organism in vivo. However, it is unclear whether NK cells actually kill cryptococci or simply inhibit proliferation of the fungal target. Therefore, the studies presented here were designed to determine whether NK cells are fungicidal to C. neoformans targets. C. neoformans viability was determined on the basis of the metabolic function of two different enzyme systems, as measured by the two vital stains MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and fluorescein diacetate. Cryptococcal viability, as determined by vital stains, was compared with cryptococcal proliferation, as measured by microcolony formation in agarose at the individual cell level and by CFU counts or extinction dilution analysis in the total cell suspension. Initial comparisons of the vital stains and proliferation assays indicated that these methods effectively distinguished between live and heat-killed cryptococci at the individual cell level and in the total cell suspensions. After cryptococci were incubated with murine NK cells for 18 h, vital stains demonstrated that at the single conjugate level and in the total cell suspension, NK cells kill bound C. neoformans target cells. In addition, the numbers of dead cryptococci in the NK cell-C. neoformans suspensions as determined by the vital stains were comparable to the numbers of cryptococci that were unable to proliferate. Kinetics of NK cell-mediated C. neoformans binding and killing at the single conjugate level and in the total cell suspension were assessed by MTT staining at 2-h intervals after mixing effector and target cells, and the data support the concept that NK cell-C. neoformans binding precedes cryptococcal death. Furthermore, unbound, dead fungal cells were observed in the NK cell-C. neoformans suspensions after 18 h, suggesting that NK cell-C. neoformans interactions may involve both effector cell recycling and killing of unbound cryptococci by soluble cytotoxic factors. In conclusion, the results of these studies firmly establish that NK cells kill C. neoformans.
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Affiliation(s)
- M R Hidore
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190
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24
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Hidore MR, Mislan TW, Murphy JW. Responses of murine natural killer cells to binding of the fungal target Cryptococcus neoformans. Infect Immun 1991; 59:1489-99. [PMID: 2004827 PMCID: PMC257867 DOI: 10.1128/iai.59.4.1489-1499.1991] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Natural killer (NK) cells bind to and inhibit the growth of the fungal target Cryptococcus neoformans. Since C. neoformans is structurally and chemically distinct from the standard tumor cell target used in the model of NK cell-mediated cytotoxicity, this study was designed to investigate the NK cell response after binding to cryptococci. Transmission electron micrographs and three-dimensional reconstructions of NK cell-cryptococci conjugates demonstrated focusing of the NK cell centrioles and Golgi apparatus toward the cryptococcal attachment site. NK cell cytoskeletal changes after cryptococcal binding were confirmed by immunofluorescence studies in which NK cells were allowed to bind to cryptococci in Mg2(+)-containing, Ca2(+)-free medium. One hour after the addition of Ca2+ to the preformed conjugates, the bound NK cells demonstrated a significant increase in the percentage of microtubule organizing centers focused toward the cryptococcal binding site. Colchicine, a drug that inhibits microtubule assembly, did not affect NK cell-cryptococci binding but abrogated NK cell-mediated cryptococcal growth inhibition, indicating that microtubule assembly, an important prerequisite for the secretory process, is not required for NK cell-cryptococci binding but is essential for inhibition of cryptococcal growth. In addition, the Ca2+ channel-blocking reagents, lidocaine and verapamil, did not affect NK cell-cryptococci binding but blocked the NK cell-mediated anticryptococcal activity, suggesting that a Ca2+ flux is essential for inhibition of cryptococcal growth. Considered together, these data indicate that NK cells respond to binding of a target cell that has a capsule and cell wall, in addition to a cell membrane, in a manner similar to that seen following binding to target cells that are surrounded by only a cell membrane; however, the response of the NK cells to the binding of C. neoformans is slower and possibly less efficient than the response after tumor cell binding.
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Affiliation(s)
- M R Hidore
- University of Oklahoma Health Sciences Center, Oklahoma City 73190
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25
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Murphy JW, Hidore MR, Nabavi N. Binding interactions of murine natural killer cells with the fungal target Cryptococcus neoformans. Infect Immun 1991; 59:1476-88. [PMID: 2004826 PMCID: PMC257866 DOI: 10.1128/iai.59.4.1476-1488.1991] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Murine natural killer (NK) cells have been shown to inhibit the growth of the yeastlike organism Cryptococcus neoformans both in vivo and in vitro. An essential first step in NK cell-mediated damage of cryptococcal cells is the binding of the NK cell to the cryptococcal cell. The studies presented here focused on the binding event. Electron photomicrographs and three-dimensional reconstructions of NK cell-C. neoformans conjugates show that NK cells bind to cryptococci through many microvilli. This is in contrast to the broad membrane-membrane interactions which form the binding site of NK cell-YAC-1 tumor cell conjugates. NK cell binding to cryptococci is much slower than NK cell binding to YAC-1 targets. Maximal conjugate formation with cryptococcal targets is reached after 2 h, whereas maximal conjugate formation with YAC-1 targets is obtained after 20 min. Once maximum NK cell-C, neoformans conjugate formation is obtained, another 4 h is required before damage to the cryptococcal cells can be detected with the CFU assay. These data indicate that the binding and action of NK cells on C. neoformans cells requires considerably more time than is necessary for similar events to occur in the NK cell-tumor cell model. NK cell membrane integrity is necessary for NK cells to bind to tumor targets, since some disruption of membrane integrity with 0.1 M dimethyl sulfoxide reduces conjugate formation and tumor cell lysis. In contrast, 0.1 M dimethyl sulfoxide did not diminish NK cell binding to cryptococcal targets; however, it significantly reduced cryptococcal growth inhibition. Although we have observed several differences in NK cell binding to the cryptococcal target compared with NK cell binding to tumor cell targets, there are some similarities in binding interactions of NK cells with the two different targets. Disulfide bonding appears to play a role in the binding of NK cells to both targets, since 5 mM 2-mercaptoethanol, a reagent that reduces disulfide bonds, prevented NK cells from binding to the tumor targets as well as the cryptococcal targets. Actin filaments, components of the cytoskeletal network, must be intact for NK cells to bind to YAC-1 cells or cryptococci. Taken together, our data confirm that binding of NK cells to the cryptococcal target is prerequisite to the stages that result in damage to the cryptococcal cell and that there are similarities and differences in NK cell-binding interactions with structurally different target cells.
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190
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26
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Salkowski CA, Balish E. A monoclonal antibody to gamma interferon blocks augmentation of natural killer cell activity induced during systemic cryptococcosis. Infect Immun 1991; 59:486-93. [PMID: 1898905 PMCID: PMC257776 DOI: 10.1128/iai.59.2.486-493.1991] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
These studies demonstrate that the cytotoxic activity of splenic natural killer (NK) cells is augmented in both nu/nu and nu/+ mice during systemic cryptococcosis. Both the kinetics and the regulation of NK cell activity differed in Cryptococcus neoformans-infected nu/nu and nu/+ mice. Greater augmentation was observed following challenge with 10(5) cells than with smaller inocula, and augmented NK cell activity was not always associated with enhanced control of systemic cryptococcosis. Infection with a nonencapsulated strain of C. neoformans induced an early but transient increase in splenic NK cell activity in nu/nu and nu/+ mice. Injection of capsular polysaccharide induced a transient augmentation of splenic NK cell activity in nu/+ mice but caused a persistent increase in splenic NK cell activity in nu/nu mice. In vivo treatment with monoclonal antibody to gamma interferon abrogated the augmentation of splenic NK cell activity induced during cryptococcal infections in both nu/nu and nu/+ mice and enhanced the susceptibility of nu/+ mice to C. neoformans to a greater extent than it did that of nu/nu mice. These results suggest that gamma interferon is an important mediator of resistance to C. neoformans.
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Affiliation(s)
- C A Salkowski
- Department of Surgery, University of Wisconsin Medical School, Madison 53706
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Peraçoli MT, Soares AM, Mendes RP, Marques SA, Pereira PC, Rezkallah-Iwasso MT. Studies of natural killer cells in patients with paracoccidioidomycosis. JOURNAL OF MEDICAL AND VETERINARY MYCOLOGY : BI-MONTHLY PUBLICATION OF THE INTERNATIONAL SOCIETY FOR HUMAN AND ANIMAL MYCOLOGY 1991; 29:373-80. [PMID: 1815029 DOI: 10.1080/02681219180000601] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The number and activity of natural killer (NK) cells were studied in 34 untreated patients with paracoccidioidomycosis, 20 with the chronic form of the disease and 14 with the acute form. NK cells were detected with monoclonal antibody Leu-11c and the cytotoxic activity was measured using a single cell assay against K562 target cells. Both groups of patients had an increased number of circulating NK cells, their cytotoxic activity being significantly lower than in the healthy controls. These findings may be of importance in the immunological disturbances associated with paracoccidioidomycosis since NK cells exert important immune effector functions and may play a role in resistance against Paracoccidiodes brasiliensis.
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Affiliation(s)
- M T Peraçoli
- Department of Microbiology and Immunology, São Paulo State University, UNESP, Brazil
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28
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Affiliation(s)
- J W Murphy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City
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