scholarly journals Simultaneous Measurement of Antigen-Stimulated Interleukin-1β and Gamma Interferon Production Enhances Test Sensitivity for the Detection of Mycobacterium bovis Infection in Cattle

2010 ◽  
Vol 17 (12) ◽  
pp. 1946-1951 ◽  
Author(s):  
Gareth J. Jones ◽  
Chris Pirson ◽  
R. Glyn Hewinson ◽  
H. Martin Vordermeier
Keyword(s):  
Mycobacterium Bovis ◽  
Gamma Interferon ◽  
Interleukin 1Β ◽  
Induced Responses ◽  
Readout System ◽  
Necrosis Factor Alpha ◽  
Test Sensitivity ◽  
Inflammatory Protein ◽  
Tnf Α ◽  
Ifn Γ

ABSTRACT In order to identify cytokines that may be useful as candidates for inclusion in diagnostic tests for Mycobacterium bovis infection in cattle, we compared the levels of gamma interferon (IFN-γ), interleukin 1β (IL-1β), IL-4, IL-10, IL-12, macrophage inflammatory protein 1β (MIP-1β), and tumor necrosis factor alpha (TNF-α) in whole-blood cultures from tuberculosis (TB) reactor animals or TB-free controls following stimulation with M. bovis-specific antigens (purified protein derivative from M. bovis [PPD-B] or ESAT-6/CFP-10). In addition to IFN-γ responses, the production of IL-1β and TNF-α was also statistically significantly elevated in TB reactor cattle over that in uninfected controls following stimulation with PPD-B or ESAT-6/CFP-10 peptides. Thus, we evaluated whether the use of these two additional readouts could disclose further animals not detected by measuring IFN-γ alone. To this end, receiver operating characteristic (ROC) analyses were performed to define diagnostic cutoffs for positivity for TNF-α and IL-1β. These results revealed that for ESAT-6/CFP-10-induced responses, the use of all three readouts (IFN-γ, TNF-α, and IL-1β) in parallel increased the sensitivity of detection of M. bovis-infected animals by 11% but also resulted in a specificity decrease of 14%. However, applying only IFN-γ and IL-1β in parallel resulted in a 5% increase in sensitivity without the corresponding loss of specificity. The results for PPD-B-induced responses were similar, although the loss of specificity was more pronounced, even when only IFN-γ and IL-1β were used as readout systems. In conclusion, we have demonstrated that the use of an additional readout system, such as IL-1β, can potentially complement IFN-γ by increasing overall test sensitivity for the detection of M. bovis infection in cattle.

scholarly journals Gamma Interferon and Lipopolysaccharide Interact at the Level of Transcription To Induce Tumor Necrosis Factor Alpha Expression

2001 ◽  
Vol 69 (5) ◽  
pp. 2847-2852 ◽  
Author(s):  
Julia Y. Lee ◽  
Kathleen E. Sullivan
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Gamma Interferon ◽  
Necrosis Factor Alpha ◽  
Rnase Protection ◽  
Tnf Α ◽  
Factor Alpha ◽  
Ifn Γ ◽  
Necrosis Factor

ABSTRACT Lipopolysaccharide (LPS) is a very potent inducer of tumor necrosis factor alpha (TNF-α) expression from monocytes and macrophages. Another inflammatory cytokine, gamma interferon (IFN-γ), can potentiate the effects of LPS, but the mechanism is not thoroughly understood. Previous reports emphasized the ability of IFN-γ to upregulate CD14 expression (the receptor for LPS), and nearly all studies have utilized sequential stimulation with IFN-γ followed by LPS to exploit this phenomenon. This study demonstrates that IFN-γ can upregulate the effect of LPS at the level of transcription. Human monoblastic Mono-Mac-6 cells produced up to threefold-greater levels of TNF-α when simultaneously stimulated with LPS and IFN-γ compared to treatment with LPS alone. RNase protection studies showed a similar increase in RNA beginning as early as within 30 min. The synthesis of TNF-α mRNA in IFN-γ- and LPS-treated Mono-Mac-6 cells was also temporally prolonged even though the message turnover rate was identical to that seen in LPS stimulated cells. The modulatory effect of IFN-γ may be mediated by Jak2.

scholarly journals Gene Expression and Production of Tumor Necrosis Factor Alpha, Interleukin-1β (IL-1β), IL-8, Macrophage Inflammatory Protein 1α (MIP-1α), MIP-1β, and Gamma Interferon-Inducible Protein 10 by Human Neutrophils Stimulated with Group B Meningococcal Outer Membrane Vesicles

2000 ◽  
Vol 68 (12) ◽  
pp. 6917-6923 ◽  
Author(s):  
José A. Lapinet ◽  
Patrizia Scapini ◽  
Federica Calzetti ◽  
Oliver Pérez ◽  
Marco A. Cassatella
Keyword(s):  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Necrosis Factor Alpha ◽  
Cytokines And Chemokines ◽  
Inflammatory Protein ◽  
Tnf Α ◽  
Factor Alpha ◽  
Ifn Γ ◽  
Inducible Protein ◽  
Necrosis Factor

ABSTRACT Accumulation of polymorphonuclear neutrophils (PMN) into the subarachnoidal space is one of the hallmarks of Neisseria meningitidis infection. In this study, we evaluated the ability of outer membrane vesicles (OMV) from N. meningitidis B to stimulate cytokine production by neutrophils. We found that PMN stimulated in vitro by OMV produce proinflammatory cytokines and chemokines including tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-8, macrophage inflammatory protein 1α (MIP-1α), and MIP-1β. A considerable induction of gamma interferon (IFN-γ)-inducible protein 10 (IP-10) mRNA transcripts, as well as extracellular IP-10 release, was also observed when neutrophils were stimulated by OMV in combination with IFN-γ. Furthermore, PMN stimulated by OMV in the presence of IFN-γ demonstrated an enhanced capacity to release TNF-α, IL-1β, IL-8, and MIP-1β compared to stimulation with OMV alone. In line with its downregulatory effects on neutrophil-derived proinflammatory cytokines, IL-10 potently inhibited TNF-α, IL-1β, IL-8, and MIP-1β production triggered by OMV. Finally, a neutralizing anti-TNF-α monoclonal antibody (MAb) did not influence the release of IL-8 and MIP-1β induced by OMV, therefore excluding a role for endogenous TNF-α in mediating the induction of chemokine release by OMV. In contrast, the ability of lipopolysaccharide fromN. meningitidis B to induce the production of IL-8 and MIP-1β was significantly inhibited by anti-TNF-α MAb. Our results establish that, in response to OMV, neutrophils produce a proinflammatory profile of cytokines and chemokines which may not only play a role in the pathogenesis of meningitis but may also contribute to the development of protective immunity to serogroup B meningococci.

scholarly journals Dynamic Changes in Pro- and Anti-Inflammatory Cytokine Profiles and Gamma Interferon Receptor Signaling Integrity Correlate with Tuberculosis Disease Activity and Response to Curative Treatment

2006 ◽  
Vol 75 (2) ◽  
pp. 820-829 ◽  
Author(s):  
Edhyana Sahiratmadja ◽  
Bachti Alisjahbana ◽  
Tjitske de Boer ◽  
Iskandar Adnan ◽  
Anugrah Maya ◽  
...  
Keyword(s):  
Disease Activity ◽  
Disease Severity ◽  
Mycobacterial Infection ◽  
Gamma Interferon ◽  
Interleukin 12 ◽  
Dynamic Changes ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Ifn Γ ◽  
Anti Inflammatory

ABSTRACT Pro- and anti-inflammatory cytokines and their signaling pathways play key roles in protection from and pathogenesis of mycobacterial infection, and their balance and dynamic changes may control or predict clinical outcome. Peripheral blood cells' capacity to produce proinflammatory (tumor necrosis factor alpha [TNF-α], interleukin-12/23p40 [IL-12/23p40], and gamma interferon [IFN-γ]) and anti-inflammatory (IL-10) cytokines in response to Mycobacterium tuberculosis or unrelated stimuli (lipopolysaccharide, phytohemagglutinin) was studied in 93 pulmonary tuberculosis (TB) patients and 127 healthy controls from Indonesia. Their cells' ability to respond to IFN-γ was examined to investigate whether M. tuberculosis infection can also inhibit IFN-γ receptor (IFN-γR) signaling. Although there was interindividual variability in the observed responses, the overall results revealed that M. tuberculosis-induced TNF-α and IFN-γ levels showed opposite trends. Whereas TNF-α production was higher in active-TB patients than in controls, IFN-γ production was strongly depressed during active TB, correlated inversely with TB disease severity, and increased during therapy. By contrast, mitogen-induced IFN-γ production, although lower in patients than in controls, did not change during treatment, suggesting an M. tuberculosis-specific and reversible component in the depression of IFN-γ. Depressed IFN-γ production was not due to decreased IL-12/IL-23 production. Importantly, IFN-γ-inducible responses were also significantly depressed during active TB and normalized during treatment, revealing disease activity-related and reversible impairment in IFN-γR signaling in TB. Finally, IFN-γ/IL-10 ratios significantly correlated with TB cure. Taken together, these results show that M. tuberculosis-specific stimulation of IFN-γ (but not TNF-α) production and IFN-γR signaling are significantly depressed in active TB, correlate with TB disease severity and activity, and normalize during microbiological TB cure. The depression of both IFN-γ production and IFN-γR signaling may synergize in contributing to defective host control in active TB.

scholarly journals Discrimination between Active and Latent Tuberculosis Based on Ratio of Antigen-Specific to Mitogen-Induced IP-10 Production

2014 ◽  
Vol 53 (2) ◽  
pp. 504-510 ◽  
Author(s):  
Yun Hee Jeong ◽  
Yun-Gyoung Hur ◽  
Hyejon Lee ◽  
Sunghyun Kim ◽  
Jang-Eun Cho ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Interleukin 2 ◽  
Induced Responses ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Monocyte Chemoattractant Protein 1 ◽  
Tnf Α ◽  
Release Assay ◽  
Ltbi Group ◽  
Ifn Γ

Mycobacterium tuberculosisis the major causative agent of tuberculosis (TB). The gamma interferon (IFN-γ) release assay (IGRA) has been widely used to diagnose TB by testing cell-mediated immune responses but has no capacity for distinguishing between active TB and latent TB infection (LTBI). This study aims to identify a parameter that will help to discriminate active TB and LTBI. Whole-blood samples from 33 active TB patients, 20 individuals with LTBI, and 26 non-TB controls were applied to the commercial IFN-γ release assay, QuantiFERON-TB Gold In-Tube, and plasma samples were analyzed for interleukin-2 (IL-2), IL-6, IL-8, IL-10, IL-13, tumor necrosis factor-alpha (TNF-α), IFN-γ, monokine induced by IFN-γ (MIG), interferon gamma inducible protein 10 (IP-10), interferon-inducible T cell alpha chemoattractant (I-TAC), and monocyte chemoattractant protein 1 (MCP-1) by using a commercial cytometric bead array. TheMycobacterium tuberculosisantigen-specific production of most of the assayed cytokines and chemokines was higher in the active TB than in the LTBI group. The mitogen-induced responses were lower in the active TB than in the LTBI group. When the ratio of TB-specific to mitogen-induced responses was calculated, IL-2, IL-6, IL-10, IL-13, TNF-α, IFN-γ, MIG, and IP-10 were more useful in discriminating active TB from LTBI. In particular, most patients showed higher IP-10 production toMycobacterium tuberculosisantigens than to mitogen at the individual level, and the ratio for IP-10 was the strongest indicator of active infection versus LTBI with 93.9% sensitivity and 90% specificity. In conclusion, the ratio of the TB-specific to the mitogen-induced IP-10 responses showed the most promising accuracy for discriminating active TB versus LTBI and should be further studied to determine whether it can serve as a biomarker that might help clinicians administer appropriate treatments.

scholarly journals Interleukin-12 Promotes Gamma Interferon-Dependent Neutrophil Recruitment in the Lung and Improves Protection against Respiratory Streptococcus pneumoniae Infection

2007 ◽  
Vol 75 (3) ◽  
pp. 1196-1202 ◽  
Author(s):  
Keer Sun ◽  
Sharon L. Salmon ◽  
Steven A. Lotz ◽  
Dennis W. Metzger
Keyword(s):  
Streptococcus Pneumoniae ◽  
Survival Rates ◽  
Gamma Interferon ◽  
Neutrophil Recruitment ◽  
Interleukin 12 ◽  
Necrosis Factor Alpha ◽  
Innate Defense ◽  
Tnf Α ◽  
Ifn Γ

ABSTRACT The ability of exogenous interleukin-12 (IL-12) to elicit protective innate immune responses against the extracellular pathogen Streptococcus pneumoniae was tested by infecting BALB/c mice intranasally (i.n.) with S. pneumoniae after i.n. administration of IL-12. It was found that administration of IL-12 resulted in lower bacterial burdens in the infected mice and significantly improved survival rates. All IL-12-treated mice contained higher levels of pulmonary gamma interferon (IFN-γ) after infection and significantly more neutrophils than infected mice not treated with IL-12. IFN-γ was found to be essential for IL-12-induced resistance and for neutrophil influx into the lungs, and the observed changes correlated with increased levels of the IL-8 homologue keratinocyte-derived chemokine (KC). In addition, in vitro tumor necrosis factor alpha (TNF-α) production by alveolar macrophages stimulated with heat-killed pneumococci was enhanced by IFN-γ, and TNF-α in turn could enhance production of KC by lung cells. Finally, IL-12-induced protection was dependent upon the presence of neutrophils and the KC receptor CXCR2. Taken together, the results indicate that exogenous IL-12 can improve innate defense in the lung against S. pneumoniae by inducing IFN-γ production, which in turn enhances chemokine expression, and promotes pulmonary neutrophil recruitment into the infected lung. The findings show that IL-12 and IFN-γ can mediate a protective effect against respiratory infection caused by extracellular bacterial pathogens.

scholarly journals CD40 Restrains In Vivo Growth of Toxoplasma gondii Independently of Gamma Interferon

2006 ◽  
Vol 74 (3) ◽  
pp. 1573-1579 ◽  
Author(s):  
Carlos S. Subauste ◽  
Matthew Wessendarp
Keyword(s):  
Toxoplasma Gondii ◽  
Parasite Load ◽  
Gamma Interferon ◽  
Cd40 Ligation ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Cd40 Stimulation ◽  
Ifn Γ ◽  
In Vivo Growth

ABSTRACT CD40-CD154 interaction is pivotal for resistance against numerous pathogens. However, it is not known if this pathway can also enhance in vivo resistance in gamma interferon (IFN-γ)-deficient hosts. This is an important question because patients and mice with defects in type 1 cytokine response can control a variety of pathogens. While blockade of endogenous CD154 resulted in a remarkable increase in parasite load in IFN-γ−/− mice infected with Toxoplasma gondii, in vivo administration of a stimulatory anti-CD40 monoclonal antibody markedly reduced parasite load. This latter effect took place even in T-cell-depleted mice and was accompanied by induction of macrophage toxoplasmacidal activity. CD40 stimulation restricted T. gondii replication independently of STAT1, p47 GTPases, and nitric oxide. In vivo CD40 ligation enhanced tumor necrosis factor alpha (TNF-α) production by T. gondii-infected macrophages. In addition, CD40 stimulation required the presence of TNF receptor 2 to reduce parasite load in vivo. These results suggest that CD40-CD154 interaction regulates IFN-γ-independent mechanisms of host protection through induction of macrophage antimicrobial activity and modulation of TNF-α signaling.

scholarly journals Regulatory Effects of Macrophage Inflammatory Protein 1α/CCL3 on the Development of Immunity to Cryptococcus neoformans Depend on Expression of Early Inflammatory Cytokines

2001 ◽  
Vol 69 (10) ◽  
pp. 6256-6263 ◽  
Author(s):  
Michal A. Olszewski ◽  
Gary B. Huffnagle ◽  
Timothy R. Traynor ◽  
Roderick A. McDonald ◽  
Donald N. Cook ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Inflammatory Cytokines ◽  
Virulent Strain ◽  
Innate Immune ◽  
Necrosis Factor Alpha ◽  
Inflammatory Protein ◽  
Tnf Α ◽  
Ifn Γ ◽  
The Brain ◽  
Macrophage Inflammatory Protein

ABSTRACT Macrophage inflammatory protein 1α (MIP-1α)/CCL3 prevents the development of eosinophilic pneumonia (EP) driven by a nonprotective T2-type immunity during infection with a highly virulent strain ofCryptococcus neoformans. The present study evaluated the interaction of MIP-1α with other innate immune system cytokines by comparing the immune responses that followed pulmonary infections with high- (C. neoformans 145A) and low (C. neoformans 52D)-virulence strains. In contrast to what was found for C. neoformans 145A infection, lack of MIP-1α in C. neoformans 52D infection did not cause the development of EP. C. neoformans 52D induced tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and MCP-1 in the lungs of infected wild-type (WT) and MIP-1α knockout (KO) mice by day 7 postinfection. Both WT and MIP-1α KO mice subsequently cleared this infection. Thus, the robust expression of early inflammatory cytokines in C. neoformans 52D-infected mice promoted the development of protective immunity even in the absence of MIP-1α. Alternatively, C. neoformans145A-infected WT and MIP-1α KO mice had diminished TNF-α, IFN-γ, and macrophage chemoattractant protein 1 (MCP-1) responses, indicating that virulent C. neoformans 145A evaded early innate host defenses. However C. neoformans145A-infected WT mice had an early induction of MIP-1α and subsequently did not develop EP. In contrast, C. neoformans 145A-infected MIP-1α KO mice developed EP and had increased C. neoformans dissemination into the brain by day 35. We conclude that, in the absence of other innate immune response effector molecules, MIP-1α is crucial to prevent the development of EP and to control C. neoformansdissemination to the brain.

scholarly journals Up-Regulation of Gamma Interferon Receptor Expression Due to Chlamydia-Toll-Like Receptor Interaction Does Not Enhance Signal Transducer and Activator of Transcription 1 Signaling

2006 ◽  
Vol 74 (12) ◽  
pp. 6877-6884 ◽  
Author(s):  
Kari Ann Shirey ◽  
Joo-Yong Jung ◽  
Joseph M. Carlin
Keyword(s):  
Adaptor Protein ◽  
Gamma Interferon ◽  
Chlamydia Psittaci ◽  
Receptor Expression ◽  
Receptor Interaction ◽  
Signal Transducer ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Infected Cells ◽  
Ifn Γ

ABSTRACT Gamma interferon (IFN-γ)-induced indoleamine dioxygenase (IDO), which inhibits chlamydial replication by reducing the availability of tryptophan, is up-regulated by interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α). The mechanisms by which this occurs include an increase in the synthesis of interferon regulatory factor-1 as well as a nuclear factor-κB (NF-κB)-dependent increase in the expression of IFN-γ receptors (IFN-γR). Although Chlamydia is susceptible to IDO, it up-regulates IFN-γR expression to a greater degree than either IL-1β or TNF-α, perhaps through interaction with Toll-like receptors (TLR). The purpose of this study was to determine the mechanism by which Chlamydia psittaci up-regulates IFN-γR expression and evaluate this effect on IDO induction. Infection of HEK 293 cells with C. psittaci increased IFN-γR expression only in cells expressing either TLR2 or TLR4 and the adaptor protein MD-2. In addition, up-regulation of IFN-γR expression in Chlamydia-infected HeLa cells could be blocked either by neutralizing TLRs with anti-TLR2 and/or anti-TLR4 or by inhibiting NF-κB transactivation with a proteasome inhibitor. Although the newly expressed IFN-γR in Chlamydia-infected cells were capable of binding IFN-γ, they did not enhance IFN-γ-induced IDO activity in a manner similar to those observed for IL-1β and TNF-α. Instead, IDO activation in Chlamydia-infected cells was no different than that induced in uninfected cells, despite the increase in IFN-γR expression. Furthermore, the amount of IFN-γ-induced signal transducer and activator of transcription 1 (STAT-1) activation in infected cells paralleled that observed in uninfected cells, suggesting that STAT-1 activation by these newly expressed receptors was impaired.

scholarly journals Increased Pulmonary Tumor Necrosis Factor Alpha, Interleukin-6 (IL-6), and IL-17A Responses Compensate for Decreased Gamma Interferon Production in Anti-IL-12 Autovaccine-Treated,Mycobacterium bovisBCG-Vaccinated Mice

2010 ◽  
Vol 18 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Danielle Freches ◽  
Marta Romano ◽  
Hannelie Korf ◽  
Jean-Christophe Renauld ◽  
Jacques Van Snick ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Gamma Interferon ◽  
Enzyme Linked Immunosorbent Assay ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Factor Alpha ◽  
Ifn Γ ◽  
Necrosis Factor

ABSTRACTInterleukin-12 (IL-12) and IL-23 (which share a p40 subunit) are pivotal cytokines in the generation of protective Th1/Th17-type immune responses upon infection with the intracellular pathogenMycobacterium tuberculosis. The role of IL-12 and IL-23 in protection conferred by the tuberculosis vaccineMycobacterium bovisbacillus Calmette-Guérin (BCG) is, however, less well documented. By using an autovaccine approach, i.e., IL-12p70 cross-linked with ovalbumin and PADRE peptide formulated with the GSK proprietary adjuvant system AS02V, we could specifically neutralize IL-12 while leaving the IL-23 axis intact. Neutralization of IL-12 beforeM. tuberculosischallenge rendered C57BL/6 mice highly susceptible, resulting in 30-fold-higher CFU in spleen and lungs and accelerated mortality. In contrast, neutralization of IL-12 in BCG-vaccinated mice prior toM. tuberculosischallenge only marginally affected vaccine-mediated protection. Analysis of cytokine production in spleen and lungs 3 weeks post-TB challenge by enzyme-linked immunosorbent assay and functional and flow cytometric assays showed significantly reduced mycobacterium-specific gamma interferon (IFN-γ) responses inM. tuberculosis-infected and BCG-vaccinated mice that had been treated with the autovaccine. Purified protein derivative-induced tumor necrosis factor alpha (TNF-α), IL-6, and IL-17A levels, however, were highest in lungs from BCG-vaccinated/IL-12-neutralized animals, and even unstimulated lung cells from these mice produced significant levels of the three cytokines. Mycobacterium-specific IL-4 and IL-5 production levels were overall very low, but IL-12 neutralization resulted in increased concanavalin A-triggered polyclonal secretion of these Th2-type cytokines. These results suggest that TNF-α, IL-6, and IL-17A may be more important pulmonary effector molecules of BCG-mediated protection than IFN-γ in a context of IL-12 deficiency.

scholarly journals Granulocyte-Macrophage Colony-Stimulating Factor-Deficient Mice Have Impaired Resistance to Blood-Stage Malaria

2001 ◽  
Vol 69 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Julie Riopel ◽  
MiFong Tam ◽  
Karkada Mohan ◽  
Michael W. Marino ◽  
Mary M. Stevenson
Keyword(s):  
Blood Stage ◽  
Colony Stimulating Factor ◽  
Necrosis Factor Alpha ◽  
Gm Csf ◽  
Tnf Α ◽  
Macrophage Colony Stimulating Factor ◽  
Ifn Γ ◽  
Macrophage Colony ◽  
Stimulating Factor ◽  
Blood Stage Malaria

ABSTRACT The contribution of granulocyte-macrophage colony-stimulating factor (GM-CSF), a hematopoietic and immunoregulatory cytokine, to resistance to blood-stage malaria was investigated by infecting GM-CSF-deficient (knockout [KO]) mice with Plasmodium chabaudi AS. KO mice were more susceptible to infection than wild-type (WT) mice, as evidenced by higher peak parasitemia, recurrent recrudescent parasitemia, and high mortality. P. chabaudiAS-infected KO mice had impaired splenomegaly and lower leukocytosis but equivalent levels of anemia compared to infected WT mice. Both bone marrow and splenic erythropoiesis were normal in infected KO mice. However, granulocyte-macrophage colony formation was significantly decreased in these tissues of uninfected and infected KO mice, and the numbers of macrophages in the spleen and peritoneal cavity were significantly lower than in infected WT mice. Serum levels of gamma interferon (IFN-γ) were found to be significantly higher in uninfected KO mice, and the level of this cytokine was not increased during infection. In contrast, IFN-γ levels were significantly above normal levels in infected WT mice. During infection, tumor necrosis factor alpha (TNF-α) levels were significantly increased in KO mice and were significantly higher than TNF-α levels in infected WT mice. Our results indicate that GM-CSF contributes to resistance to P. chabaudi AS infection and that it is involved in the development of splenomegaly, leukocytosis, and granulocyte-macrophage hematopoiesis. GM-CSF may also regulate IFN-γ and TNF-α production and activity in response to infection. The abnormal responses seen in infected KO mice may be due to the lack of GM-CSF during development, to the lack of GM-CSF in the infected mature mice, or to both.

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