Intact Immunity Research Articles

Dual Therapeutic Efficacy of Vinblastine as a Unique Chemotherapeutic Agent Capable of Inducing Dendritic Cell Maturation

Our recent unbiased functional screen of 54 chemotherapeutic drugs unveiled striking heterogeneity in their effects on dendritic cells (DC). Most notably, vinblastine (VBL) was found to induce phenotypic and functional maturation of DCs in vitro. Here, we sought to determine whether VBL exhibits "dual" therapeutic efficacy in living animals by directly killing tumor cells and by boosting host immunity via DC maturation. Local injection of VBL in a low dose into the skin of C57BL/6 mice induced in situ maturation of epidermal Langerhans cells. When coinjected with a model antigen, ovalbumin (OVA), VBL enhanced OVA-specific cellular and humoral immune responses. When injected directly into the OVA cDNA-transduced E.G7 tumors, VBL augmented clonal expansion of OVA-reactive CD8 T cells and CTL activities. In B16 melanoma model, intratumor VBL injection induced apoptosis of melanoma cells, phenotypic maturation of tumor-infiltrating DCs, and significant CTL activities. Although complete clearance was never achieved, growth kinetic of B16 melanoma was markedly reduced in C57BL/6 mice by intratumor VBL injection. Importantly, the same treatment was far less efficacious in immunocompromised severe combined immunodeficient mice, indicating the requirement of intact host immunity. Our results introduce a new concept that VBL may be used to design "immunostimulatory" chemotherapy regimens.

Distinct Responses of Human Monocyte Subsets to Aspergillus fumigatus Conidia

Aspergillus fumigatus is an environmental fungus that causes life-threatening infections in neutropenic patients. In the absence of intact innate immunity, inhaled A. fumigatus spores (conidia) germinate in the lung, forming hyphae that invade blood vessels and disseminate to other tissues. Although macrophages and neutrophils are postulated to provide defense against invasive fungal infection, animal models and human studies suggest that circulating monocytes also contribute to antifungal immunity. Although human monocyte subsets, defined as either CD14(+)CD16(-) or CD14(+)CD16(+), have been extensively characterized, their respective roles during fungal infection remain undefined. We isolated CD14(+)CD16(-) and CD14(+)CD16(+) monocytes from healthy allogeneic hematopoietic stem cell transplantation donors and compared their ability to phagocytose and inhibit A. fumigatus conidia. Both monocyte subsets efficiently phagocytose conidia, but only CD14(+)CD16(-) monocytes inhibit conidial germination yet secrete little TNF. In contrast CD14(+)CD16(+) do not inhibit conidial germination and secrete large amounts of TNF. Although CD14(+)CD16(-) and CD14(+)CD16(+) monocytes differ in their response to dormant conidia, responses are similar if conidia are already germinated at the time of monocyte uptake. Our study demonstrates that functional CD14(+)CD16(-) and CD14(+)CD16(+) monocytes can be isolated from allogeneic hematopoietic stem cell transplantation donors and that these subsets differ in their response to A. fumigatus conidia.

The Health Impact of Supportive Housing for HIV-Positive Homeless Patients: A Randomized Controlled Trial

We assessed the health impact of a housing and case management program, the Chicago Housing for Health Partnership, for homeless people with HIV. HIV-positive homeless inpatients at a public hospital (n = 105) were randomized to usual care or permanent housing with intensive case management. The primary outcome was survival with intact immunity, defined as CD4 count > or = 200 and viral load < 100,000. Secondary outcomes were viral loads, undetectable viral loads, and CD4 counts. Outcomes were available for 94 of 105 enrollees (90%). Of 54 intervention participants, 35 (65%) reached permanent housing in program housing agencies. After 1 year, 55% of the intervention and 34% of the usual care groups were alive and had intact immunity (P = .04). Seventeen intervention (36%) and 9 usual care (19%) participants had undetectable viral loads (P = .051). Median viral loads were 0.89 log lower in the intervention group (P = .03). There were no statistical differences in CD4 counts. Homelessness is a strong predictor of poor health outcomes and complicates the medical management of HIV. This housing intervention improved the health of HIV-positive homeless people.

Children with endemic Burkitt lymphoma are deficient in EBNA1‐specific IFN‐γ T cell responses

Endemic Burkitt lymphoma (eBL) is the most common childhood cancer in equatorial Africa and is linked to Epstein-Barr virus (EBV) and Plasmodium falciparum coinfections early in life. Epstein-Barr nuclear antigen 1 (EBNA1) is the sole viral latent antigen expressed in BL tumors. Loss of EBNA1-specific immune surveillance could allow eBL emergence. Therefore, EBNA1-specific T cell responses were analyzed by IFN-gamma ELISPOT in Kenyan children with eBL and compared to healthy children with divergent malaria exposure. Significantly fewer children with eBL, 16% (7/44) had EBNA1-specific IFN-gamma responses in contrast to healthy children living in a malaria holoendemic area or in an area with sporadic malaria transmission, 67% (40/60) and 72% (43/60) responders, respectively (p < 0.003). Children with eBL maintained IgG(1) dominated antibody responses to EBNA1 similar to healthy children suggesting a selective loss of IFN-gamma secreting EBNA1-specific T cells in the presence of intact humoral immunity. CD8(+) T cell responses to EBV lytic and latent antigens not expressed in the tumors were similarly robust in eBL patients compared to healthy children. In addition, CD4(+) T cell responses to a malaria protein, merozoite surface protein 1, were present in lymphoma patients. This study demonstrates a selective loss of EBNA1-specific T cell responses in children with eBL and suggests a potential immunotherapeutic target for this EBV-associated lymphoma.

Interaction of human papillomaviruses with the host immune system: A well evolved relationship

Human papillomavirus (HPV) infections are generally long lasting, and a host immune response to infection is hard to detect. Nevertheless immunocompromised subjects control HPV infection less well than those with intact immunity. Immune responses are best documented for the papillomavirus groups that cause evident human disease, particularly those responsible for anogenital cancers and genital warts. Humoral immunity to the viral capsid has been shown sufficient for protection against infection, while innate and adaptive cell mediated immunity appears important for eventual elimination of HPV infection. However, molecular and cellular mechanisms responsible for protection from and clearance of HPV infection are not completely established.

Use of mefloquine in multidrug-resistant Mycobacterium avium complex pulmonary disease in an HIV-negative patient

Mycobacterium avium complex (MAC) is a leading cause of pulmonary disease (PD), even in those with intact immunity, representing about 30% of the cases of pleuropulmonary mycobacterial infection. Based on previous studies, macrolides are the only agents used in the treatment of MAC disease for which there is a correlation between in vitro susceptibility and in vivo (clinical) response. However, resistance develops rapidly if single-agent treatment is used. Data regarding treatment of macrolide-resistant MAC (MRMAC) and multidrug-resistant MAC (MDRMAC) are sparse. A 50-year-old, HIV-negative white man, weighing 53.6 kg, with severe chronic obstructive pulmonary disease and bronchiectasis was initially on treatment for MAC-PD and MRMAC. The patient was followed between 1999 and 2006. His treatment history revealed that in addition to the multiple drugs administered during the course of his illness, thalidomide, interferon-γ, and mefloquine were also administered. The patient died ~7 years later due to respiratory failure and overwhelming infection This case report describes the use of mefloquine as adjunct treatment in an HIV-negative patient with MDRMAC-PD and discusses the associated outcomes of drug resistance.

Ozone and Pulmonary Innate Immunity

Ambient ozone (O(3)) is a commonly encountered environmental air pollutant with considerable impact on public health. Many other inhaled environmental toxicants can substantially affect pulmonary immune responses. Therefore, it is of considerable interest to better understand the complex interaction between environmental airway irritants and immunologically based human disease. The innate immune system represents the first line of defense against microbial pathogens. Intact innate immunity requires maintenance of an intact barrier to interface with the external environment, effective phagocytosis of microbial pathogens, and precise detection of pathogen-associated molecular patterns. We use ambient O(3) as a model to highlight the importance of understanding the role of exposure to ubiquitous air toxins and regulation of basic immune function. Inhalation of O(3) is associated with impaired antibacterial host defense, in part related to disruption of epithelial barrier and effective phagocytosis of pathogens. The functional response to ambient O(3) seems to be dependent on many components of the innate immune signaling. In this article, we review the complex interaction between inhalation of O(3) and pulmonary innate immunity.

Arhgef1 Is Required by T Cells for the Development of Airway Hyperreactivity and Inflammation

Arhgef1 is an intracellular protein, expressed by hematopoietic cells, that regulates signaling by both G protein-coupled receptors and RhoA, and, consequently, is required for appropriate migration and adhesion of diverse leukocyte populations. To evaluate a possible contribution for Arhgef1 in the development of airway inflammation and airway hyperreactivity. Arhgef1-deficient (Arhgef1-/-) and wild-type (WT) mice were sensitized and airway challenged, followed by measurement of airway responsiveness to inhaled methacholine. Inflammation was assessed by several parameters that included flow cytometric analysis and histology. Arhgef1-deficient recipients were reconstituted with WT T lymphocytes before sensitization and challenge, and again measured for airway responsiveness and inflammation. Cytokine production in response to specific antigen was measured in cultures of isolated leukocytes from lung and spleen and compared with the levels generated in lung and spleen explant cultures. Arhgef1-/- mice display significantly reduced airway hyperreactivity, Th2 cytokine production, and lung inflammation, despite intact systemic immunity. After airway challenge of Arhgef1-/- mice, antigen-specific T cells were present in mutant lungs, but were found to interact with CD11c+ cells at a significantly reduced frequency. Adoptive transfer of WT T cells into Arhgef1-/- mice restored airway hyperreactivity and inflammation. These data demonstrate that T cells depend on Arhgef1 to promote lung inflammation. Moreover, a deficiency in Arhgef1 results in reduced T cell-CD11c+ antigen-presenting cell interaction, and likely underscores the inability of Arhgef1-/- mice to mount an adaptive immune response to airway challenge.

Parenteral Nutrition Impairs Gut-Associated Lymphoid Tissue and Mucosal Immunity by Reducing Lymphotoxin β Receptor Expression

To determine the effects of parenteral nutrition (PN) on LTbetaR in gut-associated lymphoid tissue (GALT), particularly the intestine and Peyer's patches (PP). Lack of enteral stimulation with PN impairs mucosal immunity and reduces IgA levels through depression of GALT cytokines (IL-4 and IL-10) and GALT specific adhesion molecules. We have shown that each is critical to intact mucosal immunity through effects on lymphocyte homing, IgA production, and resistance to antibacterial and antiviral immunity. IgA is the principal specific immunologic mucosal defense. LTbetaR stimulation controls production of IL-4, the adhesion molecule MAdCAM-1, and other key components of GALT, all of which are important in increasing IgA levels and maintaining mucosal defenses. Experiment 1: LTbetaR expression in intestine and PP was analyzed by Western blot after 5 days of chow, a complex enteral diet (CED), or PN. Diets were isocaloric and isonitrogenous except for chow. Experiment 2: After completing pilot experiments to determine the appropriate dose of the LTbetaR agonistic antibody, mice received chow, PN + 5 mug of anti-LTbetaR mAb (2 times/d, i.v.) or PN + isotype control antibody. PP lymphocytes and intestinal IgA levels were measured after 2 days. Lack of enteral stimulation with PN significantly decreased LTbetaR expression in intestine and PP compared with chow and CED. LTbetaR stimulation with an agonistic anti-LTbetaR mAb significantly increased PP lymphocyte counts and intestinal IgA in PN fed-mice. LTbetaR expression is critical for GALT control mechanisms and intact mucosal immunity. PN reduces LTbetaR expression, PP lymphocytes, and intestinal IgA production. Exogenous LTbetaR stimulation reverses PN-induced depression of gut mucosal immunity.

Letters to the Editor

Letters to the Editor

Mycobacterium avium Complex Pulmonary Disease in Immunocompetent Patients

Mycobacterium avium complex is becoming increasingly recognized as one of the most common mycobacterial pathogens in humans. It is rapidly becoming a significant cause of pulmonary disease even in those with an intact immunity. In 1997, the American Thoracic Society published recommendations for the diagnosis and treatment of nontuberculous mycobacteria. On the basis of the authors' clinical experience of the myriad presentations of pulmonary Mycobacterium avium complex disease in an immunocompetent host, a clinical classification is proposed. The current data are summarized, and a practical approach to management of the various pulmonary forms of the disease is provided.

IFN-γ at the Site of Infection Determines Rate of Clearance of Infection in Cryptococcal Meningitis

In animal models, immunity to cryptococcal infection, as in many chronic fungal and bacterial infections, is associated with a granulomatous inflammatory response, intact cell-mediated immunity, and a Th1 pattern of cytokine release. To examine the correlates of human immunity to cryptococcal infection in vivo, we analyzed immune parameters at the site of infection over time and assessed the rate of clearance of infection by serial quantitative cerebrospinal fluid (CSF) fungal cultures in 62 patients in a trial of antifungal therapy for HIV-associated cryptococcal meningitis. CSF IL-6, IFN-gamma, TNF-alpha, and IL-8 were significantly higher in survivors compared with nonsurvivors. There were negative correlations between log TNF-alpha, IFN-gamma, and IL-6 levels and baseline cryptococcal CFU. Log IFN-gamma, G-CSF, TNF-alpha, and IL-6 were correlated positively with the rate of fall in log CFU/ml CSF/day. In a linear regression model including antifungal treatment group, baseline CFU, and these cytokines, only treatment group and log IFN-gamma remained independently associated with rate of clearance of infection. The results provide direct in vivo evidence for the importance of quantitative differences in IFN-gamma secretion in human immune control of granulomatous infections, and increase the rationale for adjunctive IFN-gamma in the treatment of refractory HIV-associated cryptococcosis.

Rapamycin and tumor growth: mechanisms behind its anticancer activity

In the past few years, a heightened awareness has developed toward the problem of cancer occurrence and treatment in organ transplant recipients under immunosuppression. Treatment and prevention of cancer in transplant patients with an intentionally suppressed immune system are generally not considered an ideal situation because intact immunity is important for recognizing and destroying potentially neoplastic cells. Nonetheless, recent studies indicate that fighting tumors is not impossible under conditions of immune suppression, and in fact, immunosuppressive agents have been discovered that possess potent anticancer effects. In particular, one class of immunosuppressants, referred to as mammalian target of rapamycin (mTOR) inhibitors (mTORi), has experimentally shown an ability to suppress the immune system to protect allografts from rejection while simultaneously inhibiting tumor growth. To gain a better understanding of this dual effect, we will review the key intracellular signaling pathways controlled by mTOR. We will discuss how mTORi affects the growth and survival of a variety of nonimmune cells, with a special emphasis on cancer. A better understanding of mTOR-related pathways and the repertoire of normal and neoplastic cells affected by mTORi will likely improve our ability to treat transplant rejection, cancer, and other pathological conditions.

Gene expression profiling in murine autoimmune arthritis during the initiation and progression of joint inflammation

We present here an extensive study of differential gene expression in the initiation, acute and chronic phases of murine autoimmune arthritis with the use of high-density oligonucleotide arrays interrogating the entire mouse genome. Arthritis was induced in severe combined immunodeficient mice by using adoptive transfer of lymphocytes from proteoglycan-immunized arthritic BALB/c mice. In this unique system only proteoglycan-specific lymphocytes are transferred from arthritic mice into syngeneic immunodeficient recipients that lack adaptive immunity but have intact innate immunity on an identical (BALB/c) genetic background.Differential gene expression in response to donor lymphocytes that migrated into the joint can therefore be monitored in a precisely timed manner, even before the onset of inflammation. The initiation phase of adoptively transferred disease (several days before the onset of joint swelling) was characterized by differential expression of 37 genes, mostly related to chemokines, interferon-γ and tumor necrosis factor-α signaling, and T cell functions. These were designated early arthritis 'signature' genes because they could distinguish between the naive and the pre-arthritic state. Acute joint inflammation was characterized by at least twofold overexpression of 256 genes and the downregulation of 21 genes, whereas in chronic arthritis a total of 418 genes with an equal proportion of upregulated and downregulated transcripts were expressed differentially.Hierarchical clustering and functional classification of inflammation-related and arthritis-related genes indicated that the most common biological activities were represented by genes encoding interleukins, chemokine receptors and ligands, and by those involved in antigen recognition and processing.

Transient hypogammaglobulinemia of infancy; analysis and follow-up

Rationale Transient Hypogammaglobulinemia of Infancy is considered a primary immune deficiency, but is not well defined, and long term follow-up not reported. The purpose of this study is to: 1) Characterize infants with recurrent infections and low immunoglobulins 2) Provide long-term follow-up. Methods Forty-two patients were evaluated between 1977-2003 who: 1) Were younger than 24 months, 2) Had one or more immunoglobulin classes 2 SD below normal means, 3) Produced antibody normally to diphtheria and tetanus, 4) Had evidence of intact cell mediated immunity, and 5) Lacked features of other immunodeficiency syndromes. The following were collected: Quantitative immunoglobulins at presentation and follow-up, recurrent infection information, atopic development, age at presentation and immunoglobulin normalization, sex, and gender. Results 1) Infants were 27/42 (64%) male. 2) At presentation, immunoglobulins showed decreased: IgA (95%), IgG (74%), then IgM (5%). 3) OM's, bronchitis, or both in 88%. Other infections were: thrush, pneumonia, and bacteremia. 4) 43% of study patients developed atopy. 5) Infections decreased as age increased. 6) Not all immunoglobulins normalized during observation. All with IgM deficiency normalized by age 3 years, but 80% had low IgA and 10% low IgG at 6-11 years and 2 children had selective IgA deficiency. Conclusions Infants who present exclusively with diminished immunoglobulins without other immunologic abnormalities are predominantly male and suffer from recurrent infections. With age, the frequency and severity of infections decrease as immunoglobulins normalize, but, many develop atopy and some IgA deficiency. Children with THI represent a heterogeneous group whose immunogical outcome varies. Close monitoring is indicated.

Tetanus antitoxin seroprevalence in patients with Behçet's disease.

Anti-tetanus antibody status was evaluated by enzyme-linked immunosorbent assay in 82 patients with Behçet's disease and 79 healthy individuals. 76 patients with Behçet's disease (92.7%) and 74 healthy controls (93.7%) had protective antibody titres against tetanus, with geometric mean levels of 1.0194 +/- 1.2755 and 1.3899 +/- 1.6533 IU/ml, respectively. The difference between the 2 groups was not statistically significant. There was a significant inverse correlation between antitoxin titres and age in patient and control groups. These findings imply that patients with Behçet's disease have intact overall immunity against tetanus.

Role of leptin in immunology.

Leptin seems to play an important role in the generation and maintenance of immune responses. Leptin is a cytokine similar in structure to interleukin 2, an important T-cell growth factor. Energy balance and supply is increasingly being realised as an important factor in the survival and function of immune cells. Immune responses are intrinsically energy expensive and come at a cost to the responding organism. A fall in leptin concentration, as occurs in starvation, causes impaired cellular immune responses with proinflammatory and Th1 immune responses being particularly affected. Animal models of leptin deficiency show impaired cognate immune responses and are resistant to a variety of autoimmune diseases, mainly those dependent on intact T-cell immunity. The next step is to determine whether modulation of the leptin axis is therapeutically beneficial in a variety of autoimmune or infectious diseases.

Persisting Murine Cytomegalovirus Can Reactivate and Has Unique Transcriptional Activity in Ocular Tissue

Cytomegalovirus (CMV) retinitis is an important ocular complication in human immunodeficiency virus-infected individuals and the leading cause of blindness in those not undergoing highly active antiretroviral therapy. Murine CMV (MCMV) infection of mice has been shown to be a useful small-animal model for the study of CMV pathogenesis in the eye. The purpose of this study was to evaluate CMV persistence in ocular tissue and to determine the potential for reactivation. Following subretinal inoculation of immunocompetent BALB/c mice, tissues were tested for infectious virus by plaque assay and for the presence of viral DNA and RNA by PCR. The latent phase of the infection in mouse tissues was analyzed by plaque assay, PCR, and explantation cocultivation in both immunocompetent and cyclophosphamide-treated mice. The acute phase of the infection was resolved by 2 to 3 weeks postinfection, while viral DNA persisted beyond 12 months. Immediate-early 1 transcripts were detected in 100% of the ocular samples tested, and glycoprotein H transcripts were detected in 86% of the samples, but no difference in viral DNA or RNA levels between immunocompetent and immunosuppressed animals was measured. Irrespective of immune status, no in vivo reactivation was detected; however, reactivated virus was observed in 76 to 82% of the eyes following explantation onto a permissive cell layer. The transcriptional activity and relatively high frequency of explantation-induced reactivation in both immunocompetent and immunosuppressed mice suggest that control of MCMV latency in ocular tissue might involve other regulatory events that are not entirely dependent on intact specific immunity.

Effect of zinc on the tuberculin response of children exposed to adults with smear-positive tuberculosis

The tuberculin test (PPD) is used frequently in the diagnosis of tuberculosis. PPD, however, relies on an intact cell-mediated immunity and infected children often have false negative results. This study assessed whether a single oral zinc supplement modifies the PPD induration size and its association with nutritional status in Brazilian children. Ninety-eight children below 15 years of age who had been exposed to adults with smear-positive pulmonary TB in 1998 were tested by PPD in 1998 and 2000. Children were randomised in 2000 to receive a single oral dose of zinc sulphate or a placebo at the time of administering the PPD. Forty-three (44%) children were PPD-positive in 1998 and 54 (55%) in 2000. A higher proportion of children were classified as PPD-positive in 2000 in the zinc-supplemented group (57.1%) than in the placebo group (53.1%). PPD indurations were larger in children receiving zinc (mean 18.5 and 15.5 mm in the zinc and placebo groups, respectively) (p < 0.03). Mean induration sizes in 2000 were larger in zinc-supplemented children, regardless of their nutritional status. Our study demonstrates that zinc increases the PPD induration size in children irrespective of nutritional state. Zinc supplementation could work by correcting asymptomatic or marginal zinc deficiencies or as a non-specific booster of immunological mechanisms (whether or not there is a deficiency).

Complementation of a capsule deficient Cryptococcus neoformans with CAP64 restores virulence in a murine lung infection.

Cryptococcosis is a systemic infection in humans caused by the opportunistic fungal pathogen, Cryptococcus neoformans. The infection usually presents as chronic meningoencephalitis, but infects via the respiratory tract. A polysaccharide capsule is a major virulence factor, which allows the yeast to resist host defenses. However, the essential role of the capsule in allowing it to resist host defenses during the initial lung infection has not been clearly shown. A mutant acapsular C. neoformans strain 602 was complemented with the CAP64 gene to obtain an encapsulated strain, TYCC38-602. TYCC38-602 persisted in the lungs of C.B-17 mice after intratracheal inoculation and disseminated to the brain, whereas the mutant acapsular 602 and the plasmid control transformant CIP3-602 strains grew less readily in the lung and were infrequently detected in the brain. T cell-mediated immunity, developed to the encapsulated organism, was required to control growth within the lungs and had a significant impact on numbers of yeasts detected in the brain. The parent acapsular strain, but not the transformant control, also required T cells for optimal inhibition of growth within the lung, but not for maintaining control of the colony-forming units (cfu) in the brain. In summary, the cryptococcal capsule plays an important role in lung virulence and dissemination to the brain, and intact immunity is required to control lung growth of the encapsulated yeast.