The reconstitution of cell-mediated immunity in the cutaneous lesions of lepromatous leprosy by recombinant interleukin 2

Adjunctive interleukin-2 for the treatment of drug-susceptible tuberculosis: a randomized control trial in China

PURPOSE

Evaluation of the efficacy and safety of IL-2 in the treatment of drug-susceptible tuberculosis.

METHODS

First, the cases of diagnosed drug-susceptible tuberculosis were randomized into two groups-the control group that received the background regimen of isoniazid, rifampin, pyrazinamide, and ethambutol, and the experimental group that received the background regimen plus IL-2. The efficacy and safety evaluations were performed throughout the therapy process as well as 12 months after the treatment completion.

RESULTS

A total of 1151 patients underwent the randomization, among which 539 (96.2%) of the 560 in the experimental group achieved the sputum culture conversion to negative, compared to the 551 (93.2%) of the 591 in the control group, after 2 months of treatment, with significant difference observed between the groups (P = 0.025). Cavity closure after 2 months in the IL-2 (experimental) group was 60/211 (28.4%) compared to 46/248 (18.5%) in the control group, with a significant difference between the groups (P = 0.001). After treatment completion, the proportion of favorable outcomes was 559/560 (99.8%) in the experimental group and 587/591 (99.3%) in the control group, with no significant difference between the groups. Twelve months after treatment completion, relapse occurred in 15/560 (2.6%) in the IL-2 group and 19/591 (3.2%) in the control group, with no significant difference.

CONCLUSION

IL-2 may enhance culture conversion and the cavity closure rate in the early treatment phase, although the enhancement may not be significant after treatment completion.

Bi-directional relationship between pregnancy and periodontal disease

During pregnancy profound perturbations in innate and adaptive immunity impact the clinical course of a number of infectious diseases, including those affecting periodontal tissues. Conversely, it has been suggested that periodontal infections may increase the risk of adverse pregnancy outcomes. In this review, a summary of the literature associated with the bidirectional relationship between pregnancy and periodontal disease as well as the possible mechanisms behind this interaction were examined.

Immune reconstitution syndrome and exacerbation of infections after pregnancy

Pregnancy is a state of subtle immunosuppression characterized by physiologic suppression of proinflammatory host responses that are meant to promote embryonic implantation. Rapid reversal of these changes and a rebound of inflammatory responses during the postpartum period can result in quiescent or latent infection manifesting as symptomatic disease. Infections due to several microbial pathogens and noninfectious diseases with an autoimmune basis have been shown to worsen or begin during the postpartum period. Awareness that symptoms resulting from immune reconstitution can occur in any host with a rapidly changing immunologic repertoire, including women in the postpartum phase, is a critical first step in fully understanding this phenomenon. Future studies to discern the precise pathophysiologic basis of immune reconstitution, to identify pregnant women at risk, and to determine markers that may be diagnostically helpful have significant implications for optimizing treatment of these patients.

The continuing challenges of leprosy

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

Zinc and infection: a review

Dietary zinc deficiency is widespread in developing countries and is often aggravated by intercurrent acute and chronic infections. Recent studies have demonstrated that zinc supplementation can significantly reduce the morbidity and mortality of apparently well-nourished children and shorten the time to recovery from acute infectious diseases. This review summarises current knowledge of the role of zinc in childhood diarrhoea, acute respiratory infections and malaria, and its potential role in diseases associated with impaired cellular immunity, namely tuberculosis, lepromatous leprosy and leishmaniasis, and explores avenues for future research.

Genetic dissection of immunity in leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae that affects an estimated 700,000 new individuals each year. A strong contribution of host genetics to susceptibility to leprosy has long been suggested to account for the considerable variability observed between individuals exposed to M. leprae. As there is no relevant animal model for human leprosy, forward genetics is the main strategy used to identify the genes and, consequently, the immunological pathways involved in protective immunity to M. leprae. With respect to genome-wide screens, a major breakthrough has been reported this year; variants in the regulatory region shared by PARK2 and PACRG have been identified as being common risk factors for leprosy.

An in vitro model for the lepromatous leprosy granuloma: fate of Mycobacterium leprae from target macrophages after interaction with normal and activated effector macrophages

The lepromatous leprosy granuloma is a dynamic entity requiring a steady influx of macrophages (Mphi) for its maintenance. We have developed an in vitro model to study the fate of Mycobacterium leprae in a LL lesion, with and without immunotherapeutic intervention. Target cells, consisting of granuloma Mphi harvested from the footpads of M. leprae-infected athymic nu/nu mice, were cocultured with normal or IFN-gamma-activated (ACT) effector Mphi. The bacilli were recovered and assessed for viability by radiorespirometry. M. leprae recovered from target Mphi possessed high metabolic activity, indicating a viable state in this uncultivable organism. M. leprae recovered from target Mphi incubated with normal effector Mphi exhibited significantly higher metabolism. In contrast, bacilli recovered from target Mphi cocultured with ACT effector Mphi displayed a markedly decreased metabolic activity. Inhibition by ACT Mphi required an E:T ratio of at least 5:1, a coculture incubation period of 3-5 days, and the production of reactive nitrogen intermediates, but not reactive oxygen intermediates. Neither IFN-gamma nor TNF-alpha were required during the cocultivation period. However, cell-to-cell contact between the target and effector Mphi was necessary for augmentation of M. leprae metabolism by normal effector Mphi as well as for inhibition of M. leprae by ACT effector Mphi. Conventional fluorescence microscopy and confocal fluorescence microscopy revealed that the bacilli from the target Mphi were acquired by the effector Mphi. Thus, the state of Mphi infiltrating the granuloma may markedly affect the viability of M. leprae residing in Mphi in the lepromatous lesion.

Molecular mechanisms of MHC linked susceptibility in leprosy: towards the development of synthetic vaccines

Tuberculoid (TT) and lepromatous leprosy (LL) develop in the human host depending on his ability to trigger a specific cellular immune response(CIR). Different genes have been demonstrated in susceptibility/protection and may explain the forms of leprosy. The major histocompatibility complex (MHC) play an important role. The aim of the study was to explore the contribution of human leukocyte antigen (HLA) DRB1, DQA1, DQB1 and DQ promoter genes in LL Mexican patients. Six families (26 LL, three TT patients and 27 controls) were analyzed; 114 unrelated patients were compared with 204 controls. Class I typing was done by the standard microlymphocytotoxicity and class II typing using PCR-SSOP. Haplotype segregation correlated with specific CIR in vivo and in vitro using lepromin. Haplotype sharing was significantly deviated in the affected sibs (p=0.01). Six healthy sibs were non-responders to lepromin and four of them were DQ1 homozgotes. DQ1 was significantly associated with LL and with non-responders. We set up macrophage activation experiments after infecting these cells with 5x10(6) bacilli to demonstrate if elimination occurred in the context or DQ1. When DQ1 was present on macrophages and on T cells, bacteria were poorly eliminated from the cell (32%) while when absent, 76% of the individuals were able to eliminate the bacilli (p=0.03). DRB1*1501 DQA1*0102-DQB1*0602 (DQ1 subtype) was significantly increased in the patients, indicating its participation in susceptibility. QBP 5.11/5.12 promoter present in the mentioned haplotype, and QAP 1.4, linked to DRB1*1301/02 haplotypes were also associated. Two mechanisms are suggested: the promoter polymorphisms may influence allele expression and thus the amount of peptides presented to the T-cell receptor, leading to a deficient CIR: HLA restriction is important for vaccine design; the way peptides anchor the DRB1*1501 groove may be relevant to the activation of TH1 cells, which contribute to an efficient presentation of peptides inducing a protective T-cell response.

Randomized trial of adjunctive interleukin-2 in adults with pulmonary tuberculosis

Interleukin (IL)-2 has a central role in regulating T cell responses to Mycobacterium tuberculosis. Adjunctive immunotherapy with recombinant human IL-2 was studied in a randomized, placebo-controlled, double-blinded trial in 110 human immunodeficiency virus-seronegative adults in whom smear-positive, drug-susceptible pulmonary tuberculosis was newly diagnosed. Patients were randomly assigned to receive twice-daily injections of 225, 000 IU of IL-2 or placebo for the first 30 days of treatment in addition to standard chemotherapy. Subjects were followed for 1 year. The primary endpoint was the proportion of patients with sputum culture conversion after 1 and 2 months of treatment. After 1 month, the proportion of patients for whom sputum culture converted to negative was 17% for the IL-2 group compared with 30% in the control group (p = 0.14; chi2). After 2 months, 77% in the IL-2 group were culture negative compared with 85% of those receiving placebo (p = 0.29, chi2). Results were similar when patients with isoniazid monoresistance were included in the analysis. There were no differences in weight gain and no improvement in fever, cough, and chest pain between groups. One patient in each arm relapsed. IL-2 did not enhance bacillary clearance or improvement in symptoms in human immunodeficiency virus-seronegative adults with drug-susceptible tuberculosis.

Interleukin-2 and cancer: critical analysis of results, problems and expectations

The cancer process in a combination of two kinds of events: a multistep cellular genetic defects giving cells independent growth and great adaptation capability, a multistep interactions profiles with what is called the stromal reaction from the original in situ tumor to the invasive metastatic and angiogenic tumor. The immune system plays an important role in the control of the cancer process but always must be seen as a part integrated in the stromal reaction. In order to boost the immune system capability to treat a cancer we must never forget these cellular and tissular dimensions. Interleukins, growth factors and monoclonal antibodies are new agents are able to bring immunotherapy of cancer to reality. Interleukin 2 did not match our dreams of the ideal factor which can stimulate the defective immune system and bring the cancer evolution to an end. The little but real remissions obtained with the IL-2 high dose protocols still sustains our trust of the immune system as a critical barrier to cancer evolution but the numerous side effects reminds us that cytokines are not to be used as antibiotics and hormones. IL-2 is a regulator of the immune system at the microenvironment level, therefore flooding the blood circulation with high IL-2 doses is not appropriate. We have also to understand that IL-2 can interact directly with cancer cells and also with stromal cells (endothelial and fibroblastic cells), the outcome of IL-2 immunotherapy is not restricted to the interactions with immune cells.

Ontogeny and expansion of human natural killer cells: clinical implications

Our knowledge of NK cells and their critical role in the innate immune system has increased enormously since their discovery several decades ago. However, it is only within the last 10 years that rational cytokine therapies, such as those utilizing low doses of IL-2, have been successful in expanding NK cells in patients with cancer and/or immunodeficiency. Such experiences in vivo have highlighted the importance of basing immunotherapeutic strategies on the known cellular and molecular properties of the targeted cell population. Recent advances in our understanding of the physiologic factors and events that orchestrate NK cell ontogeny, including IL-15 and receptor tyrosine kinase ligands to c-kit and flt3, provide novel therapeutic possibilities for cytokine therapy. This review summarizes our current understanding of human NK cell ontogeny, and links this knowledge to ongoing and future clinical strategies for the endogenous expansion of NK cells in patients with cancer and/or immunodeficiency.

Mycobacterium leprae-specific, HLA class II-restricted killing of human Schwann cells by CD4+ Th1 cells: a novel immunopathogenic mechanism of nerve damage in leprosy

Peripheral nerve damage is a major complication of reversal (or type-1) reactions in leprosy. The pathogenesis of nerve damage remains largely unresolved, but detailed in situ analyses suggest that type-1 T cells play an important role. Mycobacterium leprae is known to have a remarkable tropism for Schwann cells of the peripheral nerve. Reversal reactions in leprosy are often accompanied by severe and irreversible nerve destruction and are associated with increased cellular immune reactivity against M. leprae. Thus, a likely immunopathogenic mechanism of Schwann cell and nerve damage in leprosy is that infected Schwann cells process and present Ags of M. leprae to Ag-specific, inflammatory type-1 T cells and that these T cells subsequently damage and lyse infected Schwann cells. Thus far it has been difficult to study this directly because of the inability to grow large numbers of human Schwann cells. We now have established long-term human Schwann cell cultures from sural nerves and show that human Schwann cells express MHC class I and II, ICAM-1, and CD80 surface molecules involved in Ag presentation. Human Schwann cells process and present M. leprae, as well as recombinant proteins and peptides to MHC class II-restricted CD4(+) T cells, and are efficiently killed by these activated T cells. These findings elucidate a novel mechanism that is likely involved in the immunopathogenesis of nerve damage in leprosy.

Treatment of infections in the patient with Mendelian susceptibility to mycobacterial infection

Cytokines are increasingly used for the therapy of infections in patient populations with special defects in immunity (chemotherapy, bone marrow transplantation, chronic granulomatous disease). The recognition of multiple defects in the systems of the interferon-gamma (IFN-gamma) receptor, interleukin-12 (IL-12) receptor and IL-12 p40 emphasizes the critical roles that cytokines play in preventing and clearing infection. The cases of patients with partially responsive IFN-gamma receptors (autosomal dominant and partial defects) are ideal candidates for successful cytokine prophylaxis and therapy. Better understanding of the critical elements of the cytokine pathways may show us ways to circumvent these defects with complementary cytokine cascades.

The Tumorigenicity of IL-2 Gene-Transfected Murine M-3D Melanoma Cells Is Determined by the Magnitude and Quality of the Host Defense Reaction: NK Cells Play a Major Role

Transfection of a variety of tumor lines with the IL-2 gene strongly reduces their tumorigenic potential when applied to either euthymic or athymic animals. To elucidate the mechanisms underlying this phenomenon, we inoculated IL-2-transfected M-3D melanoma (M-3D-IL-2) cells into DBA/2 mice immunosuppressed by γ-irradiation. Animals thus treated developed pigmented tumors, suggesting that IL-2 transfection of melanoma cells, instead of altering their neoplastic growth properties, renders them capable of evoking a tumoricidal host response. To define the critical effector cell, we injected M-3D-IL-2 and, for control purposes, nontransfected M-3D cells into DBA/2 recipients and analyzed the injection site. We found that 1) IL-2-expressing M-3D cells induce a much stronger inflammatory reaction than wild-type cells, 2) in both instances the infiltrate consists mainly of macrophages (40–60%) and granulocytes (30–40%), and 3) only the infiltrate of M-3D-IL-2 cell deposits contains a minor fraction of NK cells (∼1–2%). When we reconstituted sublethally irradiated animals with various leukocyte subsets, we found that unfractionated as well as macrophage-depleted peritoneal lavage cells but not NK cell-depleted peritoneal lavage cells were able to suppress the growth of IL-2-expressing M-3D cells. In vivo leukocyte depletion experiments showed that the NK cell-depleting asialo-GM1 antiserum, but not anti-macrophage and/or anti-granulocyte reagents, restored the tumorigenicity of M-3D-IL-2 cells. Our results indicate that the inflammatory tissue response evoked by IL-2-transfected cancer cells includes the attraction and/or activation of NK cells and that, in the experimental system used, these cells are critically needed for successfully controlling cancer growth in vivo.

Multibacillary leprosy: lesions with macrophages positive for S100 protein and dendritic cells positive for Factor 13a

In the defense against Mycobacterium leprae, macrophages play an essential part in the mechanism of bacterial lysis but require the presence of cytokines such as interleukin 2 and gamma interferon from lymphocytes in order to effectively kill the organisms in any number. While there have been many studies of the lymphocytes in lesions of leprosy, less attention has been given to the immunohistochemical characterization of the macrophage populations. In this study, the cutaneous lesions of 69 patients with leprosy (42 lepromatous, 5 mid-borderline, and 22 tuberculoid) were evaluated by immunohistochemistry for the expression of S100 protein, CD1a, CD68, muramidase, HLA-DR, and Factor 13a. The macrophages from lesions of polar, subpolar, and borderline lepromatous leprosy patients expressed S100 protein intensely and constantly. In contrast, the lesions of polar and subpolar tuberculoid leprosy had very few cells that were immunoreactive for S100 protein ('S100+') in the granulomas in the dermis. The macrophages in all lesions were reactive for CD68 and muramidase. In paraffin sections, macrophages of lepromatous lesions failed to stain for HLA-DR, whereas in tuberculoid lesions, they were strongly positive for HLA-DR. Three patients with histoid leprosy (relapse lesions) had lesions that were strongly positive for Factor 13a and were negative for S100 protein ('S100-'). Given the possible chemotactic and migration inhibition effects of the calcium-binding proteins of the S100 family, these data suggest a possibly important role for S100 protein in the accumulation of macrophages in lepromatous leprosy, and also reveal infection of Factor 13a + dermal dendritic cells in histoid leprosy.

Expression and cytokine secretion in the states of immune reactivation in leprosy

Leprosy is a chronic inflammatory disease caused by Mycobacterium leprae. The human response to this pathogen exhibits intriguing aspects which are up to now not well understood. The present study discusses the probable mechanisms involved in T cell-specific unresponsiveness observed in lepromatous patients. Analysis of the cytokine profile either in blood leukocytes or in skin specimens taken from leprosy lesions indicates that some parameters of Th1 immune response are present in lepromatous patients under reactional states.

The immunobiology of interferon-gamma inducible protein 10 kD (IP-10): a novel, pleiotropic member of the C-X-C chemokine superfamily

Interferon-gamma inducible protein 10 kD (IP-10) is a highly inducible, primary response gene that belongs to the C-X-C chemokine superfamily. Despite the original cloning of IP-10 in 1985, its biological functions are still unclear although accumulating reports indicate that it is a pleiotropic molecule capable of eliciting potent biological effects, including stimulation of monocytes, natural killer and T-cell migration, regulation of T-cell and bone marrow progenitor maturation, modulation of adhesion molecule expression as well as inhibition of angiogenesis. More interest is now likely to be focused on IP-10 due to the recent cloning of an IP-10 receptor. This paper aims to highlight our current knowledge of IP-10 and its homologues as well as defining its likely involvement in regulating fibroproliferation following inflammatory lung injury.

Antibody- and cell-mediated immune responses of Actinobacillus pleuropneumoniae-infected and bacterin-vaccinated pigs

Current porcine pleuropneumonia bacterins afford only partial protection by decreasing mortality but not morbidity. In order to better understand the type(s) of immune response associated with protection, antibody- and cell-mediated immune responses (CMIR) were compared for piglets before and after administration of a commercial bacterin, which confers partial protection, or a low-dose (10(5) CFU/ml) aerosol challenge with Actinobacillus pleuropneumoniae CM5 (LD), which induces complete protection. Control groups received phosphate-buffered saline or adjuvant. Serum antibody response, antibody avidity, delayed-type hypersensitivity (DTH), and lymphocyte blastogenic responses were measured and compared among treatment groups to the lipopolysaccharide (LPS), capsular polysaccharide (CPS), hemolysin (HLY), and outer membrane proteins (OMP) of A. pleuropneumoniae. Peripheral blood lymphocytes and sera were collected prior to and following primary and secondary immunization-infection and high-dose A. pleuropneumoniae CM5 (10(7) CFU/ml) aerosol challenge. Serum antibody and DTH, particularly that to HLY, differed significantly between treatment groups, and increases were associated with protection. LD-infected piglets had higher antibody responses (P < or = 0.01) and antibody avidity (P < or = 0.10) than bacterin-vaccinated and control groups. Anti-HLY antibodies were consistently associated with protection, whereas anti-LPS and anti-CPS antibodies were not. LD-infected animals had higher DTH responses, particularly to HLY, than bacterin-vaccinated pigs (P < or = 0.03). The LD-infected group maintained consistent blastogenic responses to HLY, LPS, CPS, and OMP over the course of infection, unlike the bacterin-vaccinated and control animals. These data suggest that the immune responses induced by a commercial bacterin are very different from those induced by LD aerosol infection and that current bacterins may be modified, for instance, by addition of HLY, so as to stimulate responses which better reflect those induced by LD infection.

Clonal T cell expansion induced by interleukin 2 therapy in blood and tumors

In a phase I clinical trial on the effects of preoperative adjuvant IL-2 therapy given to patients undergoing hepatic resection of colorectal adenocarcinoma metastases, we monitored the putative induction of T cell clonal expansion in both tissues and blood. The presence of T cell clonotypes was analyzed with a PCR-based method that determines V-D-J junction size patterns in T cell receptor (TCR) V beta subfamilies in samples before and after a 5-d IL-2 infusion. This high resolution method analyzing CDR3 sizes of TCR transcripts was used in conjunction with FACS analysis of the corresponding T cell subpopulations with TCR V beta-specific mAb. At time of surgery (day 8 after starting IL-2), we found in the three patients analyzed with V beta-C beta primers multiple dominant T cell clonotypes in the tumor and peritumoral tissues which had probably expanded as a result of therapy. In three control patients not treated with IL-2, multiple oligoclonal patterns were not observed with this set of primers. In the fourth control patient a unique V beta 21-C beta CDR3 pattern which corresponds to two dominant clonotypes was found in the tumor. The same dominant clonotypes identified in the tumor after IL-2 were also detectable in the blood and comparison of the profiles obtained before and after IL-2 therapy indicates that they were induced by IL-2. The relative expansion of the corresponding T cell subpopulations was maintained for varying periods of time after surgery (4-7 d and almost 2 yr in one case). Together, these results indicate that IL-2 induces marked expansion of several T cell clones. Systemic IL-2 administration may represent, either alone or as a vaccine adjuvant, an appropriate way of boosting antigen-specific immune responses.

Low-dose IL-2 treatment: activation of discrete T- and NK-cell sub-populations in vivo

The activation of T- and NK-cell sub-populations in vivo was evaluated in a phase-I study (18 patients) with a 3-month course of low-dose s.c. IL-2, 1, 3 and 6 x 10(6) IU/day once daily, 6 days a week. At the higher doses, we observed early on (day 15) an increase in CD3+ CD56-, CD3- CD56+ and CD56+ DR+ cell counts, as well as an increase in circulating sIL-2R and non-MHC-restricted cytotoxicity against K562 and Daudi cells. In contrast, at the lowest dose, T- and NK-cell counts were not appreciably altered, while a substantial increase in NK cytotoxic activity was still observed. In addition, thyroid dysfunction resembling that described in auto-immune thyroiditis, was documented in 6 out of the 14 patients studied. Using a high-resolution method analyzing CDR3 sizes of TCR beta transcripts, we observed the appearance of dominant T-cell clonotypes in 1 patient out of 2 analyzed, corresponding to the clonal expansion of T cells primed in vivo. Overall, these results show that long courses of low-dose s.c. IL-2 treatment lead to the activation of discrete T- and NK-cell sub-populations.

Itch and inflammation induced by intradermally injected interleukin-2 in atopic dermatitis patients and healthy subjects

To explore the pruritogenic and inflammatory effects of cytokines, a single dose of 20 micrograms recombinant human interleukin-2 was injected intradermally into eight patients with atopic dermatitis and eight healthy controls. The study was double-blind and randomized with glucose as a negative control. The effects were evaluated by recording local itch and erythema over 72 h and by examining skin biopsies taken at 24 h and 72 h. In patients and controls, interleukin-2 provoked a low-intensity local itch with maximal intensity between 6 h and 48 h and erythema with maximal extension between 12 h and 72 h. In the atopic dermatitis patients, these reactions tended to appear earlier and were less pronounced than in the healthy controls. Interleukin-2 induced dermal mononuclear cell infiltrates consisting mainly of CD3+ cells. A majority of the T cells were CD4+. The number of dermal CD25+, HLA-DR+ and ICAM-1+ cells was also increased at the interleukin-2 induced spongiosis and exocytosis as well as HLA-DR+ and ICAM-1+ keratinocytes. The microscopic findings tended to be more prominent at 72 h than at 24 h in both groups, but with a somewhat slower onset in the atopic dermatitis patients. In conclusion, a single intradermal injection of interleukin-2 induced local itch, erythema, dermal T-cell infiltrates, spongiosis, exocytosis and activation of keratinocytes both in atopic dermatitis patients and in healthy controls.

Recombinant cytokines for controlling mycobacterial infections

Knowing how mycobacteria exploit host cytokines to survive and which cytokines have important roles in host defense against mycobacteria should allow the use of these molecules in the treatment of mycobacterial infections. Both interleukin 2 and interferon gamma have been used to treat patients with leprosy, and granulocyte-macrophage colony-stimulating factor is presently being administered to AIDS patients infected with Mycobacterium avium.

Phase 1 trial of immunological adjuvant QS-21 with a GM2 ganglioside-keyhole limpet haemocyanin conjugate vaccine in patients with malignant melanoma

Increasing doses of saponin fraction QS-21 were administered as immunological adjuvant in a Phase 1 trial with a constant dose of the melanoma ganglioside GM2 covalently attached to keyhole limpet haemocyanin (KLH). Twenty-eight patients with AJCC Stage III or IV melanoma who were free from disease after surgery were treated with six vaccinations administered subcutaneously over a 5-month period. Local and systemic reactions were QS-21 dose-related. Doses of < or = 100 micrograms induced mild local tenderness and inflammation at vaccination sites lasting 2-4 days and occasional brief low-grade fever and malaise, but no significant incapacitation. The 200 micrograms dose induced low-grade fever and malaise after 30% of vaccinations and local reactions as large as 20 cm in diameter were seen in all patients, resulting in discomfort with usage of the injected extremity for 5-10 days. The titres of IgM and IgG antibodies against GM2, and IgG antibodies against KLH, were highest at the 100 and 200 micrograms QS-21 doses. No antibodies against QS-21 were detected. This trial identifies the 100 micrograms dose of QS-21 as the optimal well tolerated dose for induction of antibodies against both the melanoma ganglioside/GM2 and the protein KLH in melanoma patients.

Effects of human recombinant interleukin-2 on resistance, and on the humoral and cellular response of rabbits infested with adult Ixodes ricinus ticks

Rabbits were treated with subcutaneous injections of ten doses of 5 x 10(3) units of human recombinant interleukin-2 (IL-2) during a first infestation with five adult pairs Ixodes ricinus per rabbit, while untreated controls were infested by either five (direct control) or 25 pairs (resistant control) per rabbit. During the second infestation with 25 pairs per rabbit in each group, rabbits treated with IL-2 became more resistant than the rabbits in the two untreated control groups. Stronger resistance was manifested by lower engorgement and egg laying weights, and by smaller numbers of normally fed or ovipositioning ticks. IL-2 treatment had no significant effects on the rabbit anti-tick antibody production and the lymphocyte proliferation to a salivary gland extract (SGE). By contrast, the highest cutaneous responses to SGE were observed in the IL-2 treated group. IL-2 may increase rabbit cell-mediated immunity, and stimulate an increase in the production of memory cells during the induction phase of the immune response (first infestation), allowing the development of a strong resistance in lightly infested rabbits.

Cutaneous-malignancy and leprosy. Report of a patient with Mycobacterium leprae and basal cell carcinoma concurrently present in the same lesion

BACKGROUND

Leprosy is a chronic systemic infection caused by the bacillus Mycobacterium leprae. Cutaneous neoplasms have been observed in patients with leprosy. Also, albeit less commonly, M. leprae have been documented in the lesions of skin cancer.

OBJECTIVE

To describe a 62-year-old man with chronic sun exposure and exposure to armadillos who subsequently developed lepromatous leprosy, to discuss the cutaneous malignancies that have occurred in patients with leprosy, and to review the literature concerning the concurrent presence of an infectious pathogen and a cutaneous neoplasm in the same lesion.

METHODS

Our patient's basal cell carcinomas were excised, his abdominal plaques were biopsied, and his leprosy infection was treated with dapsone and rifampin. The types of cutaneous malignancies in leprosy patients and infectious pathogens concurrently found in lesions of skin tumors were summarized after evaluating previously published reports.

RESULTS

Skin biopsies from our patient demonstrated M. leprae bacilli not only in his abdominal plaques, but also in all of his basal cell carcinoma lesions. Fungal, mycobacterial, and viral pathogens have concurrently been observed in skin lesions of basal cell carcinomas, Kaposi's sarcoma, melanoma, mycosis fungoides, and squamous cell carcinoma.

CONCLUSION

Patients with leprosy can develop skin cancers and the histologic interpretation of those skin cancers can show evidence of leprosy. It is uncertain to what degree the decreased cell-mediated immunity in patients with lepromatous leprosy either enhances their susceptibility to and/or influences the course of their cutaneous neoplasms; also, in these patients, the coexistence of M. leprae organisms and cutaneous malignancy in the same lesion is likely to be secondary to the high bacillary load that is present.

Th1-Th2 paradigm: insights from leprosy

The mechanism by which T cells and cytokines regulate immune processes in skin can be investigated by studying patients with leprosy. The disease, caused by the obligate intracellular bacterium Mycobacterium leprae, forms a spectrum. At one pole, patients with tuberculoid leprosy are able to restrict the growth of the pathogen and their skin lesions are characterized by a predominance of CD4+ T cells and type 1 cytokines including interleukin 2 and interferon gamma. At the opposite pole, patients with lepromatous leprosy are unable to contain the infection and their skin lesions are characterized by a predominance of CD8+ T cells and type 2 cytokines including interleukins 4 and 10. A key determinant of the T-cell cytokine response may be interleukin 12, which selectively favors expansion of CD4+ T cells producing interferon gamma. By understanding the factors that regulate T-cell and cytokine responses in leprosy, it should be possible to devise specific immunologic interventions in diseases of skin.

Constitutive expression of interferon gamma-inducible protein 10 in lymphoid organs and inducible expression in T cells and thymocytes

Interferon gamma-inducible protein 10 (IP-10), a member of a family of small proinflammatory chemotactic polypeptides, is expressed in interferon gamma-stimulated keratinocytes, macrophages, fibroblasts, and endothelial cells. Here we report that IP-10 is also expressed by activated but not resting T hybridoma cells, normal T cells, and thymocytes. Although resting lymphocytes did not synthesize IP-10, surprisingly high levels of IP-10 transcripts were found in lymphoid organs (spleen, thymus, and lymph nodes). Thymic and splenic stromal cells were found to express constitutively high levels of both IP-10 mRNA and protein, accounting for the high level of spontaneous expression in lymphoid tissue. Therefore, in addition to its role as a proinflammatory cytokine, IP-10 may participate in T cell effector function and perhaps T cell development.

Zanvil Alexander Cohn 1926-1993

Zanvil Alexander Cohn, an editor of this Journal since 1973, died suddenly on June 28, 1993. Cohn is best known as the father of the current era of macrophage biology. Many of his scientific accomplishments are recounted here, beginning with seminal studies on the granules of phagocytes that were performed with his close colleague and former editor of this Journal, James Hirsch. Cohn and Hirsch identified the granules as lysosomes that discharged their contents of digestive enzymes into vacuoles containing phagocytosed microbes. These findings were part of the formative era of cell biology and initiated the modern study of endocytosis and cell-mediated resistance to infection. Cohn further explored the endocytic apparatus in pioneering studies of the mouse peritoneal macrophage in culture. He described vesicular inputs from the cell surface and Golgi apparatus and documented the thoroughness of substrate digestion within lysosomal vacuoles that would only permit the egress of monosaccharides and amino acids. These discoveries created a vigorous environment for graduate students, postdoctoral fellows, and junior and visiting faculty. Some of the major findings that emerged from Cohn's collaborations included the radioiodination of the plasma membrane for studies of composition and turnover; membrane recycling during endocytosis; the origin of the mononuclear phagocyte system in situ; the discovery of the dendritic cell system of antigen-presenting cells; the macrophage as a secretory cell, including the release of proteases and large amounts of prostaglandins and leukotrienes; several defined parameters of macrophage activation, especially the ability of T cell-derived lymphokines to enhance killing of tumor cells and intracellular protozoa; the granule discharge mechanism whereby cytotoxic lymphocytes release the pore-forming protein perforin; the signaling of macrophages via myristoylated substrates of protein kinase C; and a tissue culture model in which monocytes emigrate across tight endothelial junctions. In 1983, Cohn turned to a long-standing goal of exploring host resistance directly in humans. He studied leprosy, focusing on the disease site, the parasitized macrophages of the skin. He injected recombinant lymphokines into the skin and found that these molecules elicited several cell-mediated responses. Seeing this potential to enhance host defense in patients, Cohn was extending his clinical studies to AIDS and tuberculosis. Zanvil Cohn was a consummate physician-scientist who nurtured the relationship between cell biology and infectious disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Lymphocyte infiltration of the skin in transgenic mice carrying the human interleukin-2 gene

Inflammatory lesions of the skin such as erythema, depigmentation and hair loss were observed in C57/BL6(B6) transgenic mice that carried an intact human genomic interleukin-2 gene (gIL-2 transgenic mice). Accumulation of T lymphocytes in the perivascular and periadnexal areas of the dermis was the first change, followed by dermal papillary oedema, which occurred before the development of macroscopic skin lesions. In 3- or 4-week-old transgenic mice with slight erythema and depigmentation of the skin, there was an increase in the number of perivascular lymphocytes accompanied by the diffuse infiltration of neutrophils and monocytes in the damaged skin. These morphological skin changes were not observed in non-transgenic mice, which were bred together with transgenic litter mates. These findings suggest that lymphocyte infiltration of the perivascular space of the skin is a primary event of exogenously introduced human interleukin-2 gene, resulting in secondary cutaneous changes in gIL-2 transgenic mice.

Pilot study of natural human interleukin-2 in patients with chronic hepatitis B. Immunomodulatory and antiviral effects

Ten patients with chronic hepatitis B received increasing doses of nIL-2 (30,000 U, 100,000 U, 300,000 U, 1.0 million U) subcutaneously in a phase I trial. Each dose was applied once per week over 3 weeks. Serum samples were taken before and 2, 12, 24, 48 and 72 h after the first application of each dose level. Serum concentrations of interleukin-1 (IL-1), IL-2, IL-6, interferon-alfa (IFN-alpha), IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and GM-CSF as well as the cytokine-dependent serum components neopterin, beta-2-microglobulin (B2M), C-reactive protein (CPR), soluble IL-2-receptor (sIL-2R) and 2'-5'-oligoadenylate synthetase (2-5 OA) were assayed using ELISAs and RIAs. None of the samples tested contained measurable cytokine levels other than IL-2. A low and non-toxic dose of 300,000 U nIL-2 was already biologically active with induction of neopterin, B2M and sIL-2R. Dose-dependent changes peaked 24-48 h after application. The same patients were then enrolled in a phase II trial. Treatment in five of the patients was continued twice per week for 3 months with a biologically active dose of 300,000 U nIL-2 subcutaneously. Two of these patients as well as another five patients from the original group were treated with 1.0 million U nIL-2 subcutaneously, twice weekly for 3 months. Neither a biologically active but non-toxic dose of 300,000 U nIL-2, nor a toxic dose of 1.0 million U resulted in permanent clearance of hepatitis B early antigen (HBeAg).(ABSTRACT TRUNCATED AT 250 WORDS)

Recognition and destruction of Bacillus Calmette-Guerin-infected human monocytes

We have established a long-term culture system to study macrophages chronically infected with mycobacteria. Monocytes are infected with Bacillus Calmette-Guerin (BCG) and support exponential intracellular replication without profound perturbation of normal host cell function. We have used this system to investigate lymphokine-activated killer (LAK)-mediated cytolysis. We have found that interleukin 2 stimulation of peripheral blood lymphocytes generates a cytotoxic activity against human monocytes. A CD56- subpopulation of LAK cells specifically recognizes and lyses BCG-infected cells. Lysis of the host cell has no effect on parasite viability and results in the liberation of bacteria capable of infecting more cells.

Prolonged immunostimulatory effect of low-dose polyethylene glycol interleukin 2 in patients with human immunodeficiency virus type 1 infection

13 patients with human immunodeficiency virus type 1 infection class II-IV, but without opportunistic infection or neoplasm, received 6 micrograms (3.6 x 10(4) IU) of polyethylene glycol recombinant human interleukin 2 (PEG IL-2) intradermally twice a week for 4 mo were then followed for an additional 6 mo. Clinical, immunological, and viral parameters were monitored in the patients, all of whom were taking zidovudine. The cutaneous administration of PEG IL-2 resulted in an indurated zone resembling a delayed-type hypersensitivity response of 26 +/- 1 mm diameter (676 mm2) at 72-96 h after injection throughout the 4 mo of administration. This dose, which was appreciably lower than in most previous trials, was not associated with local or systemic toxicity. No increase in the viral burden of circulating leukocytes or plasma occurred. A number of immunological functions were stimulated by this course of therapy. All patients demonstrated high levels of lymphokine-activated killer cell activity by cells freshly removed from the circulation and in the absence of in vitro exposure to IL-2. Natural killer cell activity was also enhanced. Limiting dilution analysis revealed an increase in the frequency of IL-2-responsive cells from abnormally low to levels above normal during the course of injections. In a subgroup of four patients with > or = 400 CD4+ T cells/microliter at entry, there was a trend to sustained increases in CD4+ T cell numbers. However, this increase did not reach statistical significance. This subset of patients also exhibited higher proliferative responses to phytohemagglutinin as mitogen. Several of these effects persisted for 3-6 mo after cessation of therapy. In conclusion, low-dose IL-2 regimens lead to sustained immune enhancement in the absence of toxicity. We suggest pursuit of this approach for further clinical trials both as prophylaxis and therapy.

Inhibition of growth of Mycobacterium avium in murine and human mononuclear phagocytes by migration inhibitory factor

Infections caused by Mycobacterium avium, the most common form of diseminated bacterial disease in AIDS patients, are difficult to treat because of their resistance to many antimycobacterial drugs. The results of the present study show that recombinant migration inhibitory factor, a 12-kDa molecule recently isolated by COS-1 cell expression screening of cDNA from a human T-cell hybridoma, has potent inhibitory activity on the growth of a panel of clinical isolates of M. avium within both bone-marrow-derived murine macrophages and cultured human blood monocytes. These cells cultured in recombinant migration inhibitory factor exhibit various signs of activation, including cell division, morphological changes such as evidence of substantial phagolysosomal fusion, and enhanced secretion of tumor necrosis factor.

Immunotherapy of airborne tuberculosis in mice via the lung-specific delivery of cytokines

The immunotherapeutic potential of interleukin-2 (IL-2), tumour necrosis factor alpha (TNFα) and interferon gamma (IFN-γ) administered by aerosol was examined on mice infected with Mycobacterium tuberculosis by the aerogenic route. Infection of balb/c mice with 10(4) colony forming units (cfu) of M tuberculosis led to death of all mice at day 35 post infection after progressive microbial growth in the lungs. Aerosolization of IL-2 (100 μg per mouse) did not promote an increase in resistance to tuberculosis, as seen by growth of M tuberculosis in the lungs. Administration of IFN-γ or TNFα (100 μg) by the aerosol route led to a significant reduction in microbial growth in the lungs and a 100% survival of infected mice at day 60. Similarly, aerosolization of TNFα and IFN-γ combined led to a very high degree of tuberculostatic activity in the lungs of infected animals, but not superior to that seen with either cytokine alone. Administration of similar amounts of cytokines by repeated intraperitoneal infusions led to a very marginal improvement in mouse resistance. These results suggest that localized cytokine administration may be beneficial in the treatment of lung diseases.

Selective modulation of human natural killer cells in vivo after prolonged infusion of low dose recombinant interleukin 2

The immunologic consequences of prolonged infusions of rIL-2 in doses that produce physiologic serum concentrations of this cytokine were investigated. rIL-2 in doses of 0.5-6.0 x 10(6) U/m2 per d (3.3-40 micrograms/m2 per d) was administered by continuous intravenous infusion for 90 consecutive days to patients with advanced cancer. IL-2 concentrations (25 +/- 25 and 77 +/- 64 pM, respectively) that selectively saturate high-affinity IL-2 receptors (IL-2R) were achieved in the serum of patients receiving rIL-2 infusions of 10 micrograms/m2 per d and 30 micrograms/m2 per d. A gradual, progressive expansion of natural killer (NK) cells was seen in the peripheral blood of these patients with no evidence of a plateau effect during the 3 mo of therapy. A preferential expansion of CD56bright NK cells was consistently evident. NK cytotoxicity against tumor targets was only slightly enhanced at these dose levels. However, brief incubation of these expanded NK cells with IL-2 in vitro induced potent lysis of NK-sensitive, NK-resistant, and antibody-coated targets. Infusions of rIL-2 at 40 micrograms/m2 per d produced serum IL-2 levels (345 +/- 381 pM) sufficient to engage intermediate affinity IL-2R p75, which is constitutively expressed by human NK cells. This did not result in greater NK cell expansion compared to the lower dose levels, but did produce in vivo activation of NK cytotoxicity, as evidenced by lysis of NK-resistant targets. There was no consistent change in the numbers of CD56- CD3+ T cells, CD56+ CD3+ MHC-unrestricted T cells, or B cells during infusions of rIL-2 at any of the dosages used. This study demonstrates that prolonged infusions of rIL-2 in doses that saturate only high affinity IL-2R can selectively expand human NK cells for an extended period of time with only minimal toxicity. Further activation of NK cytolytic activity can also be achieved in vivo, but it requires concentrations of IL-2 that bind intermediate affinity IL-2R p75. Clinical trials are underway attempting to exploit the differing effects of various concentrations of IL-2 on human NK cells in vivo.

Generation of cytolytic T cells in individuals infected by Mycobacterium tuberculosis and vaccinated with BCG

BACKGROUND

Macrophage activation by cytokines provides only a partial explanation of antimycobacterial immunity in man. Because cytolytic T lymphocytes have been shown to contribute to immunity in animal models of intracellular infection, the generation of mycobacterial antigen specific cytotoxic T cells was examined in the peripheral blood of patients with tuberculosis.

METHODS

Subjects comprised 36 patients with active tuberculosis (18 newly diagnosed) and 32 healthy volunteers, of whom 25 had had BCG vaccination and seven were Mantoux negative. The ability of purified protein derivative (PPD) stimulated peripheral blood lymphocytes to lyse autologous, mycobacterial antigen bearing macrophages was examined by using a chromium 51 release assay.

RESULTS

PPD stimulated lymphocytes from normal, Mantoux positive, BCG vaccinated subjects produced high levels of PPD specific cytolysis, whereas lymphocytes from unvaccinated, uninfected subjects caused little or no cytolysis. The generation of cytolytic T lymphocytes by patients with tuberculosis was related to their clinical state. Those with cavitating pulmonary disease or lymph node tuberculosis generated PPD specific lymphocytes with cytotoxic ability similar to that of those from Mantoux positive control subjects, whereas lymphocytes from patients with non-cavitating pulmonary infiltrates showed poor antigen specific cytolysis. After seven days of stimulation with PPD in vitro, lymphoblasts contained both CD4+ and CD8+ cells. Mycobacterial antigen specific cytolysis was restricted to the CD4+ cell population and was blocked by monoclonal antibodies directed against major histocompatibility class II (MHC) antigens.

CONCLUSION

CD4+ cytolytic T cells can lyse autologous macrophages presenting mycobacterial antigen and were found in patients with cavitating pulmonary tuberculosis or tuberculous lymphadenitis and in normal, Mantoux positive control subjects. The ability to generate these T cell responses seems to be a marker for response to mycobacteria and may contribute to tissue damage in tuberculosis. These responses do not provide protective immunity against Mycobacterium tuberculosis but may help in disease localisation.

Limiting dilution analysis in leprosy

Peripheral blood mononuclear cells (PBM) obtained from leprosy patients and healthy controls were cultured with Mycobacterium leprae and the control antigens, BCG and SKSD. Parallel cultures were supplemented with additional interleukin-2 (IL-2). On the basis of the level of response to M. leprae, leprosy patients could be divided into low, intermediate and high responders. The addition of IL-2 resulted in enhanced proliferation to antigen only by cells from intermediate responders. This effect was neither antigen specific nor was it confined to cells from leprosy patients. When limiting dilution analyses were performed on cells from 26 patients across the leprosy spectrum, no M. leprae-reactive lymphocytes were detected in cells from subjects with lepromatous disease. The precursor frequency for cultures containing M. leprae plus IL-2 was no greater than that of cultures containing IL-2 alone, thereby excluding the possibility of clonal anergy reversible with IL-2. This was observed in both untreated patients and those on long-term treatment, which made sequestration of antigen-reactive cells within leprosy lesions an unlikely explanation. On the other hand, M. leprae-reactive lymphocytes were detected in patients with tuberculoid and borderline tuberculoid disease and in two subjects with borderline lepromatous leprosy in type I reversal reaction. IL-2 reactive cells were detected in all patients regardless of clinical classification. Three 'suppressor' curves were obtained but were not confined to cells from lepromatous patients. Taken together, these findings suggest that the non-responsiveness to M. leprae characteristic of the great majority of multibacillary patients is due to an absence of antigen-sensitive T cells.

Rational immunotherapy with interleukin 2

Interleukin 2 (IL-2), a T lymphocyte product released upon antigen stimulation, has been used for cancer therapy in high doses for more than five years. More recently, its potential as a stimulant of cell-mediated immunity in infectious diseases, particularly those caused by intracellular microbes, has become appreciated. Drawing on the extensive information available as to the structure, cellular and molecular effects of IL-2, this review focuses on its use in patients with lepromatous leprosy and AIDS in low, physiologic doses. The data indicate that IL-2 is effective in stimulating cell-mediated immunity without systemic toxicity.

Use of serum antibody and lysozyme levels for diagnosis of leprosy and tuberculosis

Active tuberculosis (TB) and leprosy are difficult to diagnose early because there are few organisms to detect and the specific immune response does not distinguish between active and inactive disease. We developed an immunoassay for lysozyme to see whether serum lysozyme levels could be used to identify individuals with clinical leprosy or TB. The immunoassay for lysozyme proved superior to standard enzyme assays that were less sensitive and reliable. The lysozyme assay was compared with assays for antibodies to Mycobacterium tuberculosis lipoarabinomannan (LAM) and M. leprae phenolic glycolipid-1. The sera tested were from Ethiopian leprosy (paucibacillary and multibacillary) and TB patients and from healthy Ethiopian and U.S. controls. The lysozyme assay was able to detect more of the individuals with TB (sensitivity, 100% for 19 patients) or leprosy (sensitivity, 86% for 36 patients) than either antibody assay. In particular, lysozyme levels were raised in a higher proportion of the paucibacillary leprosy patients (83% of 17), for whom the antibody assays were less sensitive; the LAM IgG and the phenolic glycolipid-1 IgM levels were raised in only 62 and 44% of 16 patients, respectively. The data suggest that lysozyme measurements may be useful in the diagnosis of mycobacterial infections and other chronic infectious granulomatoses.