In vitro characterization of T cells from Mycobacterium w-vaccinated mice

A multicentre, double-blind, placebo-controlled randomized trial of Mycobacterium w in critically ill patients with COVID-19 (ARMY-2)

BACKGROUND

Mycobacterium w (Mw), an immunomodulator, resulted in better clinical status in severe coronavirus infectious disease 19 (COVID-19) but no survival benefit in a previous study. Herein, we investigate whether Mw could improve clinical outcomes and survival in COVID-19.

MATERIALS AND METHODS

In a multicentric, randomized, double-blind, parallel-group, placebo-controlled trial, we randomized hospitalized subjects with severe COVID-19 to receive either 0.3 mL/day of Mw intradermally or a matching placebo for three consecutive days. The primary outcome was 28-day mortality. The co-primary outcome was the distribution of clinical status assessed on a seven-point ordinal scale ranging from discharged (category 1) to death (category 7) on study days 14, 21, and 28. The key secondary outcomes were the change in sequential organ failure assessment (SOFA) score on days 7 and 14 compared to the baseline, treatment-emergent adverse events, and others.

RESULTS

We included 273 subjects (136 Mw, 137 placebo). The use of Mw did not improve 28-day survival (Mw vs. placebo, 18 [13.2%] vs. 12 [8.8%], P = 0.259) or the clinical status on days 14 (odds ratio [OR], 1.33; 95% confidence intervals [CI], 0.79-2.3), 21 (OR, 1.49; 95% CI, 0.83-2.7) or 28 (OR, 1.49; 95% CI, 0.79-2.8) between the two study arms. There was no difference in the delta SOFA score or other secondary outcomes between the two groups. We observed higher injection site reactions with Mw.

CONCLUSION

Mw did not reduce 28-day mortality or improve clinical status on days 14, 21 and 28 compared to placebo in patients with severe COVID-19. [Trial identifier: CTRI/2020/04/024846].

Repurposing of Mycobacterium indicus pranii for the severe form of COVID -19 patients in India: A cohort study

SARS-CoV-2 induces the production of proinflammatory cytokines, which results in cytokine storm, and immune-modulators like Mycobacterium indicus pranii (MIP) might ameliorate COVID -19 related cytokine storm. Therefore, the present study evaluates whether MIP offers an advantage in the treatment of severe COVID -19 patients infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Prospective MIP cohort Study was conducted in chest disease hospitals in Srinagar, Jammu and Kashmir, India. In the present prospective, randomized clinical study, critically severe COVID -19 patients were divided into two groups, the MIP group (n=105) and Best Standard Treatment group (n=210). Procalcitonin, Ferritin, Hs-CRP (High Sensitive C Reactive Protein), D-dimer levels and Interleukin levels on 5^th -day post-treatment were significantly reduced in the MIP group compared to the BST group. Compared to the BST group, 105 consecutive patients with severe COVID -19 in the MIP group reported early weaning off mechanical ventilation, resolution of chest architecture (CT scan), significant increase in SpO₂ levels and decreased mortality with hazard ratio-0.234 (95% CI-0.264-2.31) (p-value-0.001). MIP restored SpO₂ , immune/inflammatory response, normalized lung abnormalities (Chest CT scan), and reduced mortality without any serious complications. However, there is a need for placebo-controlled double-blind and controlled clinical trials to confirm the efficacy. This article is protected by copyright. All rights reserved.

A randomised trial of Mycobacterium w in critically ill patients with COVID-19: ARMY-1

PURPOSE

We investigated whether Mycobacterium w (Mw), an immunomodulator, would improve clinical outcomes in coronavirus disease 2019 (COVID-19).

METHODS

We conducted an exploratory, randomised, double-blind, placebo-controlled trial of hospitalised subjects with severe COVID-19 (pulmonary infiltrates and oxygen saturation ≤94% on room air) conducted at four tertiary care centres in India. Patients were randomised 1:1 to receive either 0.3 mL·day^-1 of Mw intradermally or a matching placebo for three consecutive days. The primary outcome of the study was the distribution of clinical status assessed on a seven-point ordinal scale ranging from discharged (category 1) to death (category 7) on study days 14, 21, and 28. The co-primary outcome was a change in SOFA (sequential organ failure assessment) score on days 7 and 14 compared to the baseline. The secondary outcomes were 28-day mortality, time to clinical recovery, time to reverse transcription PCR negativity, adverse events, and others.

RESULTS

We included 42 subjects (22 Mw, 20 placebo). On days 14 (OR 30.4 (95% CI 3.3-276.4)) and 21 (OR 14.9 (95% CI 1.8-128.4)), subjects in the Mw arm had a better clinical status distribution than placebo. There was no difference in the SOFA score change on days 7 and 14 between the two groups. We did not find any difference in the mortality, or other secondary outcomes. We observed no adverse events related to the use of Mw.

CONCLUSIONS

The use of Mw results in better clinical status distribution on days 14 and 21 compared to placebo in critically ill patients with COVID-19.

Potential of adjunctive Mycobacterium w (MIP) immunotherapy in reducing the duration of standard chemotherapy against tuberculosis

INTRODUCTION

The need to shorten the treatment duration in tuberculosis has always been felt. Immunotherapy in combination with chemotherapy has been considered a promising approach for this purpose into tuberculosis. We studied the adjuvant immunotherapeutic activity of Mycobacterium indicus pranii (MIP or Mw) in combination with conventional chemotherapy using guinea pig of pulmonary tuberculosis infected with Mycobacterium tuberculosis H37Rv via aerosol.

METHODS

Experimental animals treated with standard chemotherapy and immunotherapy (MIP) separately and in combination of both. Guinea pig lungs evaluated following infection and subsequent therapy at predefine time point. Various cytokine mRNA expressions levels were quantified by quantitative reverse transcriptase PCR at the 4th, 8th and 12th week post-infection of M. tuberculosis.

RESULTS

We determined the time required for bacterial clearance from guinea pig lungs. Standard chemotherapy (RvCh) compared to the animals where chemotherapy plus Mw immunotherpay (RvChMwT) was given. It took 12 weeks to achieve bacterial clearance in the RvCh group while this was achieved in 8 weeks in RvChMwT group. Pro-inflammatory cytokines (IFN-γ, IL-2, IL-12p35 and TNF-α) level were higher in RvCh, RvChMwT and RvMwT group, while the IL-10 and TGF-β were suppressed.

CONCLUSION

Cytokine expression level showed that Mw in conjunction with chemotherapy enhances the effect of pro-inflammatory cytokines (such as, IFN-γ, IL-2, IL-12 and TNF-α) and reduces the production and effect of anti-inflammatory cytokines (like IL-10 and TGF-β) thereby restoring the pro-inflammatory / anti-inflammatory cytokines balance. Thus, the present study indicates that subject to rigorous testing by other parameters, Mw (MIP) as adjunct immunotherapy has potential for reducing treatment duration.

Interventions for treating tuberculous pericarditis

BACKGROUND

Tuberculous pericarditis can impair the heart's function and cause death; long term, it can cause the membrane to fibrose and constrict causing heart failure. In addition to antituberculous chemotherapy, treatments include corticosteroids, drainage, and surgery.

OBJECTIVES

To assess the effects of treatments for tuberculous pericarditis.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register (27 March 2017); the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library (2017, Issue 2); MEDLINE (1966 to 27 March 2017); Embase (1974 to 27 March 2017); and LILACS (1982 to 27 March 2017). In addition we searched the metaRegister of Controlled Trials (mRCT) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal using 'tuberculosis' and 'pericard*' as search terms on 27 March 2017. We searched ClinicalTrials.gov and contacted researchers in the field of tuberculous pericarditis. This is a new version of the original 2002 review.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search outputs, evaluated study eligibility, assessed risk of bias, and extracted data; and we resolved any discrepancies by discussion and consensus. One trial assessed the effects of both corticosteroid and Mycobacterium indicus pranii treatment in a two-by-two factorial design; we excluded data from the group that received both interventions. We conducted fixed-effect meta-analysis and assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Seven trials met the inclusion criteria; all were from sub-Saharan Africa and included 1959 participants, with 1051/1959 (54%) HIV-positive. All trials evaluated corticosteroids and one each evaluated colchicine, M. indicus pranii immunotherapy, and open surgical drainage. Four trials (1841 participants) were at low risk of bias, and three trials (118 participants) were at high risk of bias.In people who are not infected with HIV, corticosteroids may reduce deaths from all causes (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.59 to 1.09; 660 participants, 4 trials, low certainty evidence) and the need for repeat pericardiocentesis (RR 0.85, 95% CI 0.70 to 1.04; 492 participants, 2 trials, low certainty evidence). Corticosteroids probably reduce deaths from pericarditis (RR 0.39, 95% CI 0.19 to 0.80; 660 participants, 4 trials, moderate certainty evidence). However, we do not know whether or not corticosteroids have an effect on constriction or cancer among HIV-negative people (very low certainty evidence).In people living with HIV, only 19.9% (203/1959) were on antiretroviral drugs. Corticosteroids may reduce constriction (RR 0.55, 0.26 to 1.16; 575 participants, 3 trials, low certainty evidence). It is uncertain whether corticosteroids have an effect on all-cause death or cancer (very low certainty evidence); and may have little or no effect on repeat pericardiocentesis (RR 1.02, 0.89 to 1.18; 517 participants, 2 trials, low certainty evidence).For colchicine among people living with HIV, we found one small trial (33 participants) which had insufficient data to make any conclusions about any effects on death or constrictive pericarditis.Irrespective of HIV status, due to very low certainty evidence from one trial, it is uncertain whether adding M. indicus pranii immunotherapy to antituberculous drugs has an effect on any outcome.Open surgical drainage for effusion may reduce repeat pericardiocentesis In HIV-negative people (RR 0.23, 95% CI 0.07 to 0.76; 122 participants, 1 trial, low certainty evidence) but may make little or no difference to other outcomes. We did not find an eligible trial that assessed the effects of open surgical drainage in people living with HIV.The review authors found no eligible trials that examined the length of antituberculous treatment needed nor the effects of other adjunctive treatments for tuberculous pericarditis.

AUTHORS' CONCLUSIONS

For HIV-negative patients, corticosteroids may reduce death. For HIV-positive patients not on antiretroviral drugs, corticosteroids may reduce constriction. For HIV-positive patients with good antiretroviral drug viral suppression, clinicians may consider the results from HIV-negative patients more relevant.Further research may help evaluate percutaneous drainage of the pericardium under local anaesthesia, the timing of pericardiectomy in tuberculous constrictive pericarditis, and new antibiotic regimens.

Immunodominant protein MIP_05962 from Mycobacterium indicus pranii displays chaperone activity

Tuberculosis, a contagious disease of infectious origin is currently a major cause of deaths worldwide. Mycobacterium indicus pranii (MIP), a saprophytic nonpathogen and a potent immunomodulator is currently being investigated as an intervention against tuberculosis along with many other diseases with positive outcome. The apparent paradox of multiple chaperones in mycobacterial species and enigma about the cellular functions of the client proteins of these chaperones need to be explored. Chaperones are the known immunomodulators; thus, there is need to exploit the proteome of MIP for identification and characterization of putative chaperones. One of the immunogenic proteins, MIP_05962 is a member of heat shock protein (HSP) 20 family due to the presence of α-crystallin domain, and has amino acid similarity with Mycobacterium lepraeHSP18 protein. The diverse functions of M. lepraeHSP18 in stress conditions implicate MIP_05962 as an important protein that needs to be explored. Biophysical and biochemical characterization of the said protein proved it to be a chaperone. The observations of aggregation prevention and refolding of substrate proteins in the presence of MIP_05962 along with interaction with non-native proteins, surface hydrophobicity, formation of large oligomers, in-vivo thermal rescue of Escherichia coli expressing MIP_05962, enhancing solubility of insoluble protein maltodextrin glucosidase (MalZ) under in-vivo conditions, and thermal stability and reversibility confirmed MIP_05962 as a molecular chaperone.

Inter-Clade Protection Offered by Mw-Adjuvanted Recombinant HA, NP Proteins, and M2e Peptide Combination Vaccine in Mice Correlates with Cellular Immune Response

We documented earlier that Mw (heat-killed suspension of Mycobacterium indicus pranii) adjuvant when used with conserved antigens, nucleoprotein (NP), and ectodomain of matrix (M2) protein (M2e) provided complete protection against homologous (clade 2.2) virus challenge in mice. The present study extends these observations to inter-clade challenge (clade 2.3.2.1) H5N1 virus and attempts to understand preliminary immunologic basis for the observed protection. Female BALB/c mice immunized with a single or two doses of vaccine formulations (clade 2.2 antigens) were challenged with 100LD50 homologous or heterologous (clade 2.3.2.1) virus. To understand the preliminary immunologic mechanism, we studied proportions of selected immune cell types, immune response gene expression, and Th1/Th2 cytokines induced by antigen-stimulated splenocytes from immunized mice, at different time points. Complete protection was conferred by Mw-HA, Mw-HA + NP, and Mw-HA + NP + M2e against homologous challenge. The protection correlated with IgG2a antibody titers indicating important role of Th1 response. Despite high inter-cladal antigenic differences, complete protection against the heterologous strain was achieved with Mw-HA + NP + M2e. Of note, a single dose with higher antigen concentrations (50 µg HA + 50 μg NP + 50 μg M2e) led to 80% protection against clade 2.3.2.1 strain. The protection conferred by Mw-HNM correlated with induction of IFN-γ, CD8⁺ T cytotoxic cells, and CD4⁺ T helper cells. Mw-adjuvanted HA + NP + M2e combination represents a promising vaccine candidate deserving further evaluation.

Efficacy of intralesional immunotherapy for the treatment of warts: A review of the literature

Warts are common epidermal growths caused by human papillomavirus that often cause significant discomfort and embarrassment. Current treatment options include topical therapies, cryotherapy, laser vaporization, and surgical excision. Many of these options are destructive and may result in scarring, while less aggressive approaches can lead to lesion recurrence. Additionally, these local modalities are not practical for patients with a large number of warts. Systemic approaches such as immunotherapy have demonstrated success in treating multiple lesions by combining a targeted approach with upregulation of the host immune system. An extensive literature review was performed to evaluate the various vaccine antigens that have been used intralesionally to treat cutaneous and anogenital warts. The specific intralesional immunotherapies that have been studied include: Candida albicans; measles, mumps, and rubella; Trichophyton; and tuberculin antigens such as purified protein derivative, Mycobacterium w vaccine, and Bacillus Calmette-Guerin. Intralesional vaccine injection represents a safe, effective, and tolerable treatment for warts, including recalcitrant and anogenital warts. This approach has been somewhat overlooked in the past despite substantial evidence of high response rates with a low side effect profile. Large comparative trials are necessary to determine the most effective immunotherapy treatment option as well as the most appropriate dosing parameters.

Intralesional immunotherapy for difficult to treat warts with Mycobacterium w vaccine

Background:

Immunotherapy is an evolving therapeutic modality for the treatment of warts. We conducted a study to assess the efficacy and safety of intralesional Mycobacterium w vaccine for the treatment of warts at sites that were difficult to treat.

Materials and Methods:

Thirty patients with at least one wart present on either the plantar surface of their feet, palms, volar aspect of their fingers, or periungual or subungual region, were treated with 0.1 ml of killed Mycobacterium w vaccine given intralesionally in a single wart, without any prior sensitisation dose. Thereafter, a single injection of 0.1 ml of vaccine was given at intervals of four weeks in a single wart till there was complete resolution of the warts or a maximum of 10 injections. Treatment was stopped if there was no response after three injections. The patients were followed up for at least six months.

Results:

Out of the 30 patients, 28 (93.33%) patients had complete resolution of their warts, both at the injected and distant sites. The mean (SD) time for complete clearance of warts was 43.71(32.82) days and the mean (SD) dose of vaccine that was required for complete clearance of warts was 0.186 ml (0.101). Four patients (14.28%) had a recurrence of warts. The treatment was well-tolerated and the side effects were reversible in the majority of the patients.

Conclusion:

In comparison to the earlier studies using Mycobacterium w vaccine for the treatment of warts, our study was different in the following aspects: No sensitisation dose was given, only a single wart was injected at a time and the duration between the period of injections was increased to four weeks. With all these changes we eliminated the complications due to the sensitisation dose and achieved good results. This study provides new insight into the dose and schedule of treatment of this evolving therapeutic modality.

Unresponsiveness of Mycobacterium w vaccine in managing acute and chronic Leishmania donovani infections in mouse and hamster

The role of Mycobacterium w (Mw) vaccine as an immunomodulator and immunoprophylactant in the treatment of mycobacterial diseases (leprosy and pulmonary tuberculosis) is well established. The fact that it shares common antigens with leishmanial parasites prompted its assessment as an immunostimulant and as an adjunct to known anti-leishmanials that may help in stimulating the suppressed immune status of Leishmania donovani-infected individuals. The efficacy of Mw vaccine was assessed as an immunomodulator, prophylactically either alone or in combination with anti-leishmanial vaccine, as well as therapeutically as an adjunct to anti-leishmanial treatment in L. donovani-infected hamsters, representing a chronic human Visceral Leishmaniasis (VL) model. Similarly, its efficacy was also evaluated in L. donovani-infected BALB/c mice, representing an acute VL model. The preliminary studies revealed that Mw was ineffective as an immunostimulant and/or immunoprophylactant in hamsters infected with L. donovani, as estimated by T-cell immunological responses. However, in the BALB/c mice-VL model it appeared as an effective immunostimulant but a futile prophylactic agent. It is therefore inferred that, contrary to its role in managing tuberculosis and leprosy infections, Mw vaccine has not been successful in controlling VL infection, emphasizing the need to find detailed explanations for the failure of this vaccine against the disease.

Massive gene acquisitions in Mycobacterium indicus pranii provide a perspective on mycobacterial evolution

Understanding the evolutionary and genomic mechanisms responsible for turning the soil-derived saprophytic mycobacteria into lethal intracellular pathogens is a critical step towards the development of strategies for the control of mycobacterial diseases. In this context, Mycobacterium indicus pranii (MIP) is of specific interest because of its unique immunological and evolutionary significance. Evolutionarily, it is the progenitor of opportunistic pathogens belonging to M. avium complex and is endowed with features that place it between saprophytic and pathogenic species. Herein, we have sequenced the complete MIP genome to understand its unique life style, basis of immunomodulation and habitat diversification in mycobacteria. As a case of massive gene acquisitions, 50.5% of MIP open reading frames (ORFs) are laterally acquired. We show, for the first time for Mycobacterium, that MIP genome has mosaic architecture. These gene acquisitions have led to the enrichment of selected gene families critical to MIP physiology. Comparative genomic analysis indicates a higher antigenic potential of MIP imparting it a unique ability for immunomodulation. Besides, it also suggests an important role of genomic fluidity in habitat diversification within mycobacteria and provides a unique view of evolutionary divergence and putative bottlenecks that might have eventually led to intracellular survival and pathogenic attributes in mycobacteria.

Mycobacterium indicus pranii mediates macrophage activation through TLR2 and NOD2 in a MyD88 dependent manner

Mycobacterium indicus pranii (MIP) is a non-pathogenic strain of mycobacterium and has been used as a vaccine against tuberculosis and leprosy. Here, we investigated the role of different pattern recognition receptors in the recognition of heat-killed MIP by macrophages. Treatment of macrophages with MIP caused upregulation of pro-inflammatory cytokines (like TNFα and IL-1β) which was mediated through both TLR2 and NOD2, as revealed by our knockdown and/or knockout studies. Mechanistically, MIP-induced macrophage activation was shown to result in NF-κB activation and drastically abrogated by MyD88 deficiency, suggesting its regulation via an MyD88-dependent, NF-κB pathway. Interestingly, the IFN-inducible cytokine, CXCL10, which is known target of the TRIF-dependent TLR pathway was found to be upregulated in response to MIP but, in an MyD88-dependent manner. Collectively, these results demonstrate macrophages to recognize and respond to MIP through a TLR2, NOD2 and an MyD88-dependent pathway. However, further studies should clarify whether additional TLR-dependent or -independent pathways also exist in regulating the full spectrum of MIP action on macrophage activation.

Mycobacterium indicus pranii (Mw) re-establishes host protective immune response in Leishmania donovani infected macrophages: critical role of IL-12

Leishmania donovani, a protozoan parasite, causes a strong immunosuppression in a susceptible host and inflicts the fatal disease visceral leishmaniasis. Relatively high toxicity, low therapeutic index, and failure in reinstating host-protective anti-leishmanial immune responses have made anti-leishmanial drugs patient non-compliant and an immuno-modulatory treatment a necessity. Therefore, we have tested the anti-leishmanial efficacy of a combination of a novel immunomodulator, Mycobacterium indicus pranii (Mw), and an anti-leishmanial drug, Amphotericin B (AmpB). We observe that Mw alone or with a suboptimal dose of AmpB offers significant protection against L. donovani infection by activating the macrophages. Our experiments examining the anti-leishmanial activity of Mw alone or with AmpB also indicate a p38MAPK and ERK-1/2 regulated pro-inflammatory responses. The Mw-AmpB combination induced nitric oxide production, restored Th1 response, and significantly reduced parasite burden in wild type macrophages but not in IL-12-deficient macrophages indicating a pivotal role for IL-12 in the induction of host-protection by Mw and AmpB treatments. In addition, we observed that Mw alone or in combination with suboptimal dose of AmpB render protection against L. donovani infection in susceptible BALB/c mice. However, these treatments failed to render protection in IL-12-deficient mice in vivo which added further support that IL-12 played a central role in this chemo immunotherapeutic approach. Thus, we demonstrate a novel chemo-immunotherapeutic approach- Mw and AmpB crosstalk eliminating the parasite-induced immunosuppression and inducing collateral host-protective effects.

Immunotherapeutic efficacy of Mycobacterium indicus pranii in eliciting anti-tumor T cell responses: critical roles of IFNγ

Mycobacterium indicus pranii (MIP) is approved for use as an adjuvant (Immuvac/Cadi-05) in the treatment of leprosy. In addition, its efficacy is being investigated in clinical trials on patients with tuberculosis and different tumors. To evaluate and delineate the mechanisms by which autoclaved MIP enhances anti-tumor responses, the growth of solid tumors consisting of Sp2/0 (myeloma) and EL4 (thymoma) cells was studied in BALB/c and C57BL/6 mice, respectively. Treatment of mice with a single intra-dermal (i.d.) injection of MIP 3 days after Sp2/0 implantation greatly suppresses tumor growth. MIP treatment of tumor bearing mice lowers Interleukin (IL)6 but increases IL12p70 and IFNγ amounts in sera. Also, increase in CD8(+) T cell mediated lysis of specific tumor targets and production of high amounts of IL2 and IFNγ by CD4(+) T cells upon stimulation with specific tumor antigens in MIP treated mice is observed. Furthermore, MIP is also effective in reducing the growth of EL4 tumors; however, this efficacy is reduced in Ifnγ(-/-) mice. In fact, several MIP mediated anti-tumor responses are greatly abrogated in Ifnγ(-/-) mice: increase in serum Interleukin (IL)12p70 amounts, induction of IL2 and lysis of EL4 targets by splenocytes upon stimulation with specific tumor antigens. Interestingly, tumor-induced increase in serum IL12p70 and IFNγ and reduction in growth of Sp2/0 and EL4 tumors by MIP are not observed in nonobese diabetic severe combined immunodeficiency mice. Overall, our study clearly demonstrates the importance of a functional immune network, in particular endogenous CD4(+) and CD8(+) T cells and IFNγ, in mediating the anti-tumor responses by MIP.

Mycobacterium indicus pranii supernatant induces apoptotic cell death in mouse peritoneal macrophages in vitro

Mycobacterium indicus pranii (MIP), also known as Mw, is a saprophytic, non-pathogenic strain of Mycobacterium and is commercially available as a heat-killed vaccine for leprosy and recently tuberculosis (TB) as part of MDT. In this study we provide evidence that cell-free supernatant collected from original MIP suspension induces rapid and enhanced apoptosis in mouse peritoneal macrophages in vitro. It is demonstrated that the MIP cell-free supernatant induced apoptosis is mitochondria-mediated and caspase independent and involves mitochondrial translocation of Bax and subsequent release of AIF and cytochrome c from the mitochondria. Experiments with pharmacological inhibitors suggest a possible role of PKC in mitochondria-mediated apoptosis of macrophages.

Polyphasic taxonomic analysis establishes Mycobacterium indicus pranii as a distinct species

Background

Mycobacterium indicus pranii (MIP), popularly known as Mw, is a cultivable, non-pathogenic organism, which, based on its growth and metabolic properties, is classified in Runyon Group IV along with M. fortuitum, M. smegmatis and M. vaccae. The novelty of this bacterium was accredited to its immunological ability to undergo antigen driven blast transformation of leukocytes and delayed hypersensitivity skin test in leprosy patients, a disease endemic in the Indian sub-continent. Consequently, MIP has been extensively evaluated for its biochemical and immunological properties leading to its usage as an immunomodulator in leprosy and tuberculosis patients. However, owing to advances in sequencing and culture techniques, the citing of new strains with almost 100% similarity in the sequences of marker genes like 16S rRNA, has compromised the identity of MIP as a novel species. Hence, to define its precise taxonomic position, we have carried out polyphasic taxonomic studies on MIP that integrate its phenotypic, chemotaxonomic and molecular phylogenetic attributes.

Methodology/Principal Findings

The comparative analysis of 16S rRNA sequence of MIP by using BLAST algorithm at NCBI (nr database) revealed a similarity of ≥99% with M. intracellulare, M. arosiense, M. chimaera, M. seoulense, M. avium subsp. hominissuis, M. avium subsp. paratuberculosis and M. bohemicum. Further analysis with other widely used markers like rpoB and hsp65 could resolve the phylogenetic relationship between MIP and other closely related mycobacteria apart from M. intracellulare and M. chimaera, which shares ≥99% similarity with corresponding MIP orthologues. Molecular phylogenetic analysis, based on the concatenation of candidate orthologues of 16S rRNA, hsp65 and rpoB, also substantiated its distinctiveness from all the related organisms used in the analysis excluding M. intracellulare and M. chimaera with which it exhibited a close proximity. This necessitated further analysis of MIP with more sensitive and segregating parameters to ascertain its precise taxonomic position as a new species. The analysis of MIP and its comparison with other mycobacterial reference strains based on cellular and biochemical features, growth characteristics and chemotaxonomic studies like FAME profiling confirmed that MIP is uniquely endowed with diverse metabolic attributes that effectively distinguishes it from all the closely related mycobacteria including M. intracellulare and M. chimaera.

Conclusion

The results presented in this study coupled with the non-pathogenic nature and different biochemical and immunomodulatory properties of MIP affirm it as a distinct species belonging to M. avium complex (MAC). It is further proposed to use an earlier suggested name Mycobacterium indicus pranii for this newly established mycobacterial species. This study also exemplifies the growing need for a uniform, consensus based broader polyphasic frame work for the purpose of taxonomy and speciation, particularly in the genus Mycobacterium.

Immunogenicity and protective efficacy of "Mycobacterium w" against Mycobacterium tuberculosis in mice immunized with live versus heat-killed M. w by the aerosol or parenteral route

As the disease caused by Mycobacterium tuberculosis continues to be a burden, there is a concerted effort to find new vaccines to combat this problem. One of the important vaccine strategies is whole bacterial vaccines. This approach relies on multiple antigens and built-in adjuvanticity. Other mycobacterial strains which share cross-reactive antigens with M. tuberculosis have been considered as alternatives to M. bovis for vaccine use. One such strain, "Mycobacterium w", had been evaluated for its immunomodulatory properties in leprosy. A vaccine against leprosy based on killed M. w is approved for human use, where it has resulted in clinical improvement, accelerated bacterial clearance, and increased immune responses to Mycobacterium leprae antigens. M. w shares antigens not only with M. leprae but also with M. tuberculosis, and initial studies have shown that vaccination with killed M. w induces protection against tuberculosis in Mycobacterium bovis BCG responder, as well as BCG nonresponder, strains of mice. Hence, we further studied the protective potential of M. w and the underlying immune responses in the mouse model of tuberculosis. We analyzed the protective efficacy of M. w immunization in both live and killed forms through the parenteral route and by aerosol immunization, compared with that of BCG. Our findings provide evidence that M. w has potential protective efficacy against M. tuberculosis. M. w activates macrophage activity, as well as lymphocytes. M. w immunization by both the parenteral route and aerosol administration gives higher protection than BCG given by the parenteral route in the mouse model of tuberculosis.

Intralesional immunotherapy with killed Mycobacterium w vaccine for the treatment of ano-genital warts: an open label pilot study

BACKGROUND

Intralesional immunotherapy with skin test antigens and vaccines has been found to be effective in the management of genital and extragenital warts.

OBJECTIVE

To evaluate the efficacy and safety of intralesional Mycobacterium w (Mw) vaccine monotherapy for the treatment of ano-genital warts.

PATIENTS AND METHODS

Ten patients clinically diagnosed to have external ano-genital warts, including three with giant ano-genital warts (Buschke Löwenstein tumour), were included in this open-label pilot study. Two patients were human immunodeficiency virus seropositive, and one was on iatrogenic immunosuppression for renal transplantation. Mw vaccine (0.1 mL) was initially injected intradermally in the deltoid region on both the sides, followed 2 weeks later by intradermal intralesional injection into the genital warts. Intralesional injections were repeated weekly until either complete clearance or a maximum of 10 injections was achieved.

RESULTS

One patient was lost to follow-up after the first intralesional injection. In 8 out of remaining 9 patients (88.9%), the genital warts cleared completely. In one patient with giant perianal wart, the lesion was reduced to less than 5% of its volume after 10 intralesional injections, which was later electrosurgically excised. The treatment was well tolerated by the majority of the patients. The adverse reactions were noted in four patients, which were reversible. No recurrence was seen after a mean follow-up of 5.1 months.

CONCLUSION

Intralesional immunotherapy of ano-genital warts with Mw vaccine seems to be a promising new approach, which needs to be evaluated in the randomized controlled trials.

Molecular analysis of a leprosy immunotherapeutic bacillus provides insights into Mycobacterium evolution

Background

Evolutionary dynamics plays a central role in facilitating the mechanisms of species divergence among pathogenic and saprophytic mycobacteria. The ability of mycobacteria to colonize hosts, to proliferate and to cause diseases has evolved due to its predisposition to various evolutionary forces acting over a period of time. Mycobacterium indicus pranii (MIP), a taxonomically unknown ‘generalist’ mycobacterium, acts as an immunotherapeutic against leprosy and is approved for use as a vaccine against it. The large-scale field trials of this MIP based leprosy vaccine coupled with its demonstrated immunomodulatory and adjuvant property has led to human clinical evaluations of MIP in interventions against HIV-AIDS, psoriasis and bladder cancer. MIP, commercially available as ‘Immuvac’, is currently the focus of advanced phase III clinical trials for its antituberculosis efficacy. Thus a comprehensive analysis of MIP vis-à-vis evolutionary path, underpinning its immanent immunomodulating properties is of the highest desiderata.

Principal Findings

Genome wide comparisons together with molecular phylogenetic analyses by fluorescent amplified fragment length polymorphism (FAFLP), enterobacterial repetitive intergenic consensus (ERIC) based genotyping and candidate orthologues sequencing revealed that MIP has been the predecessor of highly pathogenic Mycobacterium avium intracellulare complex (MAIC) that did not resort to parasitic adaptation by reductional gene evolution and therefore, preferred a free living life-style. Further analysis suggested a shared aquatic phase of MAIC bacilli with the early pathogenic forms of Mycobacterium, well before the latter diverged as ‘specialists’.

Conclusions/Significance

This evolutionary paradigm possibly affirms to marshal our understanding about the acquisition and optimization of virulence in mycobacteria and determinants of boundaries therein.

Large-scale validation of a latex agglutination test for diagnosis of tuberculosis

Large-scale validation of a simple latex agglutination test for the diagnosis of tuberculosis is described. Soluble antigens extracted from a non-pathogenic saprophytic mycobacterium, Mycobacterium w, which shares antigenic determinants with Mycobacterium tuberculosis, were covalently linked to carboxylated polystyrene latex beads. Batch to batch reproducibility of coated latex was ensured. Latex reagents were standardized to overcome non-specific agglutination. Reagents of the test are stable for 1 year at 4 degrees C. A total of 1,058 serum samples of pulmonary and extrapulmonary tuberculosis patients or patients with other pulmonary diseases and healthy controls living in endemic areas were tested. Sensitivity of 94% for pulmonary tuberculosis and 87% for extrapulmonary tuberculosis was obtained. Specificity is 92.2% for healthy controls and patients with other respiratory diseases. We conclude that the latex agglutination test can be utilized for mass screening for both pulmonary and extrapulmonary tuberculosis where diagnosis by existing methods is much more difficult.

Recent advances in tuberculosis research in India

Tuberculosis (TB) continues to be the leading killer of mankind among all infectious diseases, especially in the developing countries. Since the discovery of tubercle bacillus more than 100 years ago, TB has been the subject of research in an attempt to develop tools and strategies to combat this disease. Research in Indian laboratories has contributed significantly towards developing the DOTS strategy employed worldwide in tuberculosis control programmes and elucidating the biological properties of its etiologic agent, M. tuberculosis. In recent times, the development of tools for manipulation of mycobacteria has given a boost to researchers working in this field. New strategies are being employed towards understanding the mechanisms of protection and pathogenesis of this disease. Molecular methods are being applied to develop new tools and reagents for prevention, diagnosis and treatment of tuberculosis. With the sequencing of the genome of M. tuberculosis, molecules are being identified for the development of new drugs and vaccines. In this chapter, the advances made in these areas by Indian researchers mainly during the last five years are reviewed.

Mice immune responses to Brucella abortus heat shock proteins. Use of baculovirus recombinant-expressing whole insect cells, purified Brucella abortus recombinant proteins, and a vaccinia virus recombinant as immunogens

Brucella abortus resists the microbicidal mechanisms of macrophages, and the expression of its heat shock proteins (HSPs) such as GroEL, GroES and HtrA may play a role in this resistance. Bacterial HSPs can be very immunogenic, inducing protective immunity in various types of bacterial infections. However, the significance of immune responses directed against B. abortus HSPs in the protection against brucellosis is currently unresolved. To elucidate the role of these proteins in protection against Brucella challenge, individual, divalent or trivalent baculovirus (BV) recombinants of B. abortus GroEL, GroES and/or HtrA were injected into BALB/c mice either as protein-expressing whole cells or as purified proteins. The preparations were given to mice in combination with Freund's or Ribi adjuvant, respectively. In addition, some mice were primed with a vaccinia virus-GroEL recombinant, followed by inoculation with purified GroEL-Ribi adjuvant combination. Antibodies were observed against B. abortus GroEL and HtrA, but not against GroES. Cellular immune response was demonstrated by observing significant IFN-gamma release by lymphocytes of mice immunized with the purified HtrA-Ribi adjuvant combination. However, none of the mice inoculated with individual, divalent or trivalent HSP-expressing cells combined with complete Freund's adjuvant or inoculated with purified B. abortus HSPs combined with Ribi adjuvant, were protected against challenge with B. abortus virulent strain 2308. Priming with vaccinia virus-GroEL recombinant and boosting with GroEL-Ribi combination did not induce protective immunity. Based on the results obtained, we suggest that although humoral and cell-mediated immune responses are induced, but protective immune response is not induced by B. abortus HSPs.

Protective killed Leptospira borgpetersenii vaccine induces potent Th1 immunity comprising responses by CD4 and gammadelta T lymphocytes

Leptospira borgpetersenii serovar hardjo is the most common cause of bovine leptospirosis and also causes zoonotic infections of humans. A protective killed vaccine against serovar hardjo was shown to induce strong antigen-specific proliferative responses by peripheral blood mononuclear cells (PBMC) from vaccinated cattle by 2 months after the first dose of vaccine. This response was absent from nonvaccinated control cattle. The mean response peaked by 2 months after completion of the two-dose vaccination regimen, and substantial proliferation was measured in in vitro cultures throughout the 7 months of the study period. Variations in magnitude of the response occurred among the vaccinated animals, but by 7 months postvaccination there was a substantial antigen-specific response with PBMC from all vaccinated animals. Up to one-third of the PBMC from vaccinated animals produced gamma interferon (IFN-gamma) after 7 days in culture with antigen, as ascertained by flow cytometric analysis, and significant levels of IFN-gamma were measured in culture supernatants by enzyme-linked immunosorbent assay. Two-color immunofluorescence revealed that one-third of the IFN-gamma-producing cells were gammadelta T cells, with the remaining cells being CD4(+) T cells. The significance of this study is the very potent Th1-type immune response induced and sustained following vaccination with a killed bacterial vaccine adjuvanted with aluminum hydroxide and the involvement of gammadelta T cells in the response. Moreover, induction of this Th1-type cellular immune response is associated with the protection afforded by the bovine leptospiral vaccine against L. borgpetersenii serovar hardjo.

Aberrant macrophage and neutrophil population dynamics and impaired Th1 response to Listeria monocytogenes in colony-stimulating factor 1-deficient mice

Listeria monocytogenes, a facultative intracellular bacterium, has been used extensively to study innate immune responses. Macrophages act as hosts for this bacterium as well as a major defense against it. Using mice homozygous for a null mutation (Csf1(op)) in the gene for the mononuclear phagocytic growth factor colony-stimulating factor 1 (CSF-1), we have demonstrated that CSF-1-regulated macrophages were essential to defend against a listerial infection. In the absence of CSF-1, monocytes were not recruited to the sites of infection due to the lack of synthesis of the macrophage chemoattractant chemokine MCP-1. In addition, there was no burst of interleukin-10 (IL-10) synthesis that has been shown to result in the egress of neutrophils from sites of infection. Consequently, neutrophils were not replaced by macrophages, and numerous neutrophil-filled microabscesses developed, followed by tissue destruction and death of the mice. In the CSF-1 nullizygous mice compared to wild-type mice, there was also a very low synthesis of gamma interferon (IFN-gamma), resulting in reduced macrophage activation. However, the concentrations of the IFN-gamma-inducing cytokines IL-12 and IL-18 at this bacterial load were similar in these mutant mice. In contrast, IL-6 concentrations were dramatically reduced. Administration of IL-6 to Csf1(op)/Csf1(op) mice significantly increased the synthesis of IFN-gamma and reduced the bacterial burden to a greater extent than treatment with IFN-gamma alone. These data indicate that IL-6 occupies a central role in the CSF-1-regulated macrophage response to L. monocytogenes.

An immunotherapeutic vaccine for multibacillary leprosy

On January 30, 1998, a vaccine for leprosy based on Mycobacterium w (the code word under which this species hitherto unspecified was investigated) was launched for public use for therapeutic purposes. The vaccine has completed phase III immunotherapeutic trials as an adjunct to chemotherapy in urban and rural leprosy control centres and has received the authorization from the Drugs Controller of India for industrial manufacture. It will be made available by M/s Cadila Pharmaceuticals, Ahmedabad. As an adjunct to chemotherapy, the vaccine expediates bacterial clearance and accelerates clinical regression of lesions. It shortens significantly the period for release from treatment (RFT) of patients. It is effective in inducing a fall of bacterial index (BI) in multibacillary patients who are either nonresponders or slow responders to the standard multidrug therapy and who have persistent BI over long periods. An additional benefit of immunization with this vaccine is the conversion of >60% of LL, 71% of BL and 100% of BB patients from lepromin negativity to lepromin positivity status. A significant number of vaccinated patients showed histopathological upgrading and eventually attainment of a state of nonspecific infiltration without dermal granulomas. The vaccine was well tolerated and the incidence of Type 2 reactions and their severity was less in combined immuno cum chemotherapy group than in the group receiving only chemotherapy. This review describes the nature of the vaccine and the way it was developed.

Ovalbumin (OVA) and Mycobacterium tuberculosis bacilli cooperatively polarize anti-OVA T-helper (Th) cells toward a Th1-dominant phenotype and ameliorate murine tracheal eosinophilia

A recent increase in allergic disorders has coincided with a decrease in infections, including tuberculosis. Although an inverse association between tuberculin responses and atopic disorders was reported, it was not known how T-helper (Th)1-biased immune responses to Mycobacterium tuberculosis influenced Th2-dominant responses to allergens. We examined whether M. tuberculosis could modulate ovalbumin (OVA)-induced eosinophilic inflammation in the murine trachea in a manner that transcended the barrier of antigen specificity. We found that CD4(+) T cells primed with OVA in complete Freund's adjuvant (CFA) inhibited OVA-induced tracheal eosinophilia through interferon (IFN)-gamma secretion. Immunization with an irrelevant antigen in CFA or with OVA in incomplete Freund's adjuvant failed to induce suppressor cells. In vitro experiments confirmed that both M. tuberculosis and OVA (as opposed to either one alone) were necessary to evoke polarized development toward a Th1-like phenotype through interleukin-12 secretion. These results indicate that exposure to an allergen along with M. tuberculosis switches development of allergen-specific T cells toward a Th1 phenotype, which, in turn, downregulates allergic manifestations in an antigen-specific manner. The possible implications of these results are discussed in the context of the causal relationship between a decrease in tuberculosis and an increase in allergic disorders.

Effective adjuvants for the induction of antigen-specific delayed-type hypersensitivity

Vaccines utilizing poorly immunogenic subunit antigens are dependent upon adjuvants to drive the appropriate T cell responses. In an effort to determine the ability of several adjuvants to promote cell-mediated immunity (CMI), we assessed delayed-type hypersensitivity (DTH) in mice inoculated with heat-killed Listeria monocytogenes (HKLM) vaccines. The vaccines were formulated as oil-in-water emulsions containing one or more of the following bacterial-derived immunostimulators: MPL immunostimulant, a monophosphoryl lipid A preparation, synthetic trehalose dicorynomycolate (TDCM) and Mycobacterium phlei cell wall skeleton (CWS). Oil-in-water emulsions containing HKLM without adjuvants did not induce DTH responsiveness in mice. The incorporation of TDCM, or MPL plus TDCM and/or CWS to the formulation enabled the HKLM vaccine to stimulate CMI characterized by DTH responsiveness. Following antigen challenge the resulting increases in footpad thickness ranged from 15-20% and were comparable to the DTH driven by complete Freund's adjuvant. Adjuvants composed of MPL/TDCM and MPL/TDCM/CWS induced responses equivalent to those measured in mice immunized with viable L. monocytogenes, and the responses remained at these levels for at least 2 months. Furthermore, in vivo depletion of CD4+ T cells, but not CD8+ T cells, abrogated the induction and expression of DTH, indicating that the response is mediated by CD4+ T cells.

Substance P promotes lymphocyte-endothelial cell adhesion preferentially via LFA-1/ICAM-1 interactions

Substance P (SP), an 11 amino acid peptide, is released by C and A delta sensory nerve fibers during tissue insult and inflammation. We investigated the effect of SP on the expression and avidity of adhesion molecules, on lymphocytes and endothelial cells, which are central to the inflammatory cascade. Using in vitro adhesion assays we found that pretreatment of murine endothelial cells with SP enhanced their adhesiveness to splenocytes, the murine T cell hybridoma EL4 and nylon-enriched primary murine T cells in a dose and time dependent manner, the optimum dose being 10(-10) M and the optimum time 6 h. SP at 10(-10) M was also able to stimulate the splenocytes, EL4 T cells and primary T cells to enhance their adhesiveness for endothelial cells. The increased adhesiveness was associated with enhanced expression of ICAM-1 on endothelial cells and increased avidity of LFA-1 on lymphocytes. Further SP was chemotactic for T cells. These data suggest that SP modulates lymphocyte-endothelial cell interactions by preferentially upregulating LFA-1 and ICAM-1 interactions.

Slide agglutination test for the diagnosis of pulmonary and extra-pulmonary tuberculosis

OBJECTIVE

Evaluation of a 2 min slide agglutination test to detect the presence of antibodies directed against Mycobacterium tuberculosis antigens.

DESIGN

The test utilizes solible antigens extracted from a cultivable new species of non-pathogenic saprophytic mycobacterium, Mycobacterium w, which shares antigenic determinants with M. tuberculosis. The soluble antigens are covalently linked to carboxylated polystyrene latex beads.

RESULTS

The sensitivity of the assay was increased from 78% (reported earlier), to 90.2% for pulmonary tuberculosis and 85.7% for extra-pulmonary tuberculosis. The specificity of the test was determined by testing the sera of apparently healthy controls, and patients with other respiratory tract infections and rheumatoid arthritis. Among the apparently healthy controls, 7.3% tested positive. None of the sera from the patients with other diseases gave positive agglutination.

CONCLUSION

This simple and rapid technique could be suitable for mass screening for pulmonary and extrapulmonary tuberculosis.

Frequencies of IFN gamma- and IL-4-producing cells during Mycobacterium bovis BCG infection in two genetically susceptible mouse strains: role of alpha/beta T cells and NK1.1 cells

Frequencies of IFN gamma- and IL-4-producing spleen cells in response to Mycobacterium bovis BCG infection were determined in C57BL/6 and BALB/c mice. Both mouse strains express equal innate susceptibility to M. bovis BCG (Bcgs), but differ in their NK1.1 and T-cell activities. M. bovis BCG infection induced higher frequencies (f approximately 1/500) of antigen-induced IFN gamma-secreting spleen cells in C57BL/6 mice as compared to BALB/c mice (f approximately 1/8000). Concanavalin A stimulated almost equal numbers of IFN gamma-secreting cells in both mouse strains (f approximately 1/50). Treatment with anti-NK1.1 mAb of M. bovis BCG-infected C57BL/6 mice did not alter frequencies of IFN gamma-secreting cells. Equally low numbers of antigen-induced IL-4-producing cells (f approximately 1/3000) were determined in both C57BL/6 and BALB/c mice during M. bovis BCG infection and treatment of C57BL/6 mice with anti-NK1.1 mAb had no measurable effect on IL-4 producers. Finally, frequencies of IFN gamma-producing cells were markedly reduced (10-fold) in M. bovis BCG-infected TCR-beta-/- gene deletion mutants as compared to their heterozygous controls. Our findings verify that M. bovis BCG infection primarily induces IFN gamma-secreting alpha/beta T cells of TH1 type and show that the frequencies of these IFN gamma producers differ in the two Bcgs mouse strains C57BL/6 and BALB/c.

Antigen processing: the gateway to the immune response

The T-lymphocyte response to an antigen is governed by the source of that antigen and the way in which it is processed. Before recognition by T lymphocytes, proteins must be degraded to peptides by antigen-presenting cells. The peptides are then presented on major histocompatibility complex (MHC) molecules for recognition by the T cells. Antigens arising outside the cell (e.g., bacteria) are phagocytosed and processed by the exogenous pathway for presentation on MHC class II molecules (e.g., DR) to CD4+ cells. Antigens derived from the cytoplasm (e.g., viral proteins) are processed by the endogenous pathway for presentation by MHC class I molecules (e.g., HLA-A, -B, -C) to CD8+ cells. The response to a hapten or drug is a function of the antigen processing pathway and is determined by its chemical properties. Antigen processing also governs the T-cell response to pathogens, vaccines, and autoimmune conditions.

Antigen provoking gamma interferon production in response to Mycobacterium bovis BCG and functional difference in T-cell responses to this antigen between viable and killed BCG-immunized mice

It has been shown that gamma interferon (IFN-gamma)-producing CD4+ T cells, which are generated only by immunization with viable bacteria, exert a significant role in protective immunity against mycobacteria in mice. In this study, we have tried to determine the antigen recognized by the T cells in search of a possible protective antigen. T cells from viable Mycobacterium bovis BCG-immunized mice were stimulated with several antigens, and IFN-gamma production was measured. Purified protein derivative and viable and killed BCG lysates caused significant IFN-gamma production, and almost the same level of IFN-gamma activity was detected in both groups stimulated with viable and killed BCG lysates. However, heat shock protein (HSP) 65 and HSP 70 were not a major antigen for IFN-gamma production. The antigen provoking IFN-gamma production is localized mainly in the membrane fraction of BCG cells, and the approximate molecular size was 18 kDa. On the other hand, T cells from killed BCG-immunized mice never responded to this antigen for IFN-gamma production, whereas they could mount a delayed-type hypersensitivity response. These results showed that the antigen provoking IFN-gamma production was present in killed as well as viable BCG. In addition to the antigen presentation by antigen-presenting cells, some kinds of differentiation factor (such as monokines) that are produced only by stimulation with viable cells seemed to be necessary for the development of IFN-gamma-producing T cells.

New, sensitive and specific ELISA for the detection of neuropeptides in culture supernatants

Accurate and sensitive sandwich ELISA has been developed for the detection and identification of each of the three neuropeptides, namely, Vasoactive intestinal peptide, Somatostatin and Substance P. The neuropeptides conjugated with BSA and emulsified with Freund's adjuvant were used for immunisation of rabbits. Titres of polyclonal antibodies were checked by indirect immunofluorescence. The animals were bled when titres were high, sera separated, complement inactivated and IgG class of antibodies were purified using a protein G column. Purified IgG antibodies were used for coating the wells and for conjugation with HRPO and used for the detection of the synthetic neuropeptides in a standard solution or in the culture supernatant. The ELISA thus developed for the assay of each of the three neuropeptides had a sensitivity (0.01 ng - 12.8 ng/ml) equal to or better than that reported for these peptides by radioimmunoassay. The assay was highly specific and did not react with a panel of other neuropeptides tested. High level of sensitivity without compromising the specificity was achieved by using activated polyvinyl plates and using purified IgG from high titre rabbit anti-peptide sera. The non specific reaction was minimised by using 10,000 MW cut off amicon filtered supernatants.

An immunodominant 30-kDa antigen of a candidate anti-leprosy vaccine, Mycobacterium w, shares T and B cell determinants with M. leprae and M. tuberculosis

Earlier we reported that vaccination of leprosy patients with Mycobacterium w induces an immune response directed predominantly against low molecular weight antigens. One of these antigens, with a molecular mass of 30-kDa, was recognized by a majority of the vaccinated subjects as well as the tuberculoid leprosy patients and healthy contacts. In the present communication we report further characterization of this antigen. Immunofluorescence and Western blot studies with antibodies raised against this antigen demonstrate that it is associated with the cell surface and has homologues present in M. leprae and M. tuberculosis. Delayed-type hypersensitivity studies carried out in guinea pigs immunized with the 30-kDa antigen show that in addition to sharing B cell determinants, this immunodominant antigen of M. w also shares T cell determinants with M. leprae and M. tuberculosis.

Crosstalk between alpha/beta T cells and gamma/delta T cells in vivo: activation of alpha/beta T-cell responses after gamma/delta T-cell modulation with the monoclonal antibody GL3

Although gamma/delta T cells express numerous in vitro functions similar to alpha/beta T cells, little is known about their biological functioning in vivo. Furthermore, it is unclear whether alpha/beta T cells and gamma/delta T cells act independently or in a coordinated way. In the present study, gamma/delta T cells were modulated in vivo by i.p. injection of the anti-gamma/delta T-cell receptor (TCR) monoclonal antibody GL3. GL3 administration caused disappearance of the gamma/delta TCR in spleen and lymph node cells and the gamma/delta TCR was reexpressed after in vitro cultivation for a few days. When cultured in vitro for 4 days, in the absence of foreign antigens, spleen and lymph node alpha/beta T cells from GL3-modulated mice showed vigorous proliferative responses. CD4 T lymphocytes from GL3-modulated mice produced interleukin 2, and CD8 T cells developed into cytolytic T lymphocytes in vitro capable of lysing syngeneic and allogeneic targets. Treatment with heat-inactivated GL3 or with normal hamster immunoglobulin did not cause any of these effects. These findings suggest that the anti-gamma/delta TCR monoclonal antibody GL3 modulates gamma/delta T cells in vivo and that this modulation has profound effects on alpha/beta T-cell reactivity. Hence, the data suggest a role for gamma/delta T cells in the regulation of alpha/beta T-cell activation in vivo.

Different roles of alpha beta and gamma delta T cells in immunity against an intracellular bacterial pathogen

Several bacterial pathogens of medical importance are able to persist and replicate inside host mononuclear phagocytes. Protective immunity depends on specific T lymphocytes that induce granulomatous lesions at the sites of bacterial multiplication. Listeria monocytogenes is an intracellular pathogen that replicates inside mononuclear phagocytes and hepatocytes of mice. Invasion from the phagosomal compartment into the cytoplasmic compartment is the principal mechanism of intracellular survival. Early in infection, resistance against L. monocytogenes is mediated by polymorphonuclear phagocytes which destroy infected liver cells, followed by natural killer cells which activate macrophages by means of interferon-gamma (refs 6, 7). A specific immune response by T cells then develops which leads to sterile eradication of the microbes. T cells are also responsible for the highly effective protection in vaccinated mice against secondary infections. Although the role of alpha beta T cells has been demonstrated in these immune responses, that of gamma delta T cells is unclear. Here we use mice that selectively lack either alpha beta or gamma delta T cells as a result of targeted germ-line mutations in their T-cell receptor genes to investigate the relative roles of these T-cell populations during experimental infection with L. monocytogenes. We find that in primary listeriosis, either alpha beta or gamma delta T cells are sufficient for early protection. Resistance to secondary infection is mediated mainly by alpha beta T cells but also involves gamma delta T cells. Thus alpha beta T-cell-deficient mice can be rendered partially resistant by vaccination, and gamma delta T cells are shown to be responsible for this protective effect. In infected gamma delta T-cell-deficient mice we noticed the appearance of unusual liver lesions, indicating that gamma delta T cells have a unique regulatory role in this bacterial infection.

Cytotoxic and interferon gamma-producing activities of gamma delta T cells in the mouse intestinal epithelium are strain dependent

We have analyzed the cytolytic activity of freshly isolated intraepithelial T cells (i-IEL) from the intestines of several different mouse strains in an anti-T-cell receptor monoclonal antibody-mediated redirected lysis assay. The cytolytic activity of gamma delta i-IEL but not that of alpha beta i-IEL was strain dependent. Mouse strains could be divided into high (H), marginal (M), and null (N) strains. The anti-gamma delta T-cell receptor monoclonal antibody-induced interferon gamma production showed the same strain-dependent variability, but the proliferative responses to gamma delta T-cell receptor crosslinking did not show this variability. The N phenotype of gamma delta i-IEL was found to be dominant in (H x N)F1 mice. In radiation bone-marrow chimeras the H/N phenotype was determined by the genotype of the reconstituting bone-marrow-derived cells but was not determined by the genotype of the radioresistant host cells. Analysis of (H x N)F1 backcross animals indicated that at least two genes are involved in determination of the H/N phenotype. One of these genes is major-histocompatibility-complex linked. No difference in the use of the variable region segment of the gamma-chain or delta-chain was seen between the gamma delta i-IEL from H and N strains. Various models that might explain the strain-dependent gamma delta i-IEL phenotypes are discussed.

Cytokine production at the site of disease in human tuberculosis

Clinical and immunologic evidence suggests that tuberculous pleuritis provides a model to understand protective immune mechanisms against Mycobacterium tuberculosis. We therefore evaluated the pattern of cytokine mRNA expression and cytokine production in pleural fluid and blood of patients with tuberculous pleuritis. RNA was extracted from mononuclear cells, reverse transcribed to cDNA, and amplified by polymerase chain reaction (PCR). After normalization for T-cell cDNA, cDNA from pleural fluid cells and peripheral blood mononuclear cells (PBMC) was amplified with cytokine-specific primers. PCR product was quantified by Southern blot. For the Th1 cytokines gamma interferon (IFN-gamma) and interleukin-2 (IL-2), PCR product was greater in pleural fluid than in blood, whereas PCR product for the Th2 cytokine IL-4 was decreased in pleural fluid compared with blood. Concentrations of IFN-gamma were elevated in pleural fluid compared with serum, but IL-2, IL-4, and IL-5 were not detectable. Mean concentrations of IFN-gamma and IL-2 in supernatants of M. tuberculosis-stimulated pleural fluid cells were significantly greater than corresponding concentrations in supernatants of stimulated PBMC. In situ hybridization showed that increased IFN-gamma production by pleural fluid cells was associated with a 20- to 60-fold increase in the frequency of antigen-reactive IFN-gamma-mRNA-expressing cells. Because IL-10 can be produced by T cells and macrophages, pleural fluid cells and PBMC were normalized for beta-actin cDNA content and then amplified by PCR with IL-10-specific primers. IL-10 mRNA was greater in pleural fluid cells than in PBMC and was expressed predominantly by macrophages. IL-10 concentrations were elevated in pleural fluid versus serum. These data provide strong evidence for compartmentalization of Th1 cytokines and IL-10 at the site of disease in humans with a resistant immune response to mycobacterial infection.

In vivo depletion of CD4 and CD8 T lymphocytes impairs Mycobacterium w vaccine-induced protection against M. tuberculosis in mice

In the present study we sought to determine the relative role of CD4 and CD8 T cells in Mycobacterium w-induced protective immunity against tuberculosis of mice by in vivo depletion with specific monoclonal antibodies (mAb). Mice were immunized first with M.w, 4 weeks later treated with anti-CD4, anti-CD8 or a combination of both mAb and subsequently infected with M. tuberculosis H37Rv i.v. Numbers of colony-forming units in animals depleted of CD4 T cells, CD8 T cells or both T cell populations were significantly higher than those in control mice receiving irrelevant mAb or no mAb. Cytokine production by T cell subsets was also determined by culturing the cells remaining after in vivo depletion in the presence or absence of mycobacterial antigens. CD8 (CD4 depleted) T cells produced lower levels of interferon-gamma than CD4 (CD8 depleted) T cells. These data suggest that both CD4 and CD8 T cells participate in resistance against tuberculosis induced by vaccination with M.w.

Listeria monocytogenes-induced gamma interferon secretion by intestinal intraepithelial gamma/delta T lymphocytes

gamma/delta T cells represent a major proportion of intestinal intraepithelial lymphocytes (IEL), and it has been suggested that these IEL serve as a first immune barrier against microbial invasion and that they do so by destroying infected epithelial cells. In the present study, we confirm that both alpha/beta and gamma/delta IEL from naive mice express potent cytotoxicity and produce gamma interferon (IFN-gamma) after T-cell receptor (TCR) engagement by specific monoclonal antibodies (MAb). Intraperitoneal administration of the anti-gamma/delta TCR MAb GL3 caused downregulation of the gamma/delta TCR in IEL, and IEL from gamma/delta TCR-modulated mice failed to express cytotoxic activity and to secrete IFN-gamma after gamma/delta TCR engagement. In contrast, alpha/beta IEL from such mice were still cytolytic and secreted IFN-gamma. Mice were infected orally with virulent Listeria monocytogenes at doses which caused bacterial invasion through the intestinal epithelia. Although alpha/beta and gamma/delta IEL from these mice expressed high cytolytic activities in antibody-redirected killer assays, target cells pulsed with listerial antigens were not lysed. In contrast, IFN-gamma secretion by IEL from L. monocytogenes-infected mice was induced not only by anti-TCR MAb but also by target cells pulsed with listerial antigens, whereas irrelevant antigens, including heat shock protein 60, did not induce IFN-gamma secretion. Furthermore, the number of IFN-gamma-secreting IEL, as assessed by the enzyme-linked immunospot technique, was increased during listeriosis. gamma/delta TCR modulation by GL3 administration abrogated antigen-induced IFN-gamma secretion by IEL from infected mice. These findings suggest that L. monocytogenes induced IFN-gamma secretion by gamma/delta IEL from mice suffering from intestinal L. monocytogenes infection and invasion. Thus, the data provide evidence for a role of IFN-gamma-secreting IEL in local resistance against listeriosis and perhaps other food-borne diseases.