Molecular assays for determining Mycobacterium leprae viability in tissues of experimentally infected mice.

BACKGROUND: The inability of Mycobacterium leprae to grow on axenic media has necessitated specialized techniques in order to determine viability of this organism. The purpose of this study was to develop a simple and sensitive molecular assay for determining M. leprae viability directly from infected tissues. METHODOLOGY/PRINCIPLE FINDINGS: Two M. leprae-specific quantitative reverse transcription PCR (qRT-PCR) assays based on the expression levels of esxA, encoding the ESAT-6 protein, and hsp18, encoding the heat shock 18 kDa protein, were developed and tested using infected footpad (FP) tissues of both immunocompetent and immunocompromised (athymic nu/nu) mice. In addition, the ability of these assays to detect the effects of anti-leprosy drug treatment on M. leprae viability was determined using rifampin and rifapentine, each at 10 mg/kg for 1, 5, or 20 daily doses, in the athymic nu/nu FP model. Molecular enumeration (RLEP PCR) and viability determinations (qRT-PCR) were performed via Taqman methodology on DNA and RNA, respectively, purified from ethanol-fixed FP tissue and compared with conventional enumeration (microscopic counting of acid fast bacilli) and viability assays (radiorespirometry, viability staining) which utilized bacilli freshly harvested from the contralateral FP. Both molecular and conventional assays demonstrated growth and high viability of M. leprae in nu/nu FPs over a 4 month infection period. In contrast, viability was markedly decreased by 8 weeks in immunocompetent mice. Rifapentine significantly reduced bacterial viability after 5 treatments, whereas rifampin required up to 20 treatments for the same efficacy. Neither drug was effective after a single treatment. In addition, host gene expression was monitored with the same RNA preparations. CONCLUSIONS: hsp18 and esxA qRT-PCR are sensitive molecular indicators, reliably detecting viability of M. leprae in tissues without the need for bacterial isolation or immediate processing, making these assays applicable for in vivo drug screening and promising for clinical and field applications.

Development of a mouse food pad model for detection of sub clinical leprosy.

Early diagnosis of leprosy and a multi-drug therapy (MDT) regimen will block the trajectory of nerve damage, disability and deformity that are the hallmarks of this chronic disease. However, the diagnosis of leprosy is made solely by recognition of clinical signs and symptoms, requiring special expertise. These limitations also result in the under reporting of worldwide prevalence and incidence rates for leprosy. Sorely needed is an objective laboratory test for detecting early leprosy. As the antigenic burden of M. leprae can be virtually undetectable in early clinical leprosy, cell mediated immunity and antibody responses will likely be weak. So the sensitivity of new diagnostic tests is as important as specificity. Major efforts are underway employing recombinant M. leprae antigens and synthetic peptides, to develop diagnostic assays for early leprosy infection, using in vitro T cell reactivity or serological tests. We have used the initial phase of the mouse foot pad model as an 'early' model of leprosy infection to screen T cell responses against M. leprae specific antigens and synthetic peptides. Unlike human disease in animal models we can control infection progress and monitor bacillary growth relative to time course of development of T cell response to specific M. leprae antigens. The study employed splenic T cells instead of draining lymph node T cells to model the systemic response as opposed to a local one. We found that 10(5) live M. leprae is the minimum dose required for any meaningful and consistent in vitro splenic IFN-gamma response against M. leprae antigens 3 months after foot pad inoculation. Using this model we found that several M. leprae recombinant proteins, ML0840, ML2028, ML2307, ML2346, ML2478, and ML2532, induced significant levels of IFN-gamma secretion. By controlling for variables that can be confounding factors in the sensitivity of human testing, this mouse model provides an interface between M. leprae diagnostic antigen development and the screening of these antigens in humans under field conditions.

Infection of mouse macrophages with viable Mycobacterium leprae does not induce apoptosis.

The role played by apoptosis in host response to Mycobacterium leprae is unclear. Here, we studied in vitro induction of apoptosis in mouse bone marrow-derived macrophages infected with live and irradiated M. leprae, as a function of multiplicity of infection under permissive (33 degrees C) and nonpermissive (37 degrees C) temperatures. The infected macrophages were scored for apoptosis by using DAPI (4',6-diamindino-2-phenylindole dihydrochloride) and Annexin V staining, along with activated Caspases 3 and 9 and TUNEL (terminal dUTP nick end labeling) assay. Our results show that, in contrast to uninfected cells, murine macrophages infected with live M. leprae demonstrated little, if any, apoptosis, even when macrophages had a heavy burden of live leprosy bacilli. In contrast, elevated levels of apoptosis were observed when macrophages were infected with irradiated M. leprae. The results strongly suggest that the viability and purity of the leprosy bacilli used for in vitro studies determines the extent of apoptosis observed in infected host cells.

Mycobacterium leprae actively modulates the cytokine response in naive human monocytes.

Leprosy is a chronic but treatable infectious disease caused by the intracellular pathogen Mycobacterium leprae. Host immunity to M. leprae determines the diversity of clinical manifestations seen in patients, from tuberculoid leprosy with robust production of Th1-type cytokines to lepromatous disease, characterized by elevated levels of Th2-type cytokines and a suboptimal proinflammatory response. Previous reports have indicated that M. leprae is a poor activator of macrophages and dendritic cells in vitro. To understand whether M. leprae fails to elicit an optimal Th1 immune response or actively interferes with its induction, we have examined the early interactions between M. leprae and monocytes from healthy human donors. We found that, in naïve monocytes, M. leprae induced high levels of the negative regulatory molecules MCP-1 and interleukin-1 (IL-1) receptor antagonist (IL-1Ra), while suppressing IL-6 production through phosphoinositide-3 kinase (PI3K)-dependent mechanisms. In addition, low levels of proinflammatory cytokines were observed in association with reduced activation of nuclear factor-kappaB (NF-kappaB) and delayed activation of IL-1beta-converting enzyme, ICE (caspase-1), in monocytes stimulated with M. leprae compared with Mycobacterium bovis BCG stimulation. Interestingly, although in itself a weak stimulator of cytokines, M. leprae primed the cells for increased production of tumor necrosis factor alpha and IL-10 in response to a strongly inducing secondary stimulus. Taken together, our results suggest that M. leprae plays an active role to control the release of cytokines from monocytes by providing both positive and negative regulatory signals via multiple signaling pathways involving PI3K, NF-kappaB, and caspase-1.

Lymphotoxin-alpha and TNF have essential but independent roles in the evolution of the granulomatous response in experimental leprosy.

Recent studies identified an association between genetic variants in the lymphotoxin-alpha (LTalpha) gene and leprosy. To study the influence of LTalpha on the control of experimental leprosy, both low- and high-dose Mycobacterium leprae foot pad (FP) infections were evaluated in LTalpha-deficient chimeric (cLTalpha(-/-)) and control chimeric (cB6) mice. Cellular responses to low-dose infection in cLTalpha(-/-) mice were dramatically different, with reduced accumulation of CD4(+) and CD8(+) lymphocytes and macrophages and failure to form granulomas. Growth of M. leprae was contained for 6 months, but augmented late in infection. In contrast, tumor necrosis factor knockout and tumor necrosis factor receptor 1 knockout FPs exhibited extensive inflammatory infiltration with an increase in M. leprae growth throughout infection. Following high-dose infection, cB6 FP induration peaked at 4 weeks and was maintained for 12 weeks. Induration was not sustained in cLTalpha(-/-) FPs that contained few lymphocytes and no granulomas. There was a reduction in the expression levels of inflammatory cytokines, chemokines, and chemokine receptors, including nitric oxide synthase 2, vascular cell adhesion molecule, and intercellular cell adhesion molecule. Furthermore, cLTalpha(-/-) popliteal lymph nodes contained a higher proportion of naïve CD44(lo)CD62L(hi) T cells than cB6 mice, suggestive of reduced T cell activation. Therefore, both LTalpha and tumor necrosis factor are essential for the regulation of the granuloma, but they have distinctive roles in the recruitment of lymphocytes and maintenance of the granulomatous response during chronic M. leprae infection.

Activation of complement by Mycobacterium leprae requires disruption of the bacilli.

OBJECTIVE: The immune-mediated events that precipitate erythema nodosum leprosum (ENL) are not well understood. One component may be the complexing of antibody with antigens released from infected macrophages, the activation of complement and the subsequent local inflammation. We assess here the ability of highly-purified, disrupted M. leprae, to activate complement. RESULTS: Intact and sonically-disrupted crude and alkali-purified nu/nu mouse-derived M. leprae suspensions were incubated with normal serum and a hemolytic titer (CH50) was determined as a measure of complement fixation. Crude M. leprae consumed complement, and disrupted preparations more than the intact. Purified M. leprae preparations did not consume complement unless disrupted. CONCLUSION: M. leprae, if disrupted, can activate complement. This supports a hypothesis that links released antigens with ENL, and may explain the increased probability of an occurrence of ENL following chemotherapy.

Enumeration of Mycobacterium leprae using real-time PCR.

Mycobacterium leprae is not cultivable in axenic media, and direct microscopic enumeration of the bacilli is complex, labor intensive, and suffers from limited sensitivity and specificity. We have developed a real-time PCR assay for quantifying M. leprae DNA in biological samples. Primers were identified to amplify a shared region of the multicopy repeat sequence (RLEP) specific to M. leprae and tested for sensitivity and specificity in the TaqMan format. The assay was specific for M. leprae and able to detect 10 fg of purified M. leprae DNA, or approximately 300 bacteria in infected tissues. We used the RLEP TaqMan PCR to assess the short and long-term growth results of M. leprae in foot pad tissues obtained from conventional mice, a gene knock-out mouse strain, athymic nude mice, as well as from reticuloendothelial tissues of M. leprae-infected nine-banded armadillos. We found excellent correlative results between estimates from RLEP TaqMan PCR and direct microscopic counting (combined r = 0.98). The RLEP TaqMan PCR permitted rapid analysis of batch samples with high reproducibility and is especially valuable for detection of low numbers of bacilli. Molecular enumeration is a rapid, objective and highly reproducible means to estimate the numbers of M. leprae in tissues, and application of the technique can facilitate work with this agent in many laboratories.

The role of free-living pathogenic amoeba in the transmission of leprosy: a proof of principle.

OBJECTIVES: Leprosy transmission remains poorly understood, though, prolonged skin contact and/or infection via nasal mucosa, are considered likely. Problematic in any transmission hypothesis is the fastidious nature of Mycobacterium leprae outside its host cell and the requirement for temporary survival in the environment, soil or water. Experiments were carried out to test the hypothesis that free living pathogenic amoeba might serve as host cells for M. leprae, protecting them from adverse environmental conditions. DESIGN: In this study we employed cultures of Acanthamoeba castellanii, a free-living pathogenic soil amoeba, to determine whether these protozoa can ingest M. leprae and whether the intracellular bacilli remain viable. RESULTS: More than 90% of cultured amoeba ingested M. leprae at a 20:1 multiplicity of infection while the infected amoebae thrived and multiplied normally. The ingested M. leprae were not degraded and remained viable for at least 72 hours as determined by their metabolic activity (radiorespirometry) and cell wall integrity (viability staining). M. leprae isolated from infected amoebae multiplied at the same rate as freshly harvested bacilli in the foot pads of nu/nu mice. CONCLUSIONS: These findings provide proof of principle that free-living pathogenic amoebae are capable of ingesting and supporting the viability of M. leprae expelled into the environment. Studies are underway to determine whether M. leprae-infected A. castellanii and other pathogenic amoebae may also play a role in transporting leprosy bacilli through broken skin or the nasal mucosa.

Mycobacterium leprae DNA associated with type 1 reactions in single lesion paucibacillary leprosy treated with single dose rifampin, ofloxacin, and minocycline.

Leprosy affects skin and peripheral nerves, and acute inflammatory type 1 reactions (reversal reaction) can cause neurologic impairment and disabilities. Single skin lesion paucibacillary leprosy volunteers (N = 135) recruited in three Brazilian endemic regions, treated with single-dose rifampin, ofloxacin, and minocycline (ROM), were monitored for 3 years. Poor outcome was defined as type 1 reactions with or without neuritis. IgM anti-phenolic glycolipid I, histopathology, Mitsuda test, and Mycobacterium leprae DNA polymerase chain reaction (ML-PCR) were performed at baseline. chi(2) test, Kaplan-Meir curves, and Cox proportional hazards were applied. The majority of volunteers were adults with a mean age of 30.5 +/- 15.4 years; 44.4% were ML-PCR positive. During follow-up, 14.8% of the patients had a poor clinical outcome, classified as a type 1 reaction. Older age (> or = 40 years), ML-PCR positivity, and lesion size > 5 cm were associated with increased risk. In multivariate analysis, age (> or = 40 years) and ML-PCR positivity remained baseline predictors of type 1 reaction among monolesion leprosy patients.

Antigen-specific cellular and humoral responses are induced by intradermal Mycobacterium leprae infection of the mouse ear.

Leprosy is caused by infection with Mycobacterium leprae. The immune response of leprosy patients can be highly diverse, ranging from strong cellular responses accompanied by an apparent deficit of M. leprae-specific antibodies to strong humoral responses with a deficit of cell-mediated responses. Leprosy takes many years to manifest, and this has precluded analyses of disease and immune response development in infected humans. In an attempt to better define development of the immune response during leprosy we have developed an M. leprae ear infection model. Intradermal inoculation of M. leprae into the ear supported not only infection but also the development of a chronic inflammatory response. The inflammatory response was localized, comprising a T-cell infiltration into the ear and congestion of cells in the draining lymph nodes. The development of local chronic inflammation was prevented by rifampin treatment. Importantly, and in contrast to subcutaneous M. leprae footpad infection, systemic M. leprae-specific gamma interferon and antibody responses were detected following intradermal ear infection. These results indicate the utility of intradermal ear infection for both induction and understanding of the immune response during M. leprae infection and the identification or testing of new leprosy treatments.

Emergence of an effective adaptive cell mediated immune response to Mycobacterium leprae is not impaired in reactive oxygen intermediate-deficient mice.

Cytokine-activated macrophages (MPhi) employ reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) to combat pathogens. The requirement for ROI for an effective host response to experimental leprosy using mice which have a disruption in the 91-kD subunit of the NAPDH oxidase cytochrome b (phox91-/-) was examined. Mycobacterium leprae multiplication in phox91-/- foot pads (FP) was elevated early in infection but subsequently arrested similarly to control mice within a noninvasive granuloma. Using a modified lepromin test model, a similar cellular composition in the M. leprae-induced FP granuloma in both strains with lymphocyte infiltration consisting primarily of CD4+CD44(hi)CD62L(lo) effector cells was found. Of great interest was the disparity in the T cell population between the granuloma and the draining lymph node which contained predominantly naïve CD4+CD44(lo)CD62L(hi) cells and was, therefore, not representative of the infection site. TH1 cytokines, chemokines and inducible nitric oxide synthase were comparably expressed in the FP of both strains. When infected in vitro, normal MPhi from B6 and phox91-/- mice supported bacterial viability, whereas IFNgamma-activated MPhi killed M. leprae in a RNI-dependent manner, emphasizing that ROI was dispensable. These data show that phox91-/- mice generate a strong adaptive immune response and control long-term infection with M. leprae.

Mycobacterium leprae inhibits dendritic cell activation and maturation.

Leprosy presents with a clinical spectrum of skin lesions that span from strong Th1-mediated cellular immunity and control of bacillary growth at one pole to poor Ag-specific T cell immunity with extensive bacillary load and Th2 cytokine-expressing lesions at the other. To understand how the immune response to Mycobacterium leprae is regulated, human dendritic cells (DC), potent inducers of adaptive immune responses, exposed to M. leprae, Mycobacterium tuberculosis (Mtb), and Mycobacterium bovis bacillus Calmette-Guerin (BCG) were studied for their ability to be activated and to prime T cell proliferation. In contrast with Mtb and BCG, M. leprae did not induce DC activation/maturation as measured by the expression of selected surface markers and proinflammatory cytokine production. In MLR, T cells did not proliferate in response to M. leprae-stimulated DC. Interestingly, M. leprae-exposed MLR cells secreted increased Th2 cytokines as well as similar Th1 cytokine levels as compared with Mtb- and BCG-exposed cells. Gene expression analysis revealed a reduction in levels of mRNA of DC activation and maturation markers following exposure to M. leprae. Our data suggest that M. leprae does not induce and probably suppresses in vitro DC maturation/activation, whereas Mtb and BCG are stimulatory.

Mycobacterium leprae is naturally resistant to PA-824.

Leprosy responds very slowly to the current multidrug therapy, and hence there is a need for novel drugs with potent bactericidal activity. PA-824 is a 4-nitroimidazo-oxazine that is currently undergoing phase I clinical trials for the treatment of tuberculosis. The activity of PA-824 against Mycobacterium leprae was tested and compared with that of rifampin in axenic cultures, macrophages, and two different animal models. Our results conclusively demonstrate that PA-824 has no effect on the viability of M. leprae in all three models, consistent with the lack of the nitroimidazo-oxazine-specific nitroreductase, encoded by Rv3547 in the M. leprae genome, which is essential for activation of this molecule.

DC-SIGN interacts with Mycobacterium leprae but sequence variation in this lectin is not associated with leprosy in the Pakistani population.

The C-type lectin DC-SIGN is involved in early interactions between human innate immune cells and a variety of pathogens. Here we sought to evaluate whether DC-SIGN interacts with the leprosy bacillus, Mycobacterium leprae, and whether DC-SIGN genetic variation influences the susceptibility and/or pathogenesis of the disease. A case-control study conducted in a cohort of 272 individuals revealed no association between DC-SIGN variation and leprosy. However, our results clearly show that DC-SIGN recognizes M. leprae, indicating that mycobacteria recognition by this lectin is not as narrowly restricted to the Mycobacterium tuberculosis complex as previously thought. Altogether, our results provide further elucidation of M. leprae interactions with the host innate immune cells and emphasize the importance of DC-SIGN in the early interactions between the human host and the infectious agents.

Application of a viability-staining method for Mycobacterium leprae derived from the athymic (nu/nu) mouse foot pad.

Mycobacterium leprae cannot be cultured, so ascertaining viability of the organism remains a major obstacle, impeding many avenues of investigation. This study tested a two-colour, Syto9 and propidium iodide, fluorescence assay, which scores for membrane damage in individual bacilli, to determine if a rapid direct-count viability-staining technique can be reliably applied to M. leprae. A variety of experimental conditions were employed to validate this technique. This technique was also used to correlate the viability of M. leprae with the course of athymic mouse foot pad infection to optimize the provision of viable M. leprae as a research reagent. The data show that in untreated suspensions of M. leprae there is a good correlation between the metabolic activity of leprosy bacilli and their membrane damage. Fixation of M. leprae with ethanol, paraformaldehyde and gluteraldehyde completely suppressed their metabolic activity but showed little effect on their membrane integrity. The present study also showed that the metabolic activity of M. leprae declines more than the extent of membrane damage at 37 degrees C within 72 h, but that they are not significantly affected at 33 degrees C. Irradiation at 10(4) Gy showed high numbers of dead bacilli by the staining method. The results show that the reliability of metabolic-activity data as well as viability-staining data is dependent on the method by which M. leprae is killed. This staining method helped us predict reliably that the smaller M. leprae-infected athymic mouse foot pad seen early in infection, between 4 and 5 months, yields markedly better quality leprosy bacilli than older, larger foot pad infections, as defined by their metabolic activity and membrane integrity.

Effects of purification and fluorescent staining on viability of Mycobacterium leprae.

Over the years, researchers have carried out experiments with Mycobacterium leprae obtained from either human multibacillary lesions, or infected armadillo tissues, or infected footpad tissues of conventional mice as well as athymic nu/nu mice. In general, these sources of leprosy bacilli are satisfactory for most biochemical and mouse footpad studies, but less than satisfactory for studies in cell biology and immunology where contaminating host tissues pose a serious problem. We examined the utility of a procedure for eliminating mouse footpad tissue from M. leprae suspension using sodium hydroxide solution and its subsequent effect on the viability of the organism by determining the rate of palmitic acid oxidation, bacterial membrane integrity, and growth in the mouse footpad. We found that treating M. leprae suspension, obtained from infected nu/nu mouse footpad, with 0.1N NaOH for 3 min was sufficient to remove the majority of mouse tissue without adversely affecting the viability of the organism. This is a simple and rapid method to get suspensions of nu/nu footpad-derived viable M. leprae essentially free of host tissues, which can be a research reagent for studying the host-pathogen relationship in leprosy. We also report here a method for labeling M. leprae with the fluorescent dye PKH26, without compromising on the viability of the organism. This method may be useful in intracellular trafficking studies of M. leprae or in other cell biology studies that require tracking of the bacteria using fluorescent tag. We observed the staining to be stable in vitro over considerable lengths of time and did not affect the viability of the bacteria.

IL-10 treatment of macrophages bolsters intracellular survival of Mycobacterium leprae.

In these studies, metabolically active Mycobacterium leprae were maintained for as long as 8 weeks in monolayer cultures of mouse peritoneal macrophages (MPhi). Supplemental IL-10, but not TGF-beta, bolstered, directly or indirectly, M. leprae metabolism in mouse MPhi. In the cell culture system temperature setting is extremely important and 31 to 33 degrees C incubation temperature was more permissive than 37 degrees C. Acid fast staining and transmission electron microscopy (TEM) of intracellular M. leprae revealed visible elongation of bacilli cultured under the above ideal conditions.

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.

In situ type 1 cytokine gene expression and mechanisms associated with early leprosy progression.

We explored the prognostic value of in situ cytokine patterns in 39 patients with single-skin-lesion paucibacillary leprosy before single-dose therapy, with 3 years of follow-up. Interferon (IFN)-gamma, interleukin (IL)-12, IL-10, IL-4, tumor necrosis factor (TNF)-alpha, and macrophage inflammatory protein (MIP)-1alpha mRNA was quantified in skin biopsy samples at diagnosis, and Mycobacterium leprae DNA was detected in 51.4% of cases. Type 1 immunity predominance with measurable IFN-gamma and undetectable IL-4, which is indicative of effective cell-mediated immunity, is compatible with both the reversal reactions (33.3%) and the resolution of lesions (64.1%) observed. A positive correlation between IL-12 and IFN-gamma indicated type 1 polarization via IL-12. The TNF-alpha/MIP-1alpha correlation implied the TNF-alpha induction of chemokines, which is important for granuloma formation. Positive correlations between key regulatory cytokines-IL-10 and IFN-gamma, IL-10 and IL-12, and IL-10 and TNF-alpha-suggests that there may be some level of an intralesional pro- or anti-inflammatory mechanism essential in avoiding immunopathology.

In situ type 1 cytokine gene expression and mechanism associated with early leprosy progression

We explored the prognostic value of in situ cytokine patterns in 39 patients with single-skin-lesion paucibacillary leprosy before single-dose therapy, with 3 years of follow-up. Interferon (IFN)-gamma, interleukin (IL)-12, IL-10, IL-4, tumor necrosis factor (TNF)-alpha, and macrophage inflammatory protein (MIP)-1alpha mRNA was quantified in skin biopsy samples at diagnosis, and Mycobacterium leprae DNA was detected in 51.4% of cases. Type 1 immunity predominance with measurable IFN-gamma and undetectable IL-4, which is indicative of effective cell-mediated immunity, is compatible with both the reversal reactions (33.3%) and the resolution of lesions (64.1%) observed. A positive correlation between IL-12 and IFN-gamma indicated type 1 polarization via IL-12. The TNF-alpha/MIP-1alpha correlation implied the TNF-alpha induction of chemokines, which is important for granuloma formation. Positive correlations between key regulatory cytokines-IL-10 and IFN-gamma, IL-10 and IL-12, and IL-10 and TNF-alpha-suggests that there may be some level of an intralesional pro- or anti-inflammatory mechanism essential in avoiding immunopathology.