Granulomatous reaction to intradermal injection of lepromin (Mitsuda reaction) is linked to the human NRAMP1 gene in Vietnamese leprosy sibships.
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The Mitsuda test, which measures the specific immune response against intradermally injected lepromin, has a high prognostic value for susceptibility or resistance to the lepromatous form of leprosy. A sib-pair linkage analysis between the Mitsuda response and the NRAMP1 gene was done among 20 nuclear families with leprosy (totaling 118 sibs) from Ho Chi Minh City, Vietnam. All family subjects were genotyped for several intragenic and flanking NRAMP1 markers, leading to the definition of a fully informative NRAMP1 haplotype. Significant linkage was observed between NRAMP1 and Mitsuda reaction when considered either as a quantitative (P<.002) or as a categorical (P=.001) trait. Separate analyses among healthy and affected sibs showed evidence for linkage in both subsamples, indicating that linkage between the Mitsuda reaction and NRAMP1 is independent of leprosy status. These results support the view that NRAMP1 plays a regulatory role for the development of acquired antimycobacterial immune responses as determined by in vivo Mitsuda test reaction. (+info)
Specificity of the 48-hour reaction to Mitsuda antigen. Use of a soluble antigen from human and armadillo lepromin.
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Two antigens were tested and compared in relation to the 48-h Fernandez reaction. They were obtained from standard human and from standard armadillo lepromin. All the tests were negative in patients with lepromatous leprosy and highly positive in those with tuberculoid leprosy and in lepromin-positive contacts. There was total agreement in all tests done with the two types of antigen. The antigenic component has the following basic properties: it precipitates with 80% saturated ammonium sulfate; it is not destroyed by autoclaving or by treatment with 0.4% phenol; it is non-dialysable; and it is destroyed by treatment with trypsin. (+info)
Immunological studies on leprosy: separation and evaluation of the antigens of Mycobacterium leprae.
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Chromatographically separated antigens of Mycobacterium leprae were tested for their ability to elicit skin reactions in guinea-pigs sensitised with homologous and heterologous mycobacteria. Of the three antigen-positive fractions obtained, one showed specific activity and the other two cross-reactivity, as indicated by studies of hypersensitivity and passive cutaneous anaphylaxis. The fraction exhibiting specificity contained only one antigen, which was protein in nature, whereas the other two fractions contained more than one antigen and possessed both protein and polysaccharide constituents. Because the single-antigen-containing fraction showed both positive skin and PCA reactivity, the suggestion is made that this fraction may contain either an antigen with two determinants or may contain two antigens that are not easily distinguishable by immunodiffusion methods. (+info)
Detection of Mycobacterium leprae DNA by polymerase chain reaction in the blood of individuals, eight years after completion of anti-leprosy therapy.
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Thirty eight patients with indeterminate leprosy (HI), at least 4 to 6 years after discharge from multibacillary (MB) or paucibacillary (PB) schemes of anti leprosy multidrug therapy (MDT), were submitted to traditional diagnostic procedures for leprosy and to polymerase chain reaction (PCR) analysis of different clinical samples for detection of Mycobacterium leprae DNA. No significant difference was observed for any of the parameters analyzed between PB or MB schemes of treatment and no indications were found for more efficient outcome of HI using the MB scheme. Remarkably, 18 (54.5%) of the individuals were PCR positive in at least one of the samples: positivity of PCR was highest in blood samples and four individuals were PCR positive in blood and some other sample. Upon comparison of PCR results with clinical and histopathological parameters, no correlation was found between PCR-positivity and eventual relapse. This is the first report on detection of M. leprae DNA in PB patients, more than half a decade after completion of MDT, suggesting that live bacilli are present and circulating much longer than expected, although reinfection of the individuals can not be excluded. Overall, we feel that because of the high sensitivity of the assay, extreme care should be taken about association of PCR results, efficacy of treatment and disease status. (+info)
Lymphocyte transformation test in leprosy: decreased lymphocyte reactivity to Mycobacterium leprae in lepromatous leprosy, with no evidence for a generalized impairment.
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Untreated leprosy patients were examined with respect to lymphocyte transformation in vitro after stimulation with mycobacterial and other microbial antigens, allogeneic lymphocytes, or nonspecific mitogens. Methods were used to circumvent technical variability. The results were compared with those obtained in controls matched for age, sex, race, and environment. No evidence was found for a generalized impairment of lymphocyte transformation in vitro, whereas a specific defect towards Mycobacterium leprae was demonstrable in lepromatous leprosy patients. The response to M. leprae, investigated in untreated and treated leprosy patients, decreased along the leprosy spectrum. Moreover, the results of the one-way mixed lymphocyte cultures showed that lymphocytes from leprosy patients had a normal stimulator and responder capacity, when they were tested against a panel of allogeneic lymphocytes. The influence of serum factors was investigated in untreated leprosy patients in the mixed lymphocyte culture. On average, tuberculoid as well as lepromatous sera showed a low-level depressive effect, but some sera showed a stimulatory effect. Therefore, a depressive effect of serum factors cannot be considered to be a general feature of leprosy. The correlation between the Mitsuda type of lepromin skin test and the lymphocyte reactivity in vitro to M. leprae was studied, and a positive correlation was found. (+info)
A recessive major gene controls the mitsuda reaction in a region endemic for leprosy.
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BACKGROUND: Leprosy is a chronic infectious disease caused by Mycobacterium leprae. The Mitsuda reaction is a delayed granulomatous skin reaction elicited by intradermal injection of heat-killed M. leprae. Interestingly, results of the Mitsuda test are positive in the majority of individuals, even in areas not endemic for M. leprae. Like leprosy, the Mitsuda reaction is thought to be genetically controlled, but its mode of inheritance is unknown, although the role of the NRAMP1 gene has previously been reported. METHODS: We conducted a segregation analysis of quantitative Mitsuda reactivity in 168 Vietnamese nuclear families ascertained through patients with leprosy. RESULTS: We found strong evidence (P<10-9) for a major gene controlling the Mitsuda reaction independently of leprosy clinical status. Subsequent linkage analysis showed that this major gene was distinct from NRAMP1. Under the major-gene model, approximately 12% of individuals are homozygous for the recessive predisposing allele and are predicted to display high levels of Mitsuda reactivity (mean, approximately 10 mm, versus 5 mm in other individuals). CONCLUSION: We provide evidence that the Mitsuda reaction is controlled by a major gene. Our study paves the way for the identification of this gene and should provide novel insight into the mechanisms involved in granuloma formation, especially in M. leprae infection. (+info)
Infection by Mycobacterium leprae of household contacts of lepromatous leprosy patients from a post-elimination leprosy region of Colombia.
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The Leprosy Control Program of Antioquia, (post-elimination leprosy state of Colombia), had registered by 1999, 56 lepromatous leprosy patients and their household contacts (HHC). Our interest was to detect Mycobacterium leprae infection in these HHC. Clinical examination, acid-fast bacillary staining (AFB) in nasal secretions, and slit skin samples, IgM anti-PGL-I in serum and Lepromine A (Mitsuda) reactivity were tested. Two hundred forty eight HHC were studied, 49% were male. After clinical examination, two HHC were diagnosed as multi bacillary patients; 13% showed positive IgM anti-PGL-I titers; Mitsuda reaction (> or = 4 mm) was positive in 59%; AFB was negative in all samples, except in the two new patients. HHC were classified according to test results. Group 1: two new multi bacillary patients. Group 2: 15 HHC seropositive, Mitsuda-negative. Group 3: 13 HHC seropositive, Mitsuda-positive. Group 4: 130 HHC seronegative, Mitsuda-positive. Group 5: 88 HHC seronegative, Mitsuda-negative. These results are an indication that the transmission of the infection is still happening in a region considered in the post elimination phase. The two new patients represent an infection source for others contacts, and groups 2 and 3 are infected HHC that could develop the disease in future. Follow up of high risk population is necessary to achieve real elimination of leprosy. (+info)
Evidence for clonal selection of gamma/delta T cells in response to a human pathogen.
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T cells bearing gamma/delta antigen receptors comprise a resident population of intraepithelial lymphocytes in organs such as skin, gut, and lungs, where they are strategically located to contribute to the initial defense against infection. An important unsolved question about antigen-driven gamma/delta T cell responses regards the breadth of their T cell receptor (TCR) repertoire, since many specific epithelial compartments in mice display limited diversity. We have examined the diversity of TCR delta gene expression among human gamma/delta T cells from skin lesions induced by intradermal challenge with Mycobacterium leprae. We show that the vast majority of gamma/delta cells from M. leprae lesions use either V delta 1-J delta 1 or V delta 2-J delta 1 gene rearrangements and, within a given region of the lesion, display limited junctional diversity. This contrasts markedly with the extensive diversity of gamma/delta T cells from peripheral blood of these same individuals, as well as skin from normal donors. These results indicate that the gamma/delta response to M. leprae involves the selection of a limited number of clones from among a diverse repertoire, probably in response to specific mycobacterial and/or host antigens. (+info)