The detection of subclinical leprosy using a monoclonal antibody based radioimmunoassay.
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Adolescent↗
Biomedical subjects
U Sengupta
Publications and source records attributed to U Sengupta.
In vitro studies on dermal granulomas of human leprosy: characterization of cells using monoclonal antibodies.
Single cell suspensions from granulomas of leprosy cases were prepared to enable an in vitro study on the characteristics of infiltrating cells. In all, biopsies from 21 untreated cases of tuberculoid leprosy and lepromatous leprosy were analyzed. The granulomas were found to contain lymphocytes and macrophages. The numbers of lymphocytes were higher in the suspensions of tuberculoid granulomas in comparison to lepromatous granulomas. A high percentage of lymphocytes from tuberculoid granulomas expressed OKT11 and Ia-like antigens, thereby indicating the presence of activated T cells. The proportion of Leu3a+ cells was greater in comparison to OKT8+ cells in these granulomas. In lepromatous granulomas, only a few positive lymphocytes expressing OKT11 or OKT8 antigens were observed. The ratio of Leu3a+:OKT8+ cells (2.79 +/- 0.61) was higher in the tuberculoid granulomas than in the lepromatous granulomas. Most macrophages from both types of granulomas expressed Ia-like antigens.
Antibodies, Monoclonal↗
Immunohistological analysis of skin reaction to My1 derived from Mycobacterium leprae.
A study was made on the in situ characteristics of dermal infiltrates in a 24-hr skin reaction using monoclonal antibodies defining T-cell subsets, Ia-like antigens, Langerhans' cells, My1, and indirect immunofluorescence. The skin reaction was induced by the mycobacterial antigen My1 derived from Mycobacterium leprae. In all, 10 biopsies were studied. The infiltrates were composed of lymphocytes and polymorphonuclear leukocytes. The predominant lymphocytes in the infiltrates were activated T lymphocytes expressing OKT11, Leu3a, OKT8, and Ia-like antigens. The ratio of Leu3a+:OKT8+ cells was 1.2 +/- 0.50. Some of the cells in the infiltrates showed the presence of My1, as seen by the staining with MLO6 monoclonal antibody. No difference was observed in the numbers of OKT6+ epidermal Langerhans' cells in the skin of My1 reaction biopsies and those of normal individuals.
Antigens, Bacterial↗
Phenolphthalein monophosphate as an alternative substrate in enzyme-linked immunosorbent assays involving alkaline phosphatase.
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Alkaline Phosphatase↗
In vitro inhibition of the activation of the human complement and coagulation systems by chloroquine.
The ability of chloroquine to inhibit the activation of the complement and coagulation systems was investigated. The activation of the classical pathway of complement by antibody coated sheep erythrocytes and aggregated IgG was blocked by chloroquine. Similarly, it prevented normal rabbit erythrocytes and zymosan from activating the the alternative pathway of complement. The activation of C3 by immune complexes of different solubilities also was inhibited by this drug. In addition, it abrogated the clotting of plasma by calcium chloride and thrombin. This effect could be reversed by the addition of excess thrombin but not of calcium chloride. It is suggested that the inhibition of these two important phlogistic mediator systems of inflammation may contribute to the anti-inflammatory property of chloroquine.
Animals↗
Reduced complement-mediated immune complex solubilization in leprosy patients.
The ability of sera from leprosy patients to solubilize immune precipitates in vitro through the complement system was studied. The solubilizing capacity of sera from patients who did not have any reactions during 2 years or more after starting chemotherapy was comparable with that of normal laboratory volunteers. On the other hand, sera from borderline tuberculoid and lepromatous leprosy patients in reaction had markedly decreased levels of solubilization. Their total and the alternative pathway haemolytic levels did not show a corresponding decrease. Although the circulating immune complexes and serum C3d of these patients came down after the subsidence of reaction, their solubilization remained consistently low during a 3 month follow-up period.
Antigen-Antibody Complex↗
Serological survey of leprosy and control subjects by a monoclonal antibody-based immunoassay.
A serological antibody competition test (SACT) using a murine anti-Mycobacterium leprae-specific monoclonal antibody (ML04) has been evaluated in 96 untreated leprosy patients and 128 control subjects. The test is based on the competitive inhibition by antibodies from human test sera of the binding of the specific 125I-ML04 murine monoclonal antibody to M. leprae soluble antigen coated microtiter plates. Along the spectrum of the disease, SACT positivity was observed in 100% of LL-BL, 87.5% of BB, and 46.7% of the TT-BT groups of patients. Moreover, 46.4% of apparently healthy household family contacts of multibacillary leprosy cases were also antibody positive. Sera from 15 contacts of paucibacillary leprosy cases as well as from 85 various nonleprosy subjects (tuberculosis, autoimmune disease, cancer, and healthy) were all found to be negative. These results satisfy the requirements of a leprosy-specific serodiagnostic test. The striking increase of antibody titer in all of the LL/BL patients indicates a potential prognostic utility of this test for the lepromatous shift of the disease. The observed positivity in a fraction of healthy leprosy contacts still requires prospective evaluation of disease incidence in a larger test sample.
Antibodies, Bacterial↗
In vitro studies on dermal granulomas of human leprosy--cellular characteristics.
Single-cell suspensions from the granulomas of leprosy cases were prepared for an in vitro study of the properties of the infiltrating cells. Biopsies from 44 untreated patients with tuberculoid and lepromatous leprosy were analyzed. The granulomas were found to contain lymphocytes and "large cells" (epithelioid cells and macrophages). The number of lymphocytes was significantly higher in the suspensions from the tuberculoid granulomas in comparison to the suspensions from the lepromatous granulomas. A high percentage of lymphocytes from the tuberculoid granulomas formed rosettes with sheep erythrocytes, and also showed the presence of esterase as dots in the cytoplasm. However, the lymphocytes did not form rosettes with EAC. Most of the "large cells" from both types of granulomas were esterase positive, exhibited peroxidase activity, and did not carry receptors for C3. A high percentage of "large cells" in the tuberculoid granulomas was nonadherent to a plastic surface, while the lepromatous granulomas contained a high proportion of adherent "large cells."
Cell Adhesion↗
Isolation and analysis of circulating immune complexes in leprosy.
Circulating immune complexes (CIC) were isolated by two antigen nonspecific methods from 60 leprosy patients belonging to borderline tuberculoid (BT) and lepromatous (LL) types with and without reactions. CIC were elevated in both BT and LL reactions. CIC from BT in reaction (BTR) were found to consist largely of IgG and C3, whereas, C-reactive protein could be found in CIC from LL reactions (LR). In addition, IgM and rheumatoid factor were demonstrated in the complexes of LR patients who had mainly arthritis. Antimycobacterial antibody was seen in the complexes of two-thirds of LR patients who had predominantly skin manifestations as part of their reaction. The relevance of these findings to the clinical manifestations of different types of reactions is discussed.
Animals↗
A serological test for leprosy based on competitive inhibition of monoclonal antibody binding to the MY2a determinant of Mycobacterium leprae.
A novel serological assay for leprosy has been devised on the basis of serum inhibition of binding of 125I-labelled ML04 monoclonal antibody to Mycobacterium leprae sonicate-coated microtitre plates. Antibodies were detected in 93% of lepromatous leprosy patients, whereas controls from the endemic area, including leprosy contacts and patients with tuberculosis, were serologically negative. The specificity and efficacy of the test may offer an advantage over previously used techniques.
Antibodies, Bacterial↗
Definition of species specific and cross-reactive antigenic determinants of Mycobacterium leprae using monoclonal antibodies.
Four soluble antigens of Mycobacterium leprae have been identified using 12 murine monoclonal antibodies. Their specificity, taxonomic distribution and molecular nature were analysed by radioimmunoassays and by immunoblotting from polyacrylamide electrophoresis gels. A protein antigen MY1 (12K) reacted with one antibody (ML06) without demonstrable cross-reactivity for any of the other 20 tested species of mycobacteria. Another four antibodies which identified antigen MY2 revealed only a marginal degree of cross-reactivity with three other species of mycobacteria. Two antigens shared by several other mycobacteria species were: MY3 represented by five protein bands (35-70K) and a subtilisin resistant molecule MY4 (40-50K) with two distinct determinants and presumably of polysaccharide nature. The described monoclonal antibodies may represent novel valuable diagnostic reagents as well as tools for the purification of antigens which could be explored towards prophylactic or therapeutic immunization against leprosy.
Antibodies, Monoclonal↗
Use of immunofluorescence technique to demonstrate complement activation in vitro by microbes.
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Animals↗
Further modification on the haemolysis method in determining bacteraemia in leprosy patients.
Bacteraemia was assessed and compared in the venous blood samples of leprosy patients by employing the existing and the modified haemolysis method respectively. The modified method was more sensitive in determining bacteraemia in these patients as evident from the finding of more number of positive cases detected by this method. A significantly higher yield of bacterial number was detected by employing the present method when compared to that obtained by earlier method.
Adolescent↗
Immunoglobulins in the urine of leprosy patients.
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Humans↗
Preliminary trial of intervention levamisole therapy in persistently bacteriologically positive lepromatous leprosy.
The intervention treatment with the immuno-adjuvant levamisole was given in 14 persistently bacteriologically positive lepromatous cases who had had adequate chemotherapy for over 5 years. There was a temporary conversion of the early lepromin reaction in a majority of the patients with a corresponding improvement in clinical and bacteriological status. However, the lepromin response was short lived. Most patients had become bacteriologically negative at the end of 1 year. No adverse effects due to levamisole therapy were encountered.
Adolescent↗
A study of continuous bacillaemia in borderline and lepromatous type of leprosy.
The present work has established beyond doubt that bacillaemia occurs practically in all cases of borderline and lepromatous leprosy. The number of bacilli in the blood is significantly high, to the tune of 4,000 bacilli per ml. Even so, it does not produce any adverse symptoms of septicaemia. Special emphasis was laid in the present study for determining the continuity or otherwise of bacillaemia. Some of the patients had continuous bacillaemia according to the criteria fixed in the present study. It was also found that the number of bacilli discharged into the blood bears no relationship with the bacillary load in the body as assessed by skin and nasal smears.
Adolescent↗
Immune status of subsided cases of tuberculoid (TT) and borderline tuberculoid (BT) leprosy.
A comparative study of lepromin reactions (early and late), M. leprae induced lymphocyte blastogenesis, per cent T Cell number in peripheral blood and immunoglobulin (IgG, IgA and IgM) levels have been made in TT-active, TT-subsided, BT-active and BT-subsided leprosy cases. No significant difference has been noted amongst these groups in the above mentioned investigations except in subsided BT cases where 9 out of 11 cases failed to evoke any late skin reaction to Dharmendra antigen. In addition, BT subsided cases also showed significantly raised levels of IgG. The significance of these findings with respect to their immunity and reinfection has been discussed.
Adolescent↗
Assessment of Dharmendra antigen. (V) attempts for purification of specific skin delayed hypersensitivity (DH) inducing antigen (S) from lepromin.
After electrophoresis (in pyrogen-free conditions) of Dharmendra antigen sonicates on agarose gel slides, the components (anionic and cationic) were eluted in pyrogen-free normal saline. On skin testing, it was found that only anionic component produced specific skin DH reactions in tuberculoid leprosy patients. The significance of the observations is discussed.
Antigens↗