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Biomedical subjects

U Sengupta

Publications and source records attributed to U Sengupta.

At least 55 records · Page 3Linked to original sources
PubMed1990

Detection of Mycobacterium leprae antigens in the sera of leprosy patients by sandwich immunoradiometric assay using monoclonal antibodies.

An immunological technique for demonstration of Mycobacterium leprae antigen in sera was developed by using specific as well as cross-reactive monoclonal antibodies. The sandwich immunoradiometric assay which we developed is a simple, robust assay that is sensitive to the nanogram level. Sera from 72 leprosy patients were screened for the presence of antigen by this assay. A total of 69% of untreated tuberculoid leprosy patients showed 35-kDa antigen positivity, and 45% of these patients showed anti-35-kDa antibody positivity. Consistently higher antigen positivity rates for the 35-, 12-, and 30- to 40-kDa components of M. leprae were observed in lepromatous leprosy patients than in tuberculoid leprosy patients. During the course of therapy the antigen positivity rate gradually declined, and the antigen could not be detected in any of the 15 patients with subsided cases of leprosy. As antigen is presumably in excess before the antibody response is evoked, our experimental approach for antigen detection is likely to be useful by itself or along with antibody detection for diagnosis of early leprosy.

Antibodies, Bacterial↗
PubMed1990

Detection of antibodies to 35 kD determinant of M. leprae in urine and serum of leprosy patients.

Urine and serum samples from 67 subjects comprising 55 active cases of different types of leprosy and 12 normal controls were subjected to monoclonal antibody based urine antibody competition test (UACT) and serum antibody competition test (SACT) respectively. It was possible to demonstrate M. leprae specific antibodies in the urine of 50% of the seropositive subjects. Urine antibody positivity was observed to the extent of 52% in BL/LL subjects, 50% in BB and 43% in TT/BT types of leprosy.

Antibodies, Bacterial↗
PubMed1990

Terminal complement complex in plasma of leprosy patients.

A study was carried out to find out the difference in the levels of circulating terminal complement complex between healthy volunteers and the untreated leprosy patients by using double antibody sandwich ELISA. In addition, the levels of terminal complement complex in lepromatous patients with and without reaction were also compared. None of the group showed any significant difference in the levels of circulating terminal complement complex. These findings suggest that complement may not play a direct role in tissue damage in leprosy.

Complement Activation↗
PubMed1990

Activation of complement by circulating immune complexes isolated from leprosy patients.

Circulating immune complexes isolated from different types of leprosy sera as polyethylene glycol (PEG) precipitates were found to be efficient activators of the alternative pathway of complement. PEG precipitates from BL/LL leprosy patients and those with erythema nodosum leprosum were found to activate both the classical pathway and the alternative pathway of complement efficiently, while PEG precipitates from TT/BT leprosy patients and borderline tuberculoid patients in reaction were found to active the alternative pathway of complement but not the classical pathway. No significant differences were observed between the PEG precipitates from reactional and nonreactional TT/BT and BL/LL patients in their complement activating ability.

Antigen-Antibody Complex↗
PubMed1989

CD1-positive epidermal Langerhans cells in skin reactions to autologous peripheral-blood-derived mononuclear cells in leprosy patients.

A comparison was made on the characteristics of the infiltrates, the number and distribution of CD1-positive epidermal Langerhans cells (LC) at the sites of skin reaction induced by autologous peripheral-blood-derived mononuclear cells (PBMC) in leprosy patients. Clinically and histologically, the skin reaction was well expressed in tuberculoid patients as compared to lepromatous patients, erythema nodosum leprosum (ENL) patients and contacts. The quantum of lymphocytes in the infiltrates was maximal in the tuberculoid patients and it was minimal in lepromatous and ENL patients. The number and distribution of LC in the tuberculoid patients was significantly higher in the PBMC-inoculated sites as compared to control sites over 24 h. In contrast, no difference in the number and distribution of LC was noticed in the lepromatous and ENL patients. These observations indicate that the lymphocytes of tuberculoid patients in contrast to lepromatous leprosy patients are capable of sustenance in the local micro-environments of the skin and an effective interaction may be possible between LC and PBMC.

Antigens, CD1↗
PubMed1989

Appraisal of two Mycobacterium leprae-specific serological assays for monitoring chemotherapy in lepromatous (LL/BL) leprosy patients.

Two of the Mycobacterium leprae-specific assays--a serum antibody competition (for an epitope on 35-kDa protein) test (SACT) and an enzyme-linked immunosorbent assay (ELISA) for the disaccharide epitope of phenolic glycolipid-I (PGDS)--were comparatively evaluated as tools for monitoring chemotherapy in 125 lepromatous leprosy (LL/BL) patients. An adaptation of the SACT from a radioimmunoassay (RIA) to an ELISA procedure is also described. A moderate but statistically significant correlation was observed between the assays, although SACT appeared to be the more sensitive of the two. Levels of antibodies correlated better with the bacterial index (BI) than with the duration of treatment. However, wide individual variations in antibody levels (for a specific duration of treatment or BI) were seen in treated as well as untreated patients. Anti-PGDS antibody response of the IgG type was poorer than that of the IgM type and, apparently, it did not have a bearing on either treatment duration or the BI. Further studies will be needed to clarify whether the treated patients showing a negative (or low) BI and high antibody levels were harboring hidden foci of active infection, and whether treatment could safely be terminated in patients showing low values for both BI and antibody.

Antibodies, Bacterial↗
PubMed1989

Results of a modified WHO regimen in highly bacilliferous BL/LL patients.

A regimen consisting of 600 mg of rifampin once a month, 100 mg of clofazimine on alternate days, and 100 mg of dapsone daily was used in 56 untreated, highly bacillated borderline lepromatous/lepromatous (BL/LL) patients with an average bacterial index (BI) of 4.45. Treatment was continued until skin-smear negativity. After 2 years of therapy, none of the patients had become smear negative and the average BI was 2.56. There was no growth on inoculation of skin-tissue biopsies in the normal mouse foot pad after 6 months of therapy. Bacillemia was still detectable in 11/50 patients, and significant ATP levels were detected in Mycobacterium leprae from skin-tissue biopsies in 16% of the cases. After 3 years of therapy, three patients had become smear negative. The average BI was 1.30. None of the patients had detectable bacillemia, and 5% of the cases showed detectable ATP levels in M. leprae from tissue biopsies. After 4 years of therapy, 41.7% of the patients had become smear negative. The average BI was 0.66, and no ATP was detected in any of the purified bacillary suspensions. The fall in BI was accelerated, and more patients on continued treatment became negative earlier compared to those having treatment for a limited duration, as reported by others.

Adenosine Triphosphate↗
PubMed1989

Dermatoglyphics in leprosy: (III) Creases of palm.

Palmar configurations of triradii and creases of 100 leprosy patients [50 lepromatous (BL/LL) and 50 tuberculoid (BT/LL)] were compared with those of 100 normal persons selected from families of these patients. The patterns of position of triradii were similar in controls and leprosy patients as such. But, the patterns in the two types of leprosy patients were different. As for palmar creases patterns, there was significant difference between those of controls and patients, double radial base crease occurring more often in patients. However, the differences between the two types of patients were not statistically significant.

Dermatoglyphics↗
PubMed1988

Antibodies to HIV-1 in sera from patients with mycobacterial infections.

Sera from 478 persons (348 leprosy patients, 33 tuberculosis patients, 29 healthy contacts of leprosy patients, 38 normal healthy Indians, and 30 normal healthy Europeans) were screened for anti-HIV-1 IgG antibodies by ELISA. None was positive. In addition, 132 samples (from 43 leprosy patients, 21 tuberculosis patients, 5 healthy contacts of leprosy patients, 33 normal healthy Indians, and 30 normal healthy Europeans) were also tested by Western blot assay for anti-HIV-1 IgG antibodies. Only 1 of the 63 healthy subjects expressed a prominent p17 band. One or more bands were found in 44 (leprosy patients 33/43, tuberculosis patients 7/21, and leprosy contacts 4/5) of the remaining 69 sera. Antibody to the HIV-1-specific antigen p24 was expressed by 17 of these subjects (14/43 leprosy patients, 1/21 tuberculosis patients, and 2/5 leprosy contacts), either as a single band or in combination with other bands. This raises the possibility of a common antigenic pattern between HIV-1 and mycobacteria, especially Mycobacterium leprae.

Blotting, Western↗
PubMed1988

Soluble antigen of M. leprae coupled with liposomes elicits both "early" and "late" delayed hypersensitivity skin reactions.

The soluble antigen(s) of Mycobacterium leprae was(were) coupled to liposomes and used for skin testing of leprosy patients, hoping that this mode of antigen presentation would be identical to that of integral lepromin. The liposomized antigen(s) elicited both early (24-48 hr) and late (3-4 weeks) delayed-type hypersensitivity reactions, true to the nature of lepromin, unlike the soluble antigen(s) alone which elicit(s) only the early reaction.

Antigens, Bacterial↗
PubMed1987

Immunohistologic comparison between armadillo-derived leprosin and standard lepromin skin tests in leprosy patients.

A comparison was made on the in situ immunological characteristics of dermal infiltrates of early (24-hour) and late (3-4 weeks) skin reactions in leprosy patients. The skin reactions were induced by armadillo-derived leprosin coupled to liposomes and standard Dharmendra lepromin. Most lymphocytes in the early reaction induced by both antigens were positive for Leu 4, Leu 3a, OKT8 and Ia like antigens indicating thereby the presence of activated T cells. The ratio of Leu 3a/OKT8+ cells were similar. In the late reaction elicited by both antigens, the lymphocytes in the granulomas were predominantly activated T lymphocytes expressing Leu 4, Leu 3a, OKT8 and Ia like antigens. Leu 3a+ cells were scattered diffusely amidst the epithelioid cells. In contrast, the OKT8+ cells were present mainly as 'a ring' in the periphery of the granuloma. A similar ratio of Leu 3a+/OKT8+ cells was observed in these granulomas. Macrophages in the granulomas expressed Ia like antigens. These observations indicate that the immunological characteristics of dermal infiltrates in the skin reaction induced by armadillo-derived leprosin coupled to liposomes and standard Dharmendra lepromin appear to be identical.

Animals↗
PubMed1987

Comparative study of immunizing and delayed hypersensitivity eliciting antigens of Mycobacterium leprae, M. tuberculosis, M. vaccae, and M. bovis (BCG).

A variety of mycobacterial antigens have been associated with the delayed-type hypersensitivity (DTH) reactions in human beings and animals. An attempt has been made in the present study to identify the major antigen fractions of Mycobacterium leprae and M. tuberculosis responsible for the elicitation of DTH and to evaluate their specificity by a comparison with the antigens of two closely related mycobacteria, BCG and M. vaccae. Guinea pigs and mice were sensitized with native or heat-killed M. leprae, M. tuberculosis, M. vaccae, and BCG. Four fractions each of the latter three mycobacteria, obtained by preparatory polyacrylamide slab gel electrophoresis, were used for elicitation of DTH. Three fractions of M. leprae (MY1, MY2, and MLSE) were obtained by affinity chromatography using monoclonal antibodies. Heat-killed M. leprae and M. vaccae proved to be better sensitizers for DTH compared to their native counterparts, whereas there were no significant differences between the efficacies of autoclaved and unautoclaved M. tuberculosis or BCG. The best DTH responses were recorded with a 16-24 kD fraction of M. tuberculosis, a 20-27 kD fraction of BCG, and MLSE of M. leprae. The purified molecules of M. leprae, MY1 (12 kD) and MY2 (35 kD), did not elicit a DTH reaction. Although none of the fractions of M. tuberculosis or BCG exhibited species specificity, fraction II (15-24 kD) of M. vaccae and MLSE might be comprised of species-specific determinants.

Animals↗
PubMed1987

Suppression of delayed hypersensitivity skin reactions to tuberculin by M. leprae antigens in patients with lepromatous and tuberculoid leprosy.

Delayed hypersensitivity skin reactions to tuberculin when injected alone or in mixture with antigens of M. leprae were examined in leprosy patients and in healthy controls. The tuberculin reaction was significantly inhibited in more than one half of both LL and BT patients by the soluble extract of M. leprae (leprosin), the leprosin derived 12 kD protein or leprosin depleted of the 12 kD antigen. However, suppression was not found in healthy controls from a leprosy endemic region. These results suggest that multiple M. leprae-specific antigens have an immunoregulatory function. Since suppression was demonstrable not only in LL (leprosin-anergic), but also in BT (leprosin-responder) patients it is of interest that the 'mixed' skin test can discriminate the immune status of at least certain BT patients from that of the infected but self-healing healthy controls. Corollary lymphocyte cultures failed to show any suppression by leprosing of the lymphoproliferative responses to tuberculin.

Antigens, Bacterial↗
PubMed1986

Detection of mycobacterial antigens in leprosy serum immune complex.

The antigens from immune complexes of sera from patients with mycobacterial diseases were released by sodium dodecyl sulfate. The antigenic activity of the released proteins was tested by agar gel diffusion and immunoelectrophoresis. This simple method provided direct evidence for the presence of mycobacterial antigens in the immune complexes of sera from patients with leprosy and tuberculosis.

Antigen-Antibody Complex↗