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Biomedical subjects

M A Bach

Publications and source records attributed to M A Bach.

At least 55 records · Page 3Linked to original sources
PubMed1989

Specific anti-M leprae PGL-I antibodies and Mitsuda reaction in the management of household contacts in New Caledonia.

Household contacts of leprosy patients have been tested for anti-phenolic glycolipid-I IgM antibodies (anti-PGL-I IgM) by an ELISA using the natural disaccharide (NDO) and natural trisaccharide (NTO) synthetic antigens. A group of healthy subjects without known exposure to Mycobacterium leprae served as controls. The percentages of positivity observed in multibacillary patients, paucibacillary patients, and household contacts were significantly higher than those of the negative controls. The absorbance values using NDO and NTO correlated well (range 0.59-0.91) when analysis of each subject group was performed. As reported here, NDO and NTO antigens seem to be equal in detecting leprosy cases; 100% of multibacillary and 21.43% of paucibacillary cases were detected as seropositive. For the screening of household contacts, NDO appears to be more sensitive and NTO more specific. There were more seropositive cases in the young age groups of household contacts, suggesting a higher rate of transmission of M. leprae infection in those age groups. Lepromin and anti-PGL-I IgG tests were also performed in contacts who were followed. The 2 paucibacillary subjects (1 borderline tuberculoid, 1 indeterminate) were Mitsuda negative. At diagnosis, their anti-PGL-I IgM levels were much higher than those of previous results; their anti-PGL-I IgG levels showed an increase in one and a decrease in the other. However, for the entire group anti-PGL-I IgM and anti-PGL-I IgG levels were positively correlated. The data reported here suggest that an increase in specific anti-M. leprae IgM levels in Mitsuda-negative household contacts could reveal the development of overt disease.

Adolescent↗
PubMed1988

Human T-cell response to myelin basic protein in multiple sclerosis patients and healthy subjects.

In order to explore the T-cell repertoire to myelin basic protein (BP) of both multiple sclerosis (MS) patients and healthy subjects (HS), we raised BP reactive T-cell lines from blood mononuclear cells of eight MS patients and five HS. These lines were triggered in vitro by human BP. When analyzing their patterns of recognition of human BP versus heterologous BP, we could observe differences between healthy subjects and MS patients. Whereas T-cell lines from healthy subjects developed a response to heterologous BP, which was in most cases equal or higher than that elicited by human BP, T-cell lines from most MS patients displayed a low response, or no response at all, to one or several of the heterologous BP tested. A low response to bovine BP was only observed in active cases, whereas decreased responses to rat and/or monkey BP were observed both during remission and during active disease. This may indicate that T-cell repertoire to BP in MS patients differs from that of healthy subjects. BP-reactive T-cell clones were obtained by limiting dilution from two healthy subject lines. Their pattern of response to heterologous BP as compared to human BP suggest that T-cells from the same individual can recognize different BP epitopes.

Animals↗
PubMed1988

Mechanisms of Mycobacterium leprae-specific T-cell deficiency in lepromatous leprosy.

Patients suffering from lepromatous leprosy fail to develop an efficient cell-mediated immunity towards Mycobacterium leprae, the causative agent. The mechanism of such a specific T-cell tolerance to the bacillus remains a key question in the pathophysiology of leprosy. Macrophages do not show any intrinsic defect in phagocytizing and killing M. leprae or in presenting antigen to helper T-cells. On the other hand, M. leprae-reactive helper T-cells do persist in lepromatous patients, but their activation appears to prevented by active suppressor mechanisms, involving both suppressor T-cells and macrophages. The target of this specific suppression could be the interleukin 2-producing T-cell subset. A better molecular definition of M. leprae antigens, both by monoclonal antibodies and T-cell clones, should open new perspectives for further analysis of the regulation of immune responses to M. leprae.

Immune Tolerance↗
PubMed1988

Non-MHC-restricted, tissue-specific T cells recognizing autologous oligodendrocytes in the normal SJL/J mouse.

The oligodendrocyte (OD), a glial cell that produces myelin in the central nervous system (CNS), represents a possible target for autoreactive T cells in autoimmune demyelinating processes. To analyze OD/T lymphocyte interactions, we sensitized in vitro SJL/J mouse spleen cells (SC) over Lewis rat OD cultures and maintained them as long-term T-cell lines in interleukin-2 (IL-2)-containing medium. The proliferative response of these lines could be elicited by syngeneic OD as well as by Lewis rat OD, but appeared to be tissue-specific since SC failed to trigger their proliferation. A T-cell clone of the CD3+, CD8+, CD4- phenotype was obtained from these lines. This clone could mount an IL-2-dependent, tissue-specific, non-major histocompatibility complex (MHC)-restricted proliferative response to OD from rat, guinea pig and various strains of mice (including syngeneic OD), but not to SC, whether resting or activated, nor to astrocytes, kidney cells or Langerhans islets. Thus, we showed that SC from normal unimmunized SJL/J mice include a so far undescribed anti-OD autoreactive T-cell population which can be grown in vitro and develop tissue-specific, non-MHC-restricted proliferative responses.

Animals↗
PubMed1988

Comparison of synthetic antigens for detecting antibodies to phenolic glycolipid I in patients with leprosy and their household contacts.

Three synthetic antigens related to the natural antigen phenolic glycolipid I (PGL-I) were compared for their efficacy in detecting leprosy when used as antigens in an enzyme-linked immunosorbent assay (ELISA) for IgM antibody to PGL-I. Absorbance values for ELISAs using the three antigens correlated well (.79 less than r less than .99) and had a high rate of agreement (89.5% less than a less than 98.4%). Of three subjects (household contacts of patients with leprosy) who later developed the disease, one with lepromatous and one with indeterminate leprosy were seropositive by ELISAs using the three antigens before the clinical onset of disease; one who developed borderline tuberculoid leprosy was seronegative. The predictive value of a positive result for the test was very low (less than 2.4%) and the predictive value for a negative result was high (greater than 99.9%) because of the low prevalence of leprosy in French Polynesia (1.78 per 1000). The high sensitivity, specificity, and efficiency of the tests using the three antigens confirmed their great value for serodiagnosis of leprosy, especially the multibacillary form; the ELISA using NTP seems to be more specific and sensitive for detecting the paucibacillary form.

Antibodies, Bacterial↗
PubMed1988

Use of anti-M. leprae phenolic glycolipid-I antibody detection for early diagnosis and prognosis of leprosy.

Untreated patients suffering from tuberculoid, lepromatous and indeterminate leprosy, their domiciliary contacts, and healthy controls, all living in Guadeloupe, West Indies, were tested by an ELISA for detecting IgM antibodies to the terminal disaccharide of the phenolic glycolipid-I antigen of Mycobacterium leprae. On most subjects, a Mitsuda test was also performed. A large majority of the tuberculoid patients and healthy subjects were Mitsuda positive. The seropositivity rate reached 44% among tuberculoid patients, and 6% among healthy subjects, with low antibody levels. Lepromatous patients were all Mitsuda negative and seropositive, with antibody production varying from low levels, as seen in tuberculoid patients, to much higher levels. Indeterminate leprosy patients included 62% Mitsuda-positive subjects and 54% seropositive subjects with a large dispersion of antibody levels. Comparing the results of the Mitsuda test to those of the ELISA by factorial analysis allowed us to define several subgroups among this population: some (25%) showed a "lepromatous-like" immune status (Mitsuda negative, seropositive); others (54%) exhibited "tuberculoid-like" profiles (Mitsuda positive without antibodies or with low antibody levels). "Lepromatous-like" cases were significantly older than "tuberculoid-like" patients. A group of subjects (17%) was Mitsuda negative and seronegative, thus displaying a true "indeterminate" immune profile, which had not been seen in other forms of the disease and had been observed in only 2 out of 51 healthy controls. A large majority of contacts was Mitsuda positive, with 33% of them being seropositive, indicating that the prevalence of M. leprae infection greatly exceeds that of overt leprosy in this population.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1987

Phenotypic composition and in vitro functional capacities of unmodified fresh cells infiltrating acutely rejected human kidney allografts.

Cell surface markers of isolated graft-infiltrating cells (GIC) were studied, and functional in vitro assays performed in 8 cases of acute irreversible rejection of human renal allografts. The GIC were mostly activated T cells (OKT11+, OKT3+, Ia+), with predominance of the cytotoxic/suppressor T cell phenotype (OKT8+). A small proportion of B cells and monocytes/macrophages were also present among these GIC. The GIC were able to proliferate with lectin of allogeneic stimulation and were strongly cytotoxic toward specific donor target cells. Within the T cell subset, OKT8+ cells displayed most of the specific cytotoxicity. Despite allograft morphology typical of cellular rejection, anti-HLA complement-dependent antibodies and antibody-dependent cell cytotoxicity were found in the eluted material from rejecting kidneys. The results of our phenotypic and functional testing of unmodified GIC (no enzyme treatment, no additional culture with or without interleukin 2), show that T cells, especially OKT8+ cells, are of paramount importance in the mechanism of this type of acute irreversible rejection of human renal allografts (i.e., to the point of allograft rupture), but other potential effector mechanisms are also present in situ.

Antigens, Surface↗
PubMed1987

Strain-dependent protective effect of adult thymectomy on murine infection by Mycobacterium lepraemurium.

C57BL/6, DBA/2, BALB/c and CBA mice were thymectomized as adults, or sham-thymectomized, and infected subcutaneously with 10(6) MLM. The number of MLM in the spleen and in the inoculated footpad was measured after 1 year of infection as well as the DTH reactions and the IgM and IgG antibody levels to MLM. Non-thymectomized mice exhibited a broad spectrum of resistance to MLM infection and of T cell mediated immunity grading from the highly resistant C57BL/6 strain to the highly susceptible CBA strain. In between, DBA/2 was found more resistant than BALB/c mice. Adult thymectomy reduced by 100 times the MLM number in the spleen of infected DBA/2 mice, without affecting that measured in the inoculated footpad, and significantly decreased DTH reaction in the same strain. No effect of adult thymectomy was observed in any other strain, except for an increase of anti MLM antibodies in BALB/c mice. These results may suggest that the medium-resistant DBA/2 strain develops after MLM infection suppressor T cells which favour MLM dissemination and are sensitive to adult.

Animals↗
PubMed1987

IL-2 receptor and HLA class II antigens on cerebrospinal fluid cells of patients with multiple sclerosis and other neurological diseases.

The presence of IL-2 receptor and HLA class II antigens as detected by monoclonal antibodies on mononuclear cells from both cerebro-spinal fluid (CSF) and peripheral blood was examined by cytofluorographic analysis in patients with multiple sclerosis (MS) and other neurological diseases. CSF as compared to blood was enriched in cells expressing IL-2 receptor and HLA class II molecules both in MS patients and in other inflammatory diseases of the central nervous system suggesting that activated T-cells concentrate within the central nervous system.

Antigens, Surface↗
PubMed1987

[Expression of interleukin 2 receptor and class II histocompatibility antigens on lymphocytes of the cerebrospinal fluid in patients with multiple sclerosis and other neurological diseases].

The presence of IL2 receptor and HLA class II antigens on mononuclear cells from both cerebrospinal fluid (CSF) and peripheral blood was examined in patients with multiple sclerosis (MS) and other neurological diseases. Cytofluorographic analysis of mononuclear cells was performed by means of indirect immunofluorescence on a flow cytometer using a linear scale. CSF as compared to blood was enriched in cells expressing IL2 receptor and HLA class II molecules both in MS patients and in other inflammatory diseases of the central nervous system. The site of activation of these cells remains however questionable.

Adult↗
PubMed1987

Influence of route of inoculation on anti-Mycobacterium lepraemurium antibody isotypes in murine leprosy.

Mice of the C57BL/6 strain were injected either subcutaneously (s.c.) in the foot pad or intravenously (i.v.) with 10(5) or 10(8) Mycobacterium lepraemurium (MLM). Anti-MLM sonicate total immunoglobulin (Ig), IgM, and IgG antibody production was followed during the course of the infection. The kinetics of appearance and the magnitude of anti-MLM antibodies were found to be related to the size and route of inoculation. The i.v. route induced earlier and higher amounts of anti-MLM antibodies than did the s.c. route. In i.v.-infected mice, a relatively predominant IgM response to MLM was observed, while a relatively higher IgG response was seen in s.c.-infected mice. IgM antibody level was found to increase sharply with the bacterial load as assessed in the spleens of mice with i.v.-disseminated infection; whereas a slow progression of both IgM and IgG levels was noted with time in s.c.-infected mice.

Animals↗
PubMed1987

Seroepidemiological study on 724 household contacts of leprosy patients in French Polynesia using disaccharide-octyl-BSA as antigen.

A seroepidemiological surveillance of a contact population was started in 1984 in French Polynesia. The ELISA test was used to measure IgM anti-ND-O-BSA in the sera. Specific antibody levels were higher in healthy Polynesians than in normal individuals living in a nonendemic country. The positive threshold of the reaction was fixed according to this background activity in healthy Polynesians. Under these conditions, 100% of the multibacillary patients were detected as seropositive as compared to 5% of the paucibacillary group. In the population of 724 household contacts tested and observed for 2 years: 93 (12.8%) were seropositive, with 8 (1.1%) showing activity equivalent to multibacillary patients (1 of these 8 individuals developed a lepromatous form of leprosy); 631 (87%) were seronegative and 3 developed a paucibacillary form of the disease (2 BT, 1 I) without any antibody increase. Among those four contacts who developed leprosy, three were related to a multibacillary index case. These data suggest that this test may be useful for the prediction of multibacillary leprosy. A long-term surveillance of this high-risk population will be able to evaluate the diagnostic and prognostic value of the serological assay.

Antibodies, Bacterial↗
PubMed1986

Bacillary growth, interleukin 2 production defect, and specific antibody secretion governed by different genetical factors in mice infected subcutaneously with Mycobacterium lepraemurium.

Different mouse strains were infected subcutaneously in the footpad with 10(7) Mycobacterium lepraemurium (MLM). At various stages of the infection, the number of acid-fast bacilli (AFB) in different organs, spleen cell interleukin 2 production, and specific IgM and IgG serum antibodies to MLM sonicate were assessed. Strains were separable into two distinct groups depending on the number of AFB recovered from the different organs, without any obvious influence of the Bcg gene. Thus C57BL/6, DBA/2, (C57BL/6 X DBA/2)F1 and C3H/Pas mice belonged to the high resistance group and DBA/1, BALB/c, and CBA strains to the low resistance group. Interleukin 2 production was depressed only in C57BL/6 and C3H/Pas mice. Anti-MLM antibody response also markedly varied according to strains, in terms of antibody titers, Ig class distribution, and species specificity, but with a different genetic pattern from that observed for MLM growth control.

Animals↗