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Biomedical subjects

M Teodorescu

Publications and source records attributed to M Teodorescu.

At least 55 records · Page 3Linked to original sources
PubMed1981

The use of bacteria as markers of leukemic lymphocytes and for the isolation of natural killer cells.

Human lymphocyte subpopulations as well as leukemic lymphocytes can be identified and enumerated in blood smears by using bacteria that bind spontaneously to lymphocytes or by using bacteria to which antibodies are chemically coupled. The mechanism of natural binding of bacteria to lymphocytes was shown to involve a lectin on the lymphocyte surface and a carbohydrate on the bacteria. Also, we found that natural killer (NK) cells can be separated by negative selection using monolayers of bacteria. A subpopulation of T cells, identified by their binding of B. globigii, was shown to be suppressors for NK cells.

Bacteria↗
PubMed1981

Circannual variations in the B cell/T cell ratio in normal human peripheral blood.

In previous studies we have shown that B cells and subpopulations of T cells can be identified in blood smears with bacteria used as markers that bind spontaneously to lymphocytes. We have also identified Ig-bearing cells by using an Escherichia coli coated with anti-human Ig antibody. Here we determined the absolute values and the percentage of B cells and of other lymphocyte subpopulations in the peripheral blood of six normal donors every 2 mo for 1 yr. we found that the total leukocyte counts and the total number of lymphocytes remained unchanged throughout the year, whereas the percentage of B cells in the coldest month was at almost twice the level observed in summer. The percentage of cells that bind Arizona hinshawii ans Salmonella schottmülleri remained practically unchanged during the entire year. A variation was noted in the ratio between T1 and T2 cells, which also appears to be seasonally related. We speculate that hormonal factors, probably corticosteroids, are responsible for changes in the traffic of some lymphocyte subpopulations.

Adult↗
PubMed1981

The use of Salmonella schottmulleri for mapping and separation of human lymphocyte subpopulations.

Human lymphocyte subpopulations (B cells, B1, B2, T1, T2, T3, and T4 cells; our denomination) have been previously identified and isolated by bacterial adherence and functional differences between them have been demonstrated. Here we examined the binding properties of Salmonella schottmulleri to human lymphocytes in peripheral blood smears and found that it binds to more lymphocyte subpopulations, namely B, T1, T2 and T3 cells, than any bacteria previously tested. Thus, using only four bacteria: Salmonella schottmulleri, Brucella melitensis, Arizona hinshawii and Bacillus globigii we identified in blood smears B cells, two B and four T cell subpopulations. When we used gelatin-coupled monolayers of Sal. schottmulleri to isolate lymphocyte subpopulations, we showed that the nonadherent (T4) cells could be efficiently separated from the adherent cells. Furthermore, we tested the isolated subpopulations for natural killing (NK) activity and for antibody-dependent cell-mediated cytotoxicity (ADCC). Using both NK and ADCC assays, we observed a significantly higher cytotoxic activity in the nonadherent cell population than in the unseparated or adherent cell populations. Also the nonadherent cells contained most of the lymphocytes that have receptors for the Fc portion of IgG and those cells described as large granular lymphocytes. We concluded that Sal. schottmulleri is a valuable new reagent for the identification and separation of human lymphocyte subpopulations.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1981

Binding of bacteria from the genus Brucella to human B lymphocytes.

In previous studies, we have shown that various lymphocyte subpopulations bind different strains of bacteria of different genera and species. Among these bacteria was a strain of Brucella melitensis which bound to all human B lymphocytes. To determine whether the binding of B. melitensis to human B lymphocytes was strain, species, or genus characteristic, we tested the binding of B. melitensis, Brucella abortus, Brucella ovis, Brucella suis, Brucella canis and Brucella neotomae to human normal and leukemic B lymphocytes. The binding of different Brucella species to B lymphocytes was determined by single- and double-labeling experiments in which a strain of Escherichia coli, coated with anti-light chain antibodies, was used as a marker for B cells. As in previous experiments, we found that B. melitensis and antibody-coated E. coli bound to the same cells. Also, we found that all the other species of bacteria tested bound to the B lymphocytes, normal or leukemic. B. ovis and B. neotomae, which are not human pathogens, bound to fewer B lymphocytes than did the human pathogens B. abortus, B. melitensis, B. suis, and B. canis. Furthermore, we found that the quality of rosettes formed by the nonpathogenic bacteria with the lymphocytes, i.e., the number of bacteria per lymphocytes, was lower than that of pathogenic Brucella species. We conclude that all of the Brucella species tested have the ability to bind to human B lymphocytes, but that only those which are human pathogens bind firmly to all B lymphocytes and may be used as reliable markers for these cells. We also suggest that the binding of Brucella species to B lymphocytes may have some bearing on the pathogenesis of brucellosis in humans.

B-Lymphocytes↗
PubMed1981

Polyclonal B cell activator associated with alpha-2-macroglobulin in the serum of patients with rheumatoid arthritis.

We investigated whether patients with rheumatoid arthritis have a polyclonal B cell activator (PBA) in their serum by using three methods: (1) the ability of any PBA to maintain the surface Ig of rabbit or human B cells in vitro; (2) the induction of blast transformation in human B lymphocyte cultures, and (3) stimulation of nude mouse spleen cells in vitro. All three methods indicated that a PBA is present in the serum of patients with rheumatoid arthritis but not in normal individuals or in patients with arthritis in which autoimmune phenomena have not been demonstrated. The entire PBA activity in rheumatoid arthritis patient serum was found associated with the macroglobulin fraction obtained by Sephadex G-200 chromatography and was precipitated by rabbit anti-human alpha 2-macroglobulin, but not by rabbit anti-Ig antibody. When alpha 2-macroglobulin was purified from patient serum the entire PBA activity was recovered in this fraction. Normal alpha 2-macroglobulin prepared by the same procedure had no PBA activity. Thus, the existence of a PBA associated with alpha 2-macroglobulin was demonstrated in serum of patients with rheumatoid arthritis.

Animals↗
PubMed1981

An alpha2-macroglobulin associated factor produced by T lymphocytes which provides polyclonal stimulation of B lymphocytes to maintain the turnover of their surface Ig.

The supernatant of 'crowded' but not 'spread' rabbit spleen cell cultures contains a macroglobulin factor which behaves in an Ig-turnover assay as any T-independent antigen or polyclonal B-cell activator (PBA). In the supernatants of crowded rabbit lymphoid cell cultures prepared in serum free medium, the factor was found to be associated entirely with the alpha-macroglobulin (alpha M) fraction (alpha 1 + alpha 2). This alpha M was most probably actively secreted by the lymphocytes because: (i) sequential supernatants obtained in serum free medium of crowded cultures contained equal amounts of alpha M as well as equal PBA activity; (ii) the alpha M became labelled when the cells were grown in medium containing a radioactive amino acid. Macrophages were not required for the production of PBA. PBA was not produced when either crowded B or T cells were cultured alone but only when they were cultured together. Purified T cells were not triggered by any plant lectin to produce PBA. By use of anti-alpha 2M allotype antibodies and B and T cells from different rabbits, the PBA was shown to have the allotype of the T-cell donor. The PBA was associated with rabbit alpha 2M but not alpha 1M. We concluded that upon close contact, B cells stimulate T cells to produce a PBA associated with alpha 2M.

Animals↗
PubMed1981

Identification and separation by bacterial adherence of human lymphocytes that suppress natural cytotoxicity.

Human lymphocyte subpopulations (B1, B2T1, T2T3, and T4, our denomination) have been previously identified by bacterial adherence, and differences in functions (mitogen responses, specific cytotoxicity, and natural killing activity) have been associated with some of these subpopulations. The natural killing activity (NK) was located in the T4 lymphocyte subpopulation. Here we investigated the possibility that lymphocytes capable of suppressing the NK activity of the T4 cells could be identified and isolated from one of the other lymphocyte subpopulations. Freshly isolated, monocyte-depleted human peripheral blood lymphocyte (PBL) were separated into adherent and nonadherent cells after centrifugation against various bacterial monolayers. The PBL and the resulting subpopulations of PBL were tested as effector cells in a 4-hr cytotoxicity assay against the CEM lymphoblastoid cell line. The addition of viable T2 lymphocytes to either PBL or T4 lymphocytes resulted in a significant decrease in NK activity, whereas no decrease was seen when T1, T1T3, or killed T1T2 cells were added. This decrease in NK activity was not due to a simple dilution of the active NK cells, to alteration of the lymphocytes by their processing on the bacterial monolayers, or to a competition for binding to the target cells. We concluded that the T2 lymphocyte subpopulation contains the cells capable of suppressing the ability of normal human peripheral blood lymphocytes (T4 subpopulation) to perform natural killing.

Binding, Competitive↗
PubMed1981

Functional characterization of mouse lymphocyte subpopulations identified by their natural binding of bacteria. II. Identification of subpopulations of LY-1 + 2-3-, LY-1-2+3+ and LY-1+2+3+ cells and the localization of specific cytotoxic cells in a subset of LY-1-2+3+ cells .

Three T-cell subpopulations (T1, T2 and T3) can be identified by their binding of various bacteria (Mayer, Chen, Dray & Teodorescu, 1978). In this work we determined how the three subpopulations identified by their Ly-1, -2 and -3 alloantigens were distributed among the T1, T2 and T3 subpopulations. We found that the T1 subpopulation contained most of the Ly-1+2+3+ cells, that the T2 subpopulation contained some Ly-1+2-3- and some Ly-1-2+3+ cells and that the T3 subpopulation contained the remainder of the Ly-1+2+3+, Ly-1+2-3- and Ly-1-2+3+ cells. Thus the subpopulations identified by their bacterial adherence properties subdivided the three subpopulations identified by their Ly-1, -2 and -3 alloantigens. We also investigated whether the specific cytotoxic T lymphocytes were contained in the T1, T2 and/or T3 cells. We found that essentially all of the cytotoxic T lymphocytes were contained in the T3 subpopulation. Since the T3 cells contained a subpopulation of Ly-1-2+3+ cells the data indicated that essentially all of the cytotoxic T lymphocytes were contained in a subpopulation of Ly-1-2+3+ cells.

Animals↗
PubMed1980

Bacterial adherence to eucaryotic cells: isolation of lymphocyte-binding mutants.

A procedure for obtaining bacterial mutants that bind to eucaryotic cells is described. This procedure takes advantage of the ability of the mutants to obtain a required nutrient from the eucaryotic cells. We used this procedure to isolate mutants of Escherichia coli that bind to mouse lymphocytes. We show that the mutants identify some immunoglobulin-bearing lymphocytes and some non-immunoglobulin-bearing lymphocytes.

Animals↗
PubMed1980

Factors affecting the differential counting of human lymphocyte subpopulations in blood smears.

We have previously used the antibody-mediated binding of bacteria to identify Ig-bearing cells and the natural binding of bacteria to identify several lymphocyte subpopulations. By using bacteria this identification can be carried out in conventional blood smears since bacteria are small and easily distinguished from all blood elements. To develop a standardized method for identification of lymphocyte subpopulations that may become useful in clinical laboratories, we investigated here several parameters that might affect the safety and accuracy of the test, and that might simplify the procedure. We found that: (1) the rosettes formed between bacteria and lymphocytes cannot be disrupted by vigorous handling; (2) the ability fo form rosettes is a stable property of the bacterial strains; (3) for optimal results the blood sample must not be stored for more than 4 hr at 25 degrees C and the entire procedure must be performed in medium supplemented with 6% bovine serum albumin; (4) a large excess of anti-Ig antibody is required for the optimal coating of bacteria to detect Ig-bearing cells; (5) both the antibody-coated bacteria and formaldehyde-fixed bacteria can be stored at 4 degrees C or at -20 degrees C for at least 6 months; (6) the buffy coat from the blood sample can be used instead of the whole blood to reduce the time required for reading the smears; and (7) some of the pathogenic bacteria can be killed by autoclaving without modifying their binding properties. A complete and simple method which uses the bacterial adherence for the identification of lymphocyte subpopulations in blood smears is presented.

Antibodies, Anti-Idiotypic↗
PubMed1980

Isolation of human spontaneous killer lymphocytes by bacterial adherence.

Human lymphocyte subpopulations (B, T1, T2, T3, and T4 our denomination) have been identified previously by bacterial adherence and differences between them in mitogen responses and specific cytotoxic activity have been found. In this study another aspect has been investigated in order to find functions associated with these subpopulations, namely the spontaneous killing (SK) ability. Freshly isolated human peripheral blood lymphocytes (PBL) were separated into adherent and non-adherent cells following centrifugation against various bact:rial monolayers. The PBL and the resulting subpopulations of PBL were tested alone or in combination as effector cells in a 4 hr cytotoxicity assay against human lymphoblastoid cel- lines of B or T cell origin. The T3 + T4 cells or T4 cells alone showed a significantly higher SK activity against both B and T target cell lines when compared with unseparated PBL, T1 + T2, or T3 cells alone. Whe Fc portion of IgG, contain the lymphocytes responsible for SK activity and that SK cells can be purified by negative selection using bacterial adherence.

Bacteria↗
PubMed1979

Relationship between bacterial binding to lymphocytes and clinical features in chronic lymphocytic leukemia.

In previous studies we showed that spontaneous bacterial adherence can be used to identify human lymphocyte subpopulations and to demonstrate variable binding patterns in chronic lymphocytic leukemia (CLL). In this study, 10 strains of bacteria of different genera and species were used in blood smears from 24 CLL patients to determine the percentages of lymphocytes that bind bacteria. From these percentages, binding indices were calculated. The symptoms and other laboratory tests were independently recorded and the stages determined. When the two sets of data were compared, relatively low binding indices were found in symptomatic patients or in Stages III and IV; relatively high binding indices were found in asymptomatic patients or in Stages I and II. We suggest that with progression of leukemia, lymphocytes with less "lectin" recognition potential are selected and escape any control mechanism of proliferation.

Aged↗