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Biomedical subjects

J F Bach

Publications and source records attributed to J F Bach.

At least 631 records · Page 35Linked to original sources
PubMed1978

Peanut agglutinin. I. A new tool for studying T lymphocyte subpopulations.

Fluorescein-coupled peanut agglutinin (PNA) has been used at the single-cell level to study mouse lymphocyte subpopulations. PNA not only binds to most thymocytes, as has already been shown by other authors, but also binds to a small fraction of peripheral lymphocytes that are all T cells (theta+Ig-) or null cells (theta-Ig-). Most PNA-positive thymocytes are sensitive to in vivo corticosteroids and irradiation (450 rads) treatments. Conversely, the positive spleen cells (5% of total spleen lymphocytes) are essentially resistant to corticosteroids and irradiation. Study of PNA binding during ontogenesis shows the occurrence of PNA-positive cells in the fetal liver before thymus constitution and in the very beginning of embryonic thymus and spleen development. These data indicate that PNA is a marker of early T cell subpopulations but that there are probably several distinct subsets of PNA-positive T cells.

Animals↗
PubMed1977

[Detection of circulating immune complexes by three techniques using polyethylene glycol (author's transl)].

The search for circulating immune complexes (IC) by precipitation tests using polyethylene glycole was performed in a large series of normal (150 subjects) and 1200 pathological sera (over 800 patients). Increased precipitability of IgG and C4 was seen in a great percentage (80%) of pathological sera giving positive PEG precipitation without direct influence of IgG, IgM, C1q, C3 and C4 serum levels. The labeled C1q binding test gave similar results in 90 normal and 640 pathological sera. The C1q binding test could be replaced by the more direct and simple evaluation of the amount of C4 precipitated with IgG by 3.5% PEG. Positive results obtained in the three methods were particularly found in patients with diseases generally presumed to represent immune complexes diseases including acute glomerulonephritis, systemic lupus erythematosus, polyarteritis nodosa, subacute bacterial endocarditis, and acute or chronic hepatitis.

Antigen-Antibody Complex↗
PubMed1977

Structural study of circulating thymic factor: a peptide isolated from pig serum. I. Isolation and purification.

A circulating thymic factor (FTS) has been characterized by a bioassay based on its ability to render theta-negative rosette-forming cells theta-positive and azathioprine-sensitive. FTS was sequentially purified and finally isolated from 1000 liters of pig serum by ultrafiltration, gel filtration, and ion exchange chromatography. Its amino acid composition and apparent molecular weight estimated by Sephadex G-25 chromatography, indicate that FTS is a nonapeptide of composition lysine, aspartic acid (or asparagine), serine 2, glutamic acid (or glutamine) 2, glycine 2, and alanine.

Amino Acids↗
PubMed1977

Structural study of circulating thymic factor: a peptide isolated from pig serum. II. Amino acid sequence.

The amino acid sequence of a circulating thymic factor (FTS, facteur thymique sérique) isolated from pig serum has been established as less than Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn-OH. This sequence was obtained by Edman analysis both on the intact peptide and after tryptic digestion. The COOH-terminal residue was identified by carboxypeptidase A digestion. A synthetic peptide was prepared which showed the same biological activities as native pig circulating thymic factor, thus confirming the proposed primary structure.

Amino Acid Sequence↗
PubMed1977

[Immunological tests in the diagnosis and prognosis of disseminated lupus erythematosus, before treatment (author's transl)].

Sixty-four patients classified according to clinical manifestations, and renal pathological lesions have been submitted to a detailed immunological study before treatment. Four tests have provided significant correlations: antinative DNA antibodies (studied by a Farr test), C3, E rosette and cryoglobulins. The simultaneous considerations of these 4 parameters is however necessary in a given patient because each of them, taken separately, has no absolute value and may sometimes be clearly abnormal in patients with apparently benign outcome.

Adolescent↗
PubMed1977

Thymocyte subpopulations in young and adult mice. I. Separation by density gradient and steroid treatment.

Thymocyte subpopulations obtained after centrifugation on Ficoll density gradients have been studied in young and 6-week-old mice. Whereas the totality of the thymocytes appeared theta-positive, gradient fractionation showed the existence of a subpopulation of immunoglobulin and theta-negative lymphocytes among the lightest cells. Similar separation was obtained in both age groups in terms of the distribution of such theta-negative cells as well as of phytomitogen responses. However, cell pools with characteristics of cortical cells were less well represented in 2 to 10-day-old mice than in adult mice, indicating that post-natal thymic development is essentially associated with the appearance of cortical cells. The gradient did not however, provide a clear separation assessed on other parameters such as theta antigen, concanavalin A and phytohemagglutinin responses and steroid sensitivity. Cellular heterogeneity for a given cell density is discussed in relation to the hypothesis of two separate maturation pathways of thymocytes.

Age Factors↗
PubMed1977

Thymocyte subpopulations in young and adult mice. II. Study of steroid-resistant populations by means of a specific heteroantiserum.

Mouse steroid-resistant (Sr) cells of the thymus have been studied by means of a specific heteroantiserum. This antiserum was obtained in the rabbit after immunization with Sr thymocytes followed by absorption with high density cells isolated on a Ficoll density gradient shown to include a majority of steroid-sensitive (Ss) cells. Antigens defined by this antiserum were found on Sr thymocytes and on a significant portion of spleen and lymph node cells, but not on Ss cortical thymocytes. Cells sensitive to this antiserum appear early in the thymus (by day 15 of gestation) at the same time as Ss cells. These results suggest (a) the existence of an autonomous Sr cell line, with its own antigenic markers appearing early in ontogeny (at the same time as Ss cells), and showing wide heterogeneity in density, possibly linked to variable degrees in maturation, and (b) the medullary origin or some peripheral lymphocytes in lymph node and spleen cells that share antigenic markers with Sr thymocytes.

Age Factors↗
PubMed1977

Detection of circulating immune complexes in human sera by simplified assays with polyethylene glycol.

The search for circulating immune complexes by precipitation tests using polyethylene glycol (PEG) was performed on a series of normal and pathological sera. Various factors affecting PEG precipitation were studied. Immunoglobulins and complement factors percipitated by PEG (3.5%) were quantified and their significance was discussed in relation to serum levels. The PEG test was compared to labeled C1q binding test with a fairly good correlation. The direct evaluation of the amount of C4 precipitated with IgG by 3% PEG (C4 test) provided a simpler routine assay than the C1q binding test for detecting complement-fixing immune complexes. The direct PEG test and the C4 tests gave positive results in patients with diseases generally presumed to be associated with immune complexes including systemic lupus erythematosus, acute glomerulonephritis, bacterial sub-acute endocarditis and chronic acitve hepatitis. The demonstration of HBs antigen and antibody after acid dissociation of PEG precipitates from hepatitis B seronegative sera illustrated the fact that PEG does precipitate and thus concentrates circulating immune complexes.

Adult↗
PubMed1977

Ultrastructural study of spontaneous bone marrow rosette-forming cells.

Mouse bone marrow contains spontaneous rosette-forming cells (RFC) which include more than 70% T-cell precursors, as assessed by their transformation into theta-positive cells after incubation with thymic hormone. Such spontaneous RFC, examined in C57B1/6 mouse bone marrow by electron and scanning electron microscopy, have consistently been shown to be small, inactive mouse lymphocytes when macrophages have been eliminated by cell preincubation. These data suggest that thymic hormone target cells include small quiescent lymphocytes.

Animals↗
PubMed1977

Allogeneic lymphocyte-dependent antibodies (LDA). Specificity of Fc receptors.

Cellular receptors for the Fc fragment of IgG have been studied by the erythrocyte antibody (EA) rosette technique using either human red blood cells coated with anti-D IgG alloantibodies or pigeon red blood cells coated with aggregated IgG. Human lymphocytes were shown to form 4 to 35% of anti-D EA rosettes and 15% of E-aggregated IgG rosettes. Anti-D EA rosette values depended closely upon the amount and the source of anti-D antibodies, Ripley's type antisera giving the highest percentage of rosettes. Cell filtration through a nylon-wool column, a procedure known to remove B cells, caused a complete depletion of E-aggregated IgG rosettes and significant but only partial decrease of anti-D EA rosettes. A low but significant percentage of double rosettes were formed when anti-D-coated erythrocytes were mixed with aggregated IgG coated red blood cells or sheep red blood cells. Removal of EA-rosette-forming cells by passage on a Ficoll-Hypaque gradient K cell activity (assessed by lymphocyte-dependent antibody cytotoxicity using anti-HLA antibody-coated target cells) even when forming rosettes at low levels of erythrocyte sensitization with anti-D serum. Conversely, B cell markers (erythrocyte antibody complement rosettes or surface Ig) were only decreased at high levels of erythrocyte sensitization and remained unaffected after depletion of EA-rosette-forming cells formed at low levels of erythrocyte sensitization. These data suggest the existence of several populations of Fc receptor-bearing cells in human peripheral blood which may be differentiated according to the degree of erythrocyte IgG sensitization. Rosettes made with low concentrations of anti-D serum are mainly formed by non-B cells endowed with K cell activity, whereas those formed with high concentration of anti-D serum include B cells, monocytes, and K cells.

Adult↗
PubMed1977

Increased stimulatory capacity of spleen cells from adult thymectomized mice in mixed lymphocyte reactions.

Conflicting results have been reported concerning the effect of adult thymectomy (A-Tx) on the mixed lymphocyte reaction (MLR) response. Our purpose was to test the reverse question, namely the effect of A-Tx on the stimulatory capacity of mouse lymphocytes carrying allelic disparities at the Mls and the H-2 loci. Spleen cells from A-Tx CBA donors were found to be significantly more stimulating than cells from normal donors. That A-Tx could eliminate suppressor T cells involved in MLR regulation or in preventing back stimulation is not likely according to our data. An increment in expression or in accessibility of Mls or H-2 antigenic determinants induced by A-Tx is no more likely, since a smilar increase in lymphocyte proliferation was observed in syngeneic cultures. The most probable explanation remains that A-Tx discloses a strongly stimulatory subpopulation, perhaps acting in part nonspecifically. The hypothesis of an enrichment in B cells versus a loss of T cells is not compatible with our findings, since B-cell-enriched fractions from various origins never attained the stimulating ability disclosed by A-Tx cells. Moreover, the cell involved is theta-positive, although slightly nylon-wool-adherent, and thus shares several properties with immature T cells involved in auto-rosette formation.

Aging↗
PubMed1977

Detection of hepatitis B antigen in circulating immune complexes in acute and chronic hepatitis.

By using polyethylene glycol precipitation at low concentration (PEG test) and the radiolabeled C1q binding test, immune complexes were detected sera from acute (23/28) and chronic (28/32) hepatitis patients, hemodialyzed patients with chronic hepatitis B surface (HBs) antigenemia (7/19), and asymptomatic HBs antigen carriers (2/11). After treatment of PEG precipitates with acidic pH, heating, or proteolytic enzyme (protease), electroimmunodiffusion or radioimmunoassay revealed the presence of HBs antigen or antibody in dissociated immune complexes in sera from several acute and chronic hepatitis patients. Electron microscopy showed immune complexes of HB virus in 9 of 12 PEG precipitates obtained from PEG-test-positive sera; these 9 precipitates were from patients with acute or chronic hepatitis and the other three from chronic HBs Ag carriers. Free HB virus particles were observed after protease digestion of PEG precipitates. Neither immune complexes nor virus particles were seen in precipitates from PEG-test-negative but HBs-Ag-positive sera from chronic carriers.

Acute Disease↗