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D T Yu

Publications and source records attributed to D T Yu.

48 records · Page 3Linked to original sources
PubMed1977

Human monocyte-lymphocyte interaction: a new technique.

A rosette-type assay of the physical interaction between lymphocytes and monocytes after treatment with neuraminidase-galactose oxidase (NGAO) is reported. Monocyte-lymphocyte (ML) rosette formation and subsequent lymphocyte proliferation occurred when either lymphocytes or homologous monocytes were treated with NGAO and cultured together. Maximal ML rosette formation took place at 37 degrees C 4 hr after culture in media containing 10% serum at lymphocyte to monocyte ratios of 10:1 to 20:1. The percentage of rosette formation correlated with the extent of thymidine incorporation when increasing concentrations of NGAO were used. When NGAO-treated monocytes were added to untreated T and non-T lymphocytes, they bound preferentially to T lymphocytes and induced proliferation only in the T subpopulation. These results indicate that the ML rosette assay measures a highly specific monocyte-lymphocyte physical interaction after a mitogenic stimulus which is an early event in lymphocyte activation since it reflects the degree of subsequent lymphocyte proliferation.

Cell Separation↗
PubMed1976

Lymphocyte subpopulations: analysis of T-cell rosette characters.

The data indicated that 2 populations of thymocytes existed: immature and mature types, identifiable by their rosette characters. The immature type was capable of changing spontaneously to the mature type, but was partially suppressed in vivo by the high concentration of thymic hormone present in the intrathymic environment. The mature types of thymocytes emigrated to the peripheral organ, accounting for their high percentage of small rosettes. Alternately, cells of peripheral organs might have originated from the immature type in the thymus. Once emigrated and exposed to a lower concentration of thymic hormone, they changed into the mature pattern. The fact that lymph node rosettes were less affected by culture in vitro indicated that once cells have changed to the mature pattern they have less ground for further differentiation.

Animals↗
PubMed1976

Human lymphocyte subpopulations: the effect of pregnancy.

Peripheral blood lymphocytes from pregnant and nonpregnant females were studied for the presence of the following surface receptors: (i) Receptor for heat-aggregated human IgG (AggIgG); (ii) Receptor(s) for complement components; (iii) Receptor for sheep red blood cells (SRBC). Absolute numbers of lymphocytes with receptors for complement and those with receptors for SRBC were present in equal numbers in both groups. However, in the pregnant females there was a significantly lower number of lymphocytes with receptors for AggIgG. It is hypothesized that some of the immunological changes which occur during pregnancy may be mediated partly through changes in the total numbers of certain lymphocyte subpopulations.

B-Lymphocytes↗
PubMed1976

Human lymphocyte subpopulations effect of epinephrine.

The effect of administration of 0-2 mg of epinephrine (Parke-Davis) on circulatory lymphocytes was investigated in fifteen normal subjects. Blood samples were taken prior to, 10 and 20 min after, subcutaneous injections. Thymus-derived (T) cells were assayed by sheep red blood cell rosettes, bone marrow-derived (B) cells by their complement receptors and immunofluorescent detection of Fc receptors plus surface immunoglobulins. Their percentages prior to injections were 72-2 +/- 1-4, 13-8 +/- 1-1, and 20-3 +/- 1-3. Ten minutes after injections, the absolute concentrations of these cells increased to 164 +/- 14%, 326 +/- 57%, and 272 +/- 45% respectively of the values prior to injection (averages +/- standard errors). Further, when cells with receptors for both sheep red blood cells and complement were assayed by simultaneous rosette technique, they increased from 2-5 +/- 0-4% to 10-5 +/- 1-3% of the lymphocytes. Such changes were also observed in three subjects who had undergone splenectomy more than 2 years previously, but not in four subjects receiving injections of saline instead of epinephrine.

Adult↗
PubMed1976

Generation of activated lymphocytes. Analysis of giant SRBC rosettes.

Giant SRBC rosette-forming cells were detected in samples of mitogen-stimulated human peripheral blood lymphocytes. When the concentrations of mitogens were varied, the amount of [3H]TdR incorporated by the lymphocytes also varied. In general, the higher the amount of [3H]TdR incorporated, the higher were the percentages of giant rosettes. Hence the percentages of rosettes constituted a reliable index of mitogenic responses. Lymphocytes were stimulated by mitogens and cultured in the presence of cardiac glycosides or inhibitors of the synthesis of DNA, RNA or protein. The generation of giant SRBC rosette-forming cells was found to be dependent on RNA and protein synthesis and the integrity of membrane Na+ K+ ATPase, but not on DNA synthesis.

Adenosine Triphosphatases↗
PubMed1976

Human lymphocyte subpopulations: giant SRBC rosettes.

Human thymus-derived lymphocytes have the ability to form rosettes with sheep red blood cells (SRBC) in vitro. In the investigation of rosettes of peripheral blood lymphocytes of 10 normal subjects, the number of SRBC adhering to the lymphocyte in each of 100 rosettes was assessed. The percentage of rosettes with SRBC greater than or equal to 36 per rosette was only 1.2 +/- 0.5. These were defined as giant SRBC rosettes. Peripheral blood lymphocytes were stimulated in vitro by four mitogens: sodium periodate, neuraminidase plus galactose oxidase, pokeweed mitogen, and concanavalin A. The lymphocytes were then cultured at 37 degrees C. The giant rosette-forming lymphocytes became significantly increased 4 to 24 hr after stimulation, prior to the appearance of lymphoblasts or increased incorporation of tritiated thymidine. The giant rosettes were not caused by the hemagglutinating properties of pokeweed mitogen and concanavalin A that were adsorbed on the lymphocyte surfaces. This was shown by the fact that, on removal of the receptors by trypsinization, they were regenerated on culture in vitro in the absence of the mitogens. It was concluded that giant SRBC rosettes constituted a marker for some of the activated lymphocytes. Their appearance was independent of the increase in size of the cells or of DNA synthesis. These receptors were intrinsic to lymphocytes and not caused by mitogens adsorbed on their surfaces.

Animals↗
PubMed1975

Human lymphocyte subpopulation: early and late rosettes.

In the process of forming SRBC rosettes of human lymphocytes, two types were distinguished, the early and late rosettes. The former appeared immediately whereas the latter required further incubation at 4degreesC. In this study, the two types of cells were separated by gradient centrifugation and studied separately. It was found that the proportion of caps in the late rosettes was much greater than in the early ones. Treatment of the former by trypsin, AET, and neuraminidase decreased this proportion so that it resembled the late one. It was postulated that some of the differences in the early and late RFC lie in the differences in the content of membrane sulphydryl and sialic acid groups and distribution of SRBC receptors.

Animals↗
PubMed1975

Effect of polycations and polyanions on behavior of sheep red blood cell rosettes of human lymphocytes.

The role of cell surface charges in the behavior of sheep red blood cells (SRBC) rosettes with human lymphocytes was investigated by using various polycations and polyanions. Polycations (DEAE-dextran, polybrene, poly-L-lysine, spermadine) at appropriate concentrations (1) invariably increased the proportions of early rosettes. This was so irrespective of whether it was the SRBC or the lymphocytes that were being treated with the reagents. (2) The rosettes so formed also consisted of a greater number of red blood cells per rosette (3). On incubating the rosettes at 37 degrees C, they dissociated by capping. The rates of dissociation and capping were retarded by polycation treatment. (4) The resistance to rosette disruption was increased. These properties were very similar to those observed on cells treated with neuraminidase. Treatment of cells with the polyanions heparin and dextran sulfate induced the opposite effects: reduced the number of rosettes and increased the rate of dissociation, and decreased the resistance of rosettes to disruption. It was concluded that alterations of cell surface charges could drastically influence SRBC-lymphocyte interactions. To investigate whether rosette inhibitors could do so by altering cell surface charges, cell were treated with anti-lymphocytic sera, 2,4-dinitrophenol and sodium azide. All three agents inhibited rosette formation. Whereas DEAE-dextran could partially reverse the inhibition by the first two agents, it failed to do so with the third. This suggested that the first two may have inhibited rosette formation by altering the surface charges.

Animals↗
PubMedDate not supplied

Lymphocyte involvement in rheumatoid arthritis. Studies during thoracic duct drainage.

Grip strength, ring size, duration of morning stiffness, and the number of tender joints improved significantly in 9 patients with severe rheumatoid arthritis during prolonged continuous removal of thoracic duct lymphocytes through a surgical fistula. There was no improvement in 4 subjects in whom surgery failed to establish satisfactory lymph drainage. Reinfusion of unlabeled or 51Cr-labeled autologous lymphocytes resulted in transient exacerbation of disease activity in 3 subjects. Following reinfusion, some 51Cr-labeled lymphocytes could be found in the inflamed synovium and synovial fluid by autoradiography, and radioactivity was detected over the joints by surface counting of gamma radiation. Active rheumatoid arthritis recurred in all subjects at variable intervals after cessation of lymph drainage. These findings are compatible with the hypothesis that some of the lymphocytes in the thoracic duct lymph are essential for the continued activity of the inflammation associated with rheumatoid arthritis.

Adult↗
PubMedDate not supplied

Epitope analysis of an HLA-B27-derived synthetic peptide: a possible approach to analyzing HLA class I antigens.

A monoclonal antibody, F3H7, was generated by immunizing mice with a synthetic peptide corresponding to residues 63-84 of the B*2705 allele of the HLA-B27 antigens. The reactive epitope and the contact residues on the peptide were localized by ELISA using a large panel of overlapping peptides as well as peptides with substituted amino acids. Residues corresponding to R75, D77 and L78 on the HLA-B27 protein appeared to be critical. The clarity of these results indicate that this is a potentially useful approach to the study of HLA class I epitopes.

Alleles↗
PubMedDate not supplied

A monoclonal anti-HLA-B27 antibody which is reactive with a linear sequence of the HLA-B27 protein is useful for the study of molecular mimicry.

In the search for cross-reactivity between bacteria and HLA-B27, three groups of investigators have identified several bacterial envelope proteins which are reactive with the monoclonal anti-HLA-B27 antibodies B27.M1 and B27.M2. Since these two antibodies react poorly with HLA-B27-derived synthetic peptides, it is not possible to locate the reactive epitopes on the HLA-B27 using synthetic peptides. Here, we introduce Ye-2, a monoclonal anti-HLA-B27 antibody which, unlike B27.M1 and B27.M2, is reactive with a synthetic peptide derived from residues 63-84 of HLA-B27.1. Analysis with a cross-reactive peptide derived from residues 226-244 of bovine carbonic anhydrase suggests that only a few of the amino acid residues in the HLA-B27-derived peptide are responsible for the reactivity. This antibody should be a useful adjunct in a preliminary assessment of whether a bacterial protein mimics HLA-B27 in primary structure.

Amino Acid Sequence↗