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B R Smith

Publications and source records attributed to B R Smith.

At least 217 records · Page 12Linked to original sources
PubMed1987

CTL adhesion and antigen recognition are discrete steps in the human CTL-target cell interaction.

Th initial step in cytolytic T lymphocyte (CTL)-mediated cytolysis involves target cell adhesion and antigen recognition. To investigate these initial events in the CTL-target interaction, we used HLA-A2- and HLA-B7-specific human CTL clones and HLA-typed B lymphoblastoid target cells. By using two different adhesion assays, we demonstrated antigen nonspecific CTL-target cell adhesion. To more precisely define the contribution of the antigen-specific receptor to CTL-target cell adhesion, we used the HLA-A2, HLA-B7, and mock transfected RD target cells. Consistent with the results when using B lymphoblastoid target cells, the CTL clones demonstrated equivalent adhesions to the RD target cells whether or not they expressed HLA-A2 or HLA-B7. These results suggested that CTL-target cell adhesion occurred independent of the T cell receptor. By using the calcium-sensitive dye Indo-1 and flow cytometry, we assessed CTL-target cell adhesion and CTL activation. Simultaneous measurement of adhesion and intracellular free calcium demonstrated that CTL-target cell adhesion alone did not activate CTL clones. Both CTL-target cell adhesion and the presence of the appropriate HLA target molecule were necessary for the efficient activation of human CTL. MAb inhibition studies indicated that antigen nonspecific adhesion is largely regulated by the LFA-1, CD2 (LFA-2/T11), and LFA-3 cell surface molecules. These antigen nonspecific cell-cell interaction molecules appear to play an important role in facilitating antigen recognition and subsequent target cell lysis.

Antibodies, Monoclonal↗
PubMed1987

Structure-activity analysis of microsomal antigen/thyroid peroxidase.

The interaction between thyroid microsomal autoantibodies and thyroid microsomal antigen/thyroid peroxidase (TPO) has been studied using both intact antigen preparations and their water-soluble trypsin fragments. In an analysis of sera from 30 patients with Graves' or Hashimoto's diseases, microsomal antibodies showed similar reactivity towards trypsin fragments (with TPO activity) and intact detergent (sodium deoxycholate, DOC)-solubilized human microsomal antigen preparations (r = 0.96). This raised the possibility that both the peroxidase-active site and the major autoantigenic site(s) of microsomal antigen were present on the same trypsin fragments. Studies with porcine TPO showed that only a few sera contained microsomal antibodies which cross-reacted strongly with the porcine preparations. Further analysis was carried out by immunoprecipitation of 125I-labelled microsomal antigen followed by SDS-PAGE and autoradiography. These studies suggest that intact human microsomal antigen (a single-chain protein with Mr = 110,000) contains an intrachain loop of amino acids formed by a disulphide bridge. Trypsin treatment cleaves the antigen close to its transmembrane section and releases a water-soluble fragment (Mr = 100,000), containing the intact disulphide-linked loop of amino acids. Further trypsin action causes cleavage of the peptide bonds within the loop in some preparations. Consequently, three major water-soluble trypsin fragments (Mr = 100,000, 73,000 and 68,000) are formed all of which contain an intact disulphide bridge and have microsomal antibody binding activities. The integrity of the disulphide bridge in intact antigen/TPO preparations and their trypsin fragments is essential for autoantibody binding activity.

Animals↗
PubMed1987

B lymphocyte reconstitution after human bone marrow transplantation. Leu-1 antigen defines a distinct population of B lymphocytes.

Differences in the expression of Leu-1 (CD5) define two populations of recovering B cells after human marrow transplantation, Leu-1+ and Leu-1- B cells. The Leu-1+ B cells were polyclonal, of donor origin, and did not express detectable interleukin 2 receptor. Leu-1+ B cells generally appeared 2-4 wk after marrow grafting and often preceded the recovery of Leu-1- B cells. Acute and chronic graft vs. host disease (GvHD) resulted in the recovery of significantly fewer Leu-1+ B cells, whereas Leu-1- B cells were only decreased in acute GvHD. Multivariate analysis showed no significant effect of age, disease, prednisone or azathioprine, or ex vivo treatment of the marrow with anti-Leu-1 and complement on recovery of Leu-1+ and Leu-1- B cells, independent of the effects of GvHD. Leu-1+ B cells are a major lymphocyte population posttransplant. They may reflect a stage of differentiation of normal B cells or a separate B cell lineage.

Antibody Formation↗
PubMed1987

Squamous cell carcinoma on the dorsum of the tongue arising in a long-standing lesion of erosive lichen planus.

Considerable controversy exists regarding the malignant potential of lichen planus. Although a number of cases of malignant transformation have been reported, many have lacked adequate documentation. A histologically well-documented case of squamous cell carcinoma on the dorsum of the tongue arising in a long-standing lesion of erosive lichen planus is presented.

Carcinoma, Squamous Cell↗
PubMed1987

The thyroid microenvironment in autoimmune thyroid disease: effects of TSH and lymphokines on thyroid lymphocytes and thyroid cells.

Thyroid lymphocytes synthesize thyroid autoantibodies in close proximity to thyroid cells and consequently soluble mediators such as TSH and interleukins (IL) 1 and 2 may have unforeseen effects on lymphocytes and thyrocytes, respectively. Investigations of thyroid autoantibody synthesis by thyroid lymphocytes in vitro showed that TSH did not affect microsomal (Mic) antibody production, but thyroglobulin (Tg) antibody synthesis was decreased, probably as a result of complexing between Tg antibody and Tg secreted by small numbers of thyrocytes in the cell suspension. IL-1 and IL-2 partially mimicked the inhibitory effects on spontaneous autoantibody synthesis induced by Pokeweed mitogen (PWM) in cultures of thyroid lymphocytes. This inhibition may require a number of soluble mediators released by T cells in response to the mitogen; however, depletion studies indicated that the cell type responsible for PWM inhibition is unlikely to be a suppressor T cell and may be an NK cell. IL-1 and IL-2 had little effect on the viability of thyrocyte monolayers in an 18 h assay, but antibody dependent cells cytotoxicity (ADCC) using blood lymphocytes and thyroid autoantibody positive sera was demonstrated; further, the cytotoxicity appeared to be due to Mic antibodies. It is possible that IL-1 and/or IL-2 (as well as other cytokines) may affect thyroid cells after longer periods of exposure, either by altering them functionally or by direct damage. However, assuming that NK cells are present in sufficient numbers in the gland, ADCC could play a major role in the development of hypothyroidism in Hashimoto's disease.

Cells, Cultured↗
PubMed1987

Retarded recovery of functional T cell frequencies in T cell-depleted bone marrow transplant recipients.

We have studied the effect of removing donor T cells by treatment with the monoclonal antibody Leu-1 and complement before marrow transplantation on the regeneration of functionally competent T lymphocytes in the blood at selected times after transplant. Using sensitive limiting-dilution methods that allow us to enumerate helper, cytotoxic, and proliferating T lymphocyte precursors, we report that regeneration of a functional T cell compartment is more severely impaired for the first 180 days after transplantation in those patients given T cell-depleted bone marrow than in recipients of untreated marrow. After this first 6 months, however, patients given T cell-depleted bone marrow had blood T cell frequencies comparable to those observed in patients given untreated marrow. Diminished frequencies of reactive T cells in recipients of depleted marrow could leave them more susceptible to infection or to the recurrence of neoplastic cells.

Bone Marrow Cells↗
PubMed1987

T cell regulation of thyroglobulin autoantibody IgG subclasses in Hashimoto's thyroiditis.

Microsomal and thyroglobulin (Tg) antibodies in patients with autoimmune thyroid disease are usually predominantly of subclasses IgG1 and/or IgG4 and the distribution pattern is characteristic for the serum of an individual. We have studied the role of T cells in synthesis of total IgG and Tg antibody IgG subclasses (measured by ELISA) in cultures of peripheral blood lymphocytes (PBL) from Hashimoto patients. Unfractionated PBL incubated with the T dependent activator pokeweed mitogen (PWM) synthesized IgG of all four IgG subclasses in the proportions 69% IgG1, 20% IgG2, 8% IgG3 and 3% IgG4; these values are similar to the proportions of the subclasses in serum. In contrast, the IgG subclass of Tg antibody was predominantly IgG1 in one patient, approximately equal proportions of IgG1 and IgG4 in four patients, and almost completely restricted to IgG4 in one patient; these patterns were similar to the subclass distribution of the autoantibodies in the individual patients' serum. B cells incubated alone secreted little Tg antibody but the response could be restored to the original levels and proportions of IgG1 and/or IgG4 Tg antibody by the addition of T cells either from the same individual or from another donor. Further, removal of suppressor T cells had little effect on the proportions of IgG1 and IgG4 Tg antibody although the total amounts of Tg antibody of both subclasses were sometimes increased. Our studies indicate that T cells are required in this in vitro system to elicit Tg antibody synthesis and to control the magnitude of the antibody response. However, the characteristic IgG subclass distribution of Tg antibody in an individual is determined at the level of the B cell.

Autoantibodies↗
PubMed1987

Efficacy and safety of aztreonam in the treatment of serious gram-negative bacterial infections.

Aztreonam was used in the initial treatment of infection of the urinary tract (23 cases), respiratory tract (17 cases), skin and soft tissue (12 cases), abdominal cavity (three cases), endocarditis (two cases), septicemia (eight cases), and osteomyelitis (two cases). In 26 of 60 evaluable infectious episodes, aztreonam was used alone. Clinical cure was observed in 35 of 60, improvement in 24 of 60, and failure in one of 60 cases. Ten patients developed subsequent superinfection. Aztreonam was well tolerated, although one case of exfoliative dermatitis and one of pseudomembranous colitis occurred. However, these cases were complicated by proximal administration of other antibiotics.

Adult↗
PubMed1986

Long-lasting deficit of functional T cell precursors in human bone marrow transplant recipients revealed by limiting dilution methods.

We have applied limiting dilution methods suitable for the estimation of mitogen-reactive helper (pHTL) and cytotoxic (pCTL) T cell frequencies to the analysis of immune function in patients 1 mo to 6 yr after allogeneic bone marrow transplantation (BMT). Although the majority of these patients have regained normal levels of Leu-3+ (helper) and Leu-2+ (killer/suppressor) cells by 6 to 12 mo after BMT as assessed by cytofluorimetry, the fraction of these cells that can function in limiting dilution cultures is substantially below normal levels in nearly all patients. Although some BMT patients eventually recover normal frequencies of pCTL and pHTL, values typically remain greatly depressed even in patients transplanted as many as 4 to 6 yr previously. In contrast, recovery of precursors able to proliferate (without expressing either helper or cytotoxic function) in response to phytohemagglutinin (PHA) and interleukin 2 occurs in many patients by 1 yr after transplant. In spite of the decreased frequency of functional precursor cells found after BMT, each precursor is capable of giving rise to the same amount of function at limiting dilutions as that produced by cells from normal controls. In many BMT patients, proliferation in conventional PHA-stimulated cultures returns to near-normal levels even though precursor frequencies remain low. The limiting dilution method is sensitive to residual immune dysfunction in BMT recipients not easily quantitated by other, more conventional techniques.

Adolescent↗
PubMed1986

Thyrotropin cross-links to the thyrotropin receptor through both the alpha and beta subunits.

We have recently shown that the beta subunit of thyrotropin (TSH) can be cross-linked to the TSH receptor [Buckland, Strickland, Pierce & Rees Smith (1985) Endocrinology (Baltimore) 116, 2122-2124; Buckland, Strickland & Rees Smith (1985) Biochem. Soc. Trans. 13, 942-943]. We failed, however, to cross-link the alpha subunit to the receptor, leaving the role of this subunit in the TSH-TSH-receptor interaction uncertain. We now report the successful cross-linking of the TSH alpha subunit to the receptor by the use of two different cross-linking reagents. Our studies suggest therefore that both subunits of TSH form part of the hormone's receptor-binding site.

Azides↗
PubMed1986

Assessment of the shape and molecular size of TSH-TSH receptor complexes.

Photoaffinity labelling and analysis under denaturing conditions (SDS-PAGE) have shown that the porcine TSH receptor contains an A subunit (Mr = 47,000) which forms the binding site for TSH and a B subunit (Mr = 25,000) linked to the A subunit by a disulphide bridge. In order to assess the size and shape of the receptor under non-denaturing conditions we have solubilized photoaffinity-labelled porcine TSH receptors using the small micelle-sized detergent sodium deoxycholate and analysed the preparations by sucrose density gradient centrifugation and gel filtration. Under these conditions, the cross-linked TSH-TSH receptor complex showed an S20,w of 6.4 S and a frictional ratio f/f0 of 1.8. These values were consistent with those which might be expected from an elongated protein complex with a molecular weight of about 100,000 (the value obtained by SDS-PAGE). Analysis of another thyroid membrane protein, human thyroid microsomal antigen (Mr = 110,000 by SDS-PAGE) under the same conditions gave an S20,w of 6.0 S and f/f0 = 1.3, suggesting that this protein has a compact structure. The TSH receptor A subunit cross-linked to TSH (Mr = 70,000 by SDS-PAGE) gave an S20,w of 4.6 S and f/f0 = 1.8 and these values could be compared with those obtained for the A subunit alone (S20,w = 3.6 S; f/f0 = 1.4; Mr by SDS-PAGE = 47,000) and TSH alone (S20,w = 2.6 S; f/f0 = 1.6; Mr = 28,000.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1986

Computers of the future.

It's been said that today's flights into fantasy become tomorrow's realities. This article is the author's flight into the future of computers.

Animals↗
PubMed1986

Functional assessment of T cell depletion from bone marrow prior to therapeutic transplantation using limiting dilution culture methods.

We evaluate the usefulness of limiting dilution culture methods in assessing the extent of T lymphocyte depletion from bone marrow inocula, prior to transplant, using either ex vivo antibody/complement-mediated depletion or immunotoxin treatment. Complement-mediated depletion using anti-Leu-1 antibody was shown to result in a consistent decline of 99%-99.9% in the frequencies of T cells able to proliferate in mitogen-stimulated, interleukin-2 (IL-2)-supplemented cultures. Equivalent declines were demonstrated in frequencies of "helper" T cells able to respond to mitogen by making IL-2, and in "killer" T cells able to give rise to clones of cytotoxic effectors. In most experiments, a second cycle of anti-Leu-1 + complement treatment did not further diminish the fraction of proliferating cells, although T cells able to secrete IL-2 were additionally depleted following a second cycle of antibody and complement. The limiting dilution methods were found to be at least as sensitive as flow cytometric (FACS) methods for detecting residual T cell contamination after protocols involving complement-mediated lysis, and superior to FACS analysis for protocols involving T cell depletion by a ricin A chain-anti-T101 immunotoxin, in which treated T cells suffer functional impairment and eventual death after exposure to immunotoxin, but remain phenotypically detectable during FACS analysis. Although limiting dilution methods do not provide data as rapidly as FACS analyses, they do not require a cytofluorimeter, provide equal or greater sensitivity, and can assess functional impairment, for both helper and killer T cell sets, even in situations in which the depletion procedure does not lead to immediate cytolysis.

Antibodies↗
PubMed1986

Comparative in vitro antimicrobial activity of carumonam, a new monocyclic beta-lactam.

The antimicrobial activity of carumonam (formerly RO-17-2301), a monocyclic beta-lactam antibiotic, was compared with those of aztreonam, cefotaxime, cefoperazone, ceftazidime, piperacillin, and gentamicin against 455 bacterial isolates. Carumonam did not possess activity against gram-positive cocci and was generally comparable to aztreonam and ceftazidime for most gram-negative bacilli. However, carumonam was the most active beta-lactam against gentamicin-resistant Pseudomonas aeruginosa strains (90% MIC, 8 micrograms/ml).

Anti-Bacterial Agents↗