PubMed Health⌕ Search

Biomedical subjects

L G Lum

Publications and source records attributed to L G Lum.

At least 91 records · Page 5Linked to original sources
PubMed1982

The regulation of Ig synthesis after marrow transplantation. IV. T4 and T8 subset function in patients with chronic graft-vs-host disease.

This study compares pokeweed mitogen-activated immunoglobulin synthesis functions of T, T4 T8, and B cells from 13 marrow graft recipients with chronic graft-vs-host disease (GVHD), 10 long-term healthy marrow graft recipients, and 20 normal individuals. T cells expressed helper function (greater than 20% of the control) in eight of 10 long-term healthy patients and in only four of 13 patients with chronic GVHD. T4 cells expressed helper activity in all 10 long-term healthy patients, whereas T4 cells in four of 13 chronic GVHD patients did not express helper activity. Chronic GVHD patients had T cells (eight of 13), T4 cells (four of 13), and T8 cells (11 of 13) that suppressed immunoglobulin synthesis by normal T and B cells greater than 50%; radiosensitive and radioresistant suppressors were detected. Three of 10 patients with chronic GVHD and one of the long-term healthy patients had T4 cells that exhibited suppression. T cells from all 20 normal individuals expressed help and none suppressed immunoglobulin production. Altered T, T4, T8, and B cell functions were more frequent in patients with chronic GVHD than in long-term healthy patients or normals. Variable function within a T cell phenotype, variable radiosensitivity of suppressor cells, and higher frequencies of altered function in patients with chronic GVHD suggest there are different maturational stages expressed in each T cell phenotype.

Antibody-Producing Cells↗
PubMed1982

Immunoglobulin production after marrow transplantation. III. The functional heterogeneity of FC-IgG receptor positive and negative T cell subpopulations.

Ten patients with chronic graft-versus-host disease (GVHD) after HLA-identical marrow transplantation were studied between 372 and 1649 days post-transplant for their T cell subset functions in pokeweed mitogen-stimulated immunoglobulin (Ig) synthesis. In vitro Ig synthesis was assessed using an indirect haemolytic plaque assay after 6 days of culture. T cells, TG+ cells (Fc-IgG receptor positive), TG- cells (Fc-IgG receptor negative), and B cell-enriched populations from the patients were co-cultured with normal T and/or B cells. Such cultures in patients with chronic GVHD showed deficient B cell activity (eight of 10); and deficient helper activity in T cells (six of 10), TG+ cells (five of nine), and TG- cells (three of nine). Greater than 50% suppression of Ig synthesis was detected with T cells (four of 10), TG+ cells (three of 10), and TG- cells (three of 10). This study provides evidence for variable regulatory function of Fc receptor T cell subsets in patients with chronic GVHD. The unexpected finding was that TG+ and TG- subpopulations can lack helper activity or actively suppress Ig synthesis.

B-Lymphocytes↗
PubMed1982

In vitro regulation of immunoglobulin synthesis after human marrow transplantation. II. Deficient T and non-T lymphocyte function within 3-4 months of allogeneic, syngeneic, or autologous marrow grafting for hematologic malignancy.

Immunoglobulin secretion was studied in 37 patients between 19 and 106 days after allogeneic HLA-identical (30 patients), allogeneic one HLA-haplotype-identical (three patients), syngeneic (three patients), or autologous (one patient) marrow grafting. E rosette-positive (T) and E rosette-negative (non-T) peripheral blood mononuclear cells were cocultured with pokeweed mitogen for 6 days. Polyvalent immunoglobulin secretion was determined by counting plaque forming cells in a reverse hemolytic plaque assay. The number of antibody secreting cells in cocultures of autologous T and non-T lymphocytes was low in 40 of 44 tests conducted on samples from the 37 patients. Mononuclear or non-T cells from 38 of 40 tests failed to produce antibody when cultured with normal helper T cells. T cells from 23 of 37 tests failed to help normal non-T cells secrete antibody. T lymphocytes from 23 of 41 tests suppressed antibody production greater than 80% by normal T and non-T cells. The suppressor cells were radiosensitive in 17 of the 25 tests. The abnormal function of lymphocyte subpopulations in patients during the first 3 mo after syngeneic, allogeneic or autologous marrow grafting was similar regardless of the type of graft or the presence of acute graft versus host disease.

Acute Disease↗
PubMed1981

In vitro regulation of immunoglobulin synthesis after marrow transplantation. I. T-cell and B-cell deficiencies in patients with and without chronic graft-versus-host disease.

Twenty-four patients with aplastic anemia or acute leukemia were treated by marrow grafts from HLA-identical donors after conditioning with high doses of cyclophosphamide and/or today body irradiation. They were studied between 4 and 63 mo (median 14.2) after transplantation. Seventeen patients had chronic graft-versus-host disease (C-GVHD) and 7 were healthy. They were studied for defects in their T- and B-cell function using and indirect hemolytic plaque assay for Ig production after 6 days of culture in the presence of pokeweek mitogen. T or B cells from the patients with or without C-GVHD were cocultured with T or B cells from their HLA-identical marrow donors or unrelated normal controls. Intrinsic B-cell defects, lack of helper T-cell activity, and suppressor T-cell activity were more frequently found in patients with C-GVHD than in healthy patients. Fifteen of the 17 patients with C-GVHD showed on or more defects in their T-and B-cell function compared to only 3 of the 7 patients without C-GVHD. None of the healthy controls, including the marrow donors, showed defects in their T- and B-cell functions. These in vitro findings may be helpful in assessing the process of immune reconstitution and the immunologic aberration found after human marrow transplantation.

B-Lymphocytes↗
PubMed1980

Splenectomy in the management of the thrombocytopenia of the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome is an X-linked immunodeficiency disorder consisting of the triad of frequent infections, eczema, and profound thrombocytopenia. We evaluated the effects of splenectomy on hemostatic improvement and subsequent clinical course in 16 patients with the Wiskott-Aldrich syndrome. All 16 had an increase in platelet counts to at least 100,000 per cubic millimeter after splenectomy, with the mean increasing from 19,900 per cubic millimeter preoperatively to 262,700 per cubic millimeter after splenectomy. In addition, platelet size, which is characteristically small in this disease, also became normal. Survival after splenectomy correlated with the prophylactic use of antibiotics. Five of seven patients not taking prophylactic antibiotics died of sepis within 33 months of surgery. The mean survival of the nine patients maintained with prophylactic antibiotics, however, was at least 91.4 months, with six of these patients still alive an average of 11.0 years or more after splenectomy. Thus, splenectomy is a useful therapy for a major cause of morbidity and mortality in this complex syndrome.

Adolescent↗
PubMed1979

MICC cytotoxic effector function of human T lymphocyte subpopulations bearing Fc-receptors for IgG and IgM.

Purified subpopulations of human T lymphocytes bearing Fc-IgG and Fc-IgM receptors were studied for their ability to mediate mitogen (PHA) induced cellular cytotoxicity (MICC) to chicken erythrocyte (CRBC) and DBA/Mastocytoma P815Y tumour cell targets. There were marked differences in the ability of the Fc-IgG receptor-bearing T cell (T gamma) and the Fc-IgM (T mu) to mediating MICC to CRBC and P815Y target cells. T gamma cells were very efficient killers of CRBC and T mu cells had no cytotoxic activity to CRBC. On the other hand, both the T gamma and T mu subpopulations were able to mediate MICC to P815Y tumour cell targets.

Cytotoxicity, Immunologic↗
PubMed1979

A receptor for IgA on human T lymphocytes.

Receptors for IgA antibody-antigen complexes were demonstrated on 2 to 18% (mean 6.7%) of human peripheral blood T cells. The proportion of cells bearing detectable IgA receptors was low in freshly prepared T cells and increased in number after 18 to 24 hr of culture similar to the time course of appearance of the Tmu receptor. These T receptors were shown to be distinctly different from Fc-IgM and Fc-IgG receptors on T cells by blocking studies with purified IgA, IgG, and IgM.

Animals↗
PubMed1979

Fc receptors for IgA on human B, and human non-B, non-T lymphocytes.

Recently, receptors for IgA were demonstrated on subpopulations of human T lymphocytes. In this report, TNP-modified ox erythrocytes coated with the IgA myeloma MOPC-315 were used to detect IgA receptor-bearing lymphocytes within the human non T cell lymphocyte population. A mean of 5.3% (range 2.9 to 12.4%) of E-rosette negative human lymphocytes bound IgA-coated indicator cells. Blocking studies with soluble IgA, IgG, and IgM demonstrated that the IgA receptors on the non-T cell populations were separate and distinct from the Fc-receptors for IgG and IgM. Fractionation of the non-T lymphocytes on anti-human (Fab)2 columns into sIg+ and sIg- populations or by rosetting with EAC to provide CRL+ and CRL- populations demonstrated that Fc-IgA receptors were present on a subpopulation of sIg+, CRL+ lymphocytes, and also on sIg- (non-T, non-B) lymphocytes.

Animals↗
PubMed1977

The effect of cuff width on systolic blood pressure measurements in neonates.

The width of the blood pressure cuff was found to have an effect on the accuracy of systolic blood pressure measured in the arm and thigh in neonates. Data were collected in 26 infants of a variety of birth weights and gestational ages. They show that the effect of cuff size can be minimized by selecting a cuff width equal to approximately 50% of the extremity circumference.

Arm↗