PubMed Health⌕ Search

Biomedical subjects

E Nisbet-Brown

Publications and source records attributed to E Nisbet-Brown.

17 recordsLinked to original sources
PubMed1998

Cerebral vasculitis associated with chronic mucocutaneous candidiasis.

Chronic mucocutaneous candidiasis is a heterogenous group of disorders, associated with a variety of autoimmune disorders and a broad spectrum of immune aberrations. We describe 2 patients with chronic mucocutaneous candidiasis who had cerebrovascular disease with severe neurologic sequelae. Results of angiography of cerebral vessels and brain biopsy in one were consistent with the diagnosis of cerebral vasculitis.

Adult↗
PubMed1998

The outcome of patients with hypogammaglobulinemia in infancy and early childhood.

A 10-year prospective cohort study followed the evolution of antibodies in children less than 4 years of age with hypogammaglobulinemia. Three patterns were identified: in group 1, immunoglobulins and antibody production normalized;iin group 2, patients continued to have low IgG levels; and in group 3, IgG levels normalized but antibody levels were transient. Statistical analysis showed that invasive infection or low tetanus antibodies at presentation were associated with the development of significant humoral immunodeficiency.

Agammaglobulinemia↗
PubMed1997

Immune function in patients with beta thalassaemia receiving the orally active iron-chelating agent deferiprone.

Short-term deferiprone may reduce body iron in some patients with thalassaemia major. Concerns regarding potential immunosuppressive effects of deferiprone have been raised from results of animal studies and case reports in humans. We studied immune function in 57 thalassaemia patients: 36 treated with deferiprone (L1; CP020) and 21 treated with desferrioxamine (DFO). Circulating B lymphocytes were increased in all patient groups. No differences were detected between treatment groups in percentages of circulating lymphocytes, concentrations of IgG, IgM or IgA, specific antibody titres, complement levels, or in vitro lymphocyte proliferation. No clinically important infections were observed in any patient. These data suggest that no clinical or laboratory changes consistent with immuno-suppression or immunodeficiency are observed during deferiprone therapy.

Adolescent↗
PubMed1994

Lack of correlation between phenotype activation markers of CD8 lymphocytes and cytotoxic T lymphocyte (CTL) function in HIV-1 infection: evidence for rescue with rIL-2.

CTL activity against HIV-1 antigens expressed on HLA-A-matched EBV-transformed B target cells was detected in 33% (6/18) of freshly isolated PBMC (FPBMC) from patients in the early stages of HIV-1 infection (CDCII). No CTL activity was detected in FPMBC in patients with AIDS (CDCIV). However, the presence of CTL activity did not correlate with the expression of CTL activation markers. A dual-color flow cytometric examination revealed that the CD8+ lymphocytes bearing the memory (CD29) and activation (S6F1) surface molecules increased in number as the HIV-1 infection progressed. This functional and phenotypic discrepancy in memory CD8+ lymphocytes suggests that the memory CD8+ lymphocytes have lost cytotoxic function and become "paralyzed" as the HIV disease progresses. Incubation of PBMC of HIV(+) patients with rIL-2 reactivated predominantly HIV-specific CTL. However, rIL-2 stimulation also activated a "polyclonal or polyreactive" cytotoxic function. The reactivation of CTL function is rIL-2 dosage dependent and the amount of rIL-2 required for reactivation is associated with the severity of the disease. HIV antigen specific CTL in HIV(+) patients can be selectively expanded by HIV antigen stimulation in the presence of rIL-2. These results suggest that the in vivo IL-2 deficiency occurring in HIV-1 infection may be responsible in part for the "paralysis" of HIV specific CTL activity. Such activity can be rescued nonspecifically by exogenous rIL-2 stimulation and expanded specifically by HIV-1 antigen stimulation.

Antigens, Surface↗
PubMed1990

CD4+ cytolytic T cell clones that recognize polymorphism of HLA-DR beta 3 chains.

We have investigated HLA-DR beta 3-associated functional polymorphism using selected Epstein-Barr virus (EBV) specific human T cell clones and EBV-transformed B cell (EBV-B) lines. To study the relationship between T cell recognition and the gene products of the three alleles of the DR beta 3 locus, Dw24, 25 and 26 (these were previously called DRw52a, b and c, respectively), CD4+ cytolytic T cell clones (CD4+ CTL) were isolated by repeated stimulation of peripheral blood mononuclear cells (HLA A2 A24; B8 B27; DRw17, Dw24, DRw2) with autologous EBV-B. Clone no. 32 proliferated strongly in response to HLA-Dw24 EBV-B, but not to Dw25 or Dw26 EBV-B. Furthermore, clones no. 32 and no. 45 both lysed HLA-Dw24 EBV-B but not Dw25 or Dw26 EBV-B. In addition, cold target inhibition studies showed that the cytolytic activity of both clones was blocked by unlabelled HLA-Dw24 EBV-B, but not by Dw25 or Dw26 EBV-B. Clones no. 32 and no. 45, therefore, could distinguish between the three allelic products of DR beta 3 haplotypes.

Antigens, Viral↗
PubMed1989

CD4+ cytolytic T cell clones restricted to HLA class II, DR beta I, and DR beta III chains.

We have investigated the functional polymorphism of HLA class II antigens using CD4+ CTL clones. Seven CD4+ CTL clones were isolated from a healthy donor (HLA A2 A24; B8 B27; DRw17 DRw52a) by repeated stimulation with irradiated autologous EBV-transformed B cell lines (EBV-B). According to the HLA restriction specificity we divided CD4+ CTL clones into three subgroups: (i) DRw17-restricted CD4+ CTL clones; (ii) DRw52a-restricted CD4+ CTL clones; and (iii) the CD4+ CTL clones, of which the restriction specificity could not be assigned to products of a single HLA locus. Interestingly, DRw17-restricted CD4+ CTL clones distinguished between DRw17 and DRw18. Similarly, DRw52a-restricted CD4+ CTL clones distinguished between DRw52a, w52b, and w52c. There are four amino acids which differ between DRw17 and DRw18, whereas five differ between DRw52a and the other two alleles (DRw52b and DRw52c). The recent elucidation of the crystal structure of a human class I MHC molecule has identified the probable peptide binding site to be a cleft on the outer surface of the molecule, between two alpha-helices. On the basis of the theoretical model for HLA class II molecules, amino acid positions 26 and 28 (DRw17 vs DRw18) and amino acid positions 26, 28, and 74 (DRw52a vs the other two alleles) lie within the "cleft." We propose that amino acid positions 26 and 28 are very important sites with regard to the recognition of antigen-MHC complex by the TCR.

Binding, Competitive↗
PubMed1987

Major histocompatibility complex (MHC) restricted antigen recognition: high frequency of human T-cell clones recognizing novel MHC class II determinants.

We have used antigen-specific human T-cell clones to study the relationship between MHC and antigen recognition specificities expressed by T cells. Tetanus toxoid (TT)-specific T-lymphocyte clones were derived from a immunized HLA-DR2,7 heterozygous donor by limiting dilution from peripheral blood mononuclear cells (PBM) restimulated with TT in vitro. Clones were screened for MHC-restricted antigen recognition against antigen-presenting cells (APC) from a panel of HLA-typed donors, using an in vitro T-cell proliferation assay. Several distinct patterns of antigen recognition were identified. In addition to T cells that recognized TT in association with donor class II MHC antigens, we found clones that simultaneously expressed self-restricted antigen recognition and alloreactivity, and clones with specificity for antigen in the context of MHC antigens not expressed by the T-cell donor. This was confirmed in inhibition studies using well-characterized monoclonal antibodies against class II MHC antigens to block specific proliferative responses. We propose a possible structure for the determinant recognized by two of the clones. These results suggest that the T-cell antigen receptor undergoes random or antigen-dependent changes in vitro, and that this may be a mechanism for somatic diversification of the T-cell repertoire.

Antibodies, Monoclonal↗
PubMed1986

T lymphocytes from irradiation chimeras repopulated with 13-day fetal liver cells recognize antigens only in association with self-MHC products.

The restriction specificities of maturing thymocytes are determined by the Class II MHC antigens expressed by non-lymphoid thymic tissues. The proliferative response of mature T lymphocytes to antigen-presenting cells (APC) and antigen requires that the APC express the same MHC antigens as the thymus in which the T cells differentiated. Thus, in the two-way bone marrow chimera [A + B----(A x B)F1], T lymphocyte populations of A and B haplotypes have each acquired the potential to recognize antigens associated with either parental haplotype. In spite of the large body of work on MHC restriction, we still do not have a clear understanding of the mechanisms which impose self restriction. The chimeric model systems used previously to study MHC restriction have used adult bone marrow cells as the source of lymphoid precursors. During normal ontogeny, T cells are derived from precursors in the fetal liver and we felt that a direct comparison of T cells from fetal liver and bone marrow-repopulated animals would shed light on the development of MHC restriction specificities during T cell ontogeny in the thymus or prethymically. We found that parental T lymphocyte populations isolated from two-way fetal liver chimeras cooperated only with syngeneic APC, while those from bone marrow chimeras cooperated with APC of either parental haplotype. This suggests that fetal liver and bone marrow may not be equivalent sources of stem cells. Our results may be due to fundamental differences between thymocyte precursors in fetal liver and bone marrow, including the time course of their expression of T cell receptor gene products.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Antigen recognition. V. Requirement for histocompatibility between antigen-presenting cell and B cell in the response to a thymus-dependent antigen, and lack of allogeneic restriction between T and B cells.

The restrictions imposed by the major histocompatibility complex on T-B-antigen-presenting cell (APC) interactions were studied with an in vivo adoptive transfer system, using mutually tolerant T and B cells taken from one-way fetal liver chimeras. It was found that the B cells and adoptive recipient (which provides APC function) have to share determinants encoded by the left-hand end of the H-2 complex for cooperation, whereas there is apparently no such requirement for T-B cell syngeneicity. Suppression arising from allogeneic effects between the host and the transferred T or B cells was excluded by the use of tolerant as well as normal adoptive recipients; both were functionally equivalent. We conclude that under experimental conditions, unrestricted helper T cell function and concurrent APC-B cell genetic restriction can be demonstrated in vivo.

Animals↗
PubMed1981

Is acquired immunological tolerance genetically transmissible?

We have attempted to verify that acquired characteristics can be transmitted through the male germ line by using as a model system the vertical transmission of specific immunological tolerance to major histocompatibility antigens. Tolerant males were a tetraparental mouse and separated parabionts, in each case showing stable lymphoid chimerism. Tolerance in the progeny was assessed by two in vivo assays, rejection of cardiac allografts and clearance of 131I-labeled tumor cells. We were unable to find evidence for heritability of the tolerant state in tetraparental or parabiont males, with either assay system.

Animals↗
PubMedDate not supplied

Antigen-dependent increase in cytosolic free calcium in specific human T-lymphocyte clones.

Calcium has been implicated as an intracellular messenger in the cellular response to various external stimuli. Exposure of lymphocytes to various mitogens and lectins results in rapid transmembrane calcium fluxes and increased cytoplasmic calcium concentrations ([Ca2+]i). It is not clear, however, whether the mechanisms by which these non-physiological stimuli activate cells are related to those involved in antigen-specific activation. We have now used antigen-specific T-cell clones to study changes in [Ca2+]i associated with specific activation and show here that these cells respond specifically in the presence of antigen and antigen-presenting cells (APC) with increased [Ca2+]i and that this increased [Ca2+]i shows the same genetic restrictions as are seen in the proliferation assay. The kinetics of the [Ca2+]i response to antigen indicate that antigen undergoes a time-dependent processing step as a prerequisite for recognition by T cells, as has been shown for T-cell proliferative responses, but that the [Ca2+]i response to processed antigen is extremely rapid. The close correlation between changes in [Ca2+]i and cell activation resulting in proliferation suggests that Ca2+ may act as an intracellular messenger in antigen-specific responses.

Antigen-Presenting Cells↗