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M de Bueger

Publications and source records attributed to M de Bueger.

7 recordsLinked to original sources
PubMed1993

Isolation of an HLA-A2.1 extracted human minor histocompatibility peptide.

Purified HLA-A2.1 molecules obtained by affinity chromatography of 6 x 10(10) Epstein Barr virus (EBV)-transformed B lymphocytes were used in an attempt to isolate the human HLA-A2.1-restricted minor histocompatibility (H) peptides H-Y and HA-2. Fraction 18 of the high-performance liquid chromatography (HPLC)-separated HLA-A2.1 peptide pool was found to contain the natural HA-2 peptide. An HA-2-specific, HLA-A2.1-restricted cytotoxic T lymphocyte clone lysed HLA-A2.1+ HA-2- EBV-transformed B lymphocyte cell lines reproducibly and in a concentration-dependent fashion in the presence of fraction 18, but not in the presence of other HPLC fractions. By contrast, H-Y sensitizing activity was not found in any fraction. Amino acid sequencing of peptide fraction 18 revealed a mixture of peptides with maximal length of nine amino acids, in which the presence of Leu at positions 2 and 9 was dominant. Surprisingly, the HA-2 peptide could not be mimicked by any of the peptide mixtures synthesized according to the amino acid sequences found in fraction 18. Our failure to obtain the actual amino acid sequence of the human minor H peptide HA-2 from a peptide pool with the established pattern for binding to HLA-A2.1 may indicate that this CTL defined minor H peptide does not represent an abundant HLA-A2.1 binding peptide.

Amino Acid Sequence↗
PubMed1993

Human keratinocytes activate primed major and minor histocompatibility antigen specific Th cells in vitro.

Keratinocytes are activated to express MHC class II and ICAM-1 molecules during cutaneous inflammatory reactions. It is controversial how the interaction between these 'nonprofessional' antigen presenting cells (APC) and infiltrating T cells affects the local inflammatory response. To address this issue we analyzed whether IFN gamma-treated cultured human keratinocytes would activate established Th cell clones in vitro. Three allo DR specific T cell clones were induced to proliferate in a HLA-DR and LFA-1/ICAM-1 dependent fashion upon coculture with intact layers of IFN gamma stimulated keratinocytes. Likewise, keratinocytes also could activate two out of four minor histocompatibility (mH) antigen specific Th cell clones obtained from peripheral blood leukocytes (PBL) of graft versus host disease patients. The T cell activating potential of MHC class II+ keratinocytes was shown to be relatively low compared to specialized APC as PMNC and EBV-BLCL. Most strikingly, measurable allo MHC and mH antigen specific Th cell proliferation was only induced by using adherent keratinocytes at low cell densities, but not by keratinocytes in suspension. The results presented here indicate that in vitro conditions may crucially influence observations regarding the T cell activating potential of MHC class II expressing keratinocytes. Furthermore, our results indicate that, in addition to a tolerizing effect as suggested by previous reports, interaction of primed antigen specific T cells with activated keratinocytes may also result in enhancement of a cutaneous immune response in vivo.

Antigen-Presenting Cells↗
PubMed1993

High frequencies of cytotoxic T cell precursors against minor histocompatibility antigens after HLA-identical BMT: absence of correlation with GVHD.

Limiting dilution analysis was used to quantify the frequency of cytotoxic T cell precursors (CTLp) against minor histocompatibility (H) antigens induced by HLA-identical BMT. The development of CTLp was monitored serially in ten patients developing either acute (n = 3), acute and chronic (n = 4) or no (n = 3) GVHD. In blood samples of patients taken shortly after BMT (< 100 days) a high frequency of anti-recipient CTLp was found (mean 1/3433). With time, this value decreased to become undetectable (< 1/500,000) beyond 400 days. This occurred also in patients still suffering from chronic GVHD. In contrast, autologous BMT did not induce any measurable recipient-reactive CTLp at any time point after BMT. In the early phase of reconstitution after BMT the frequency of CTLp against allo HLA-antigens was measured in the same patients. The absence of a consistent increase of allo-specific CTLp indicates that the kinetics of CTLp against host minor H antigens does not merely reflect an overall changed cytolytic potential shortly after BMT. These results indicate that: (1) HLA-identical BMT induces high frequencies of minor H antigen-specific CTLps detectable in the blood during the early phase of reconstitution, and (2) the frequency of recipient-reactive CTL measured in the peripheral blood is not an adequate parameter for GVHD. These data therefore challenge the clinical value of in vitro measurement of recipient-reactive CTLs in the peripheral blood after HLA-identical sibling BMT.

Acute Disease↗
PubMed1992

Tissue distribution of human minor histocompatibility antigens. Ubiquitous versus restricted tissue distribution indicates heterogeneity among human cytotoxic T lymphocyte-defined non-MHC antigens.

We determined the tissue distribution of 7 human minor histocompatibility (H) Ag. Each of these Ag is defined by one or more MHC class I-restricted CTL clones, previously generated from PBL primed against minor H Ag by HLA-identical bone marrow transplantation (BMT). CTL-mediated lysis of tissue-derived cells and cultured cell lines was used as an in vitro assay for minor H Ag expression of several human tissues. The Ag HA-3 (HLA-A1-restricted), HA-4 (HLA-A2 restricted), HA-6 and HA-7 (HLA-B7 restricted), and the male-specific Ag H-Y (HLA-A2 and B7 restricted) were found to be expressed on cells of all tissues tested. In contrast, the HLA-A2-restricted Ag HA-1 and HA-2 were demonstrated on PHA-blasts, EBV-BLCL, purified T cells, B cells, monocytes, and immature thymocytes, but could not be demonstrated on skin-derived cultured fibroblasts, keratinocytes, melanocytes, cultured epithelial cells of kidney proximal tubili, and umbilical cord vein-derived endothelial cells. Incubation of the latter cell lines with rIFN-gamma, rTNF-alpha, and/or rIL-1 alpha, in concentrations shown to maximally increase their susceptibility to lysis by allo-MHC class I CTL, did not induce recognition by HA-1- and HA-2-specific CTL in vitro. These results indicate an ubiquitous tissue expression of the minor H Ag HA-3, -4, -6, -7 and H-Y in contrast to a to the hemopoietic cell lineage-restricted expression for HA-1 and HA-2. The heterogeneity in tissue expression of T cell-defined, class I-restricted non-MHC Ag implies that they might be derived from intracellular proteins with either an ubiquitous or a more specialized cell type-specific function.

Cytotoxicity, Immunologic↗
PubMed1992

Acquired tolerance for minor histocompatibility antigens after HLA identical bone marrow transplantation.

Skin tissue of a healthy chimera 7 years after HLA identical bone marrow transplantation was found to express a minor histocompatibility (mH) antigen against which cytotoxic T lymphocytes (CTLs) had been discovered at a time of acute graft-versus-host disease (aGVHD). We were prompted to investigate the apparent tolerance to this persistent mH antigen and used limiting dilution analysis to monitor in vitro anti-host CTL responses in time after bone marrow transplantation. A high anti-host CTL precursor frequency was found during acute GVHD, declining in time until beyond detection level in the healthy chimera 7 years after transplantation. In this case report (i) CTL precursor frequencies are used for the first time to monitor in vitro tolerance induction to persistent host mH antigens after HLA identical BMT in man; and (ii) it is shown that LDA may be a potential tool for quantification and specificity analysis of CTL responses to mH antigens.

Adult↗