Biomedical subjects

J Irsch

Publications and source records attributed to J Irsch.

4 recordsLinked to original sources

PubMed1998

Systemic T-cell unresponsiveness during rush bee-venom immunotherapy.

By rush bee-venom immunotherapy, subjects reacting allergically to the venom can be effectively anergized, although the mechanism of action is not known. Here we analyzed the systemic effects of rush desensitization on the T cells of allergic patients. In most patients, we found reduced frequencies of T cells recalled to express CD69 and the cytokines interleukin (IL)-4 and interferon-gamma (IFN-gamma) after stimulation of peripheral blood mononuclear cells with phorbol 12-myristate 13-acetate (PMA) and ionomycin, as compared with normal donors. These frequencies are progressively reduced during immunotherapy. The frequency of cells expressing IL-2 does not change. A few patients show a different response to immunotherapy: frequencies of cells expressing CD69, IL-4, or IFN-gamma do not change, and remain similar to those of normal donors. However, the frequency of cells able to express IL-2 is increased. The analysis of cytokine expression in CD45RO+ vs CD45RO- T-cell populations revealed differences between normal and allergic donors. In allergic patients, higher frequencies of IL-4- and IFN-gamma-expressing cells among the CD45RO- subpopulation were found than in normal donors. This situation is not modified by immunotherapy. The results reveal a certain degree of heterogeneity in the response of allergic patients to bee-venom rush immunotherapy; however, all are clearly differentiated from normal controls as judged by cytokine expression of CD45RO- T cells. In most allergic patients, a considerable percentage of Th cells become unresponsive to mitogenic stimulation, and may be responsible for the desensitization itself.

Adult↗

PubMed1995

Isolation and characterization of allergen-binding cells from normal and allergic donors.

BACKGROUND: Flow cytometry of the immune system so far has been limited to the analysis of subpopulations according to lineage markers. The cells involved in a particular immune response could not be assayed due to their low frequency. Here we show the potential of antigen-specific high gradient magnetic cell sorting to enrich cells for visualisation in multiparameter cytometry, functional studies and immortalization. OBJECTIVES: The aim of this study was the development of an efficient technology for staining and isolation of antigen-binding cells from human peripheral blood. In particular, allergen-specific cells from normal and allergic donors should be analysed and compared to develop a cellular diagnosis of allergy. STUDY DESIGN: The rare antigen-specific cells were sorted by high-gradient magnetic cell sorting with MACS. Haptenized phospholipase A2 (PLA2), the major allergen of bee venom, or haptenized ParoI, the major allergenic component of Parietaria officinalis, were used as antigens. The cells from normal and allergic donors, binding to the allergen were characterized phenotypically by immuno-fluorescence. Allergen-specific B-cells were immortalized by EBV transformation. RESULTS AND CONCLUSION: Allergen-specific cells can be enriched from blood of both allergic and normal donors to purities of up to 75%, by high gradient magnetic cell sorting. The specificity of labelling with allergen was confirmed by establishing allergen-specific EBV-transformed B-cell lines from the sorted cells. Clear differences exist in the cellular composition of allergen-binding cells from normal compared to allergic donors. In normal donors the allergen-binding cells are B-cells expressing CD19 and CD21. In allergic donors, in addition to allergen-binding B-cells, occurring in about equal absolute numbers as in normal donors, basophilic granulocytes are labeled by allergen. These cells express CD38, CD9 and CD25 on their surface, and stain for IgE.

Allergens↗

PubMed1994

Switch recombination in normal IgA1+ B lymphocytes.

Most B lymphocytes in normal individuals express two classes of cell-surface immunoglobulins, IgM and IgD. The specificity of the two antigen receptors is identical since they are produced by transcription and differential splicing of the same variable region gene segment to the heavy-chain constant region gene segments for both mu and delta heavy chains. B lymphocytes expressing other immunoglobulin isotypes, IgG, IgA, or IgE, are rare and not well characterized. Particularly controversial is the molecular mechanism of their isotype switch. Here we use high-gradient magnetic cell sorting and fluorescence-activated cell sorting to purify surface IgA1-bearing B lymphocytes from human blood for cellular and molecular analysis. These cells express no immunoglobulin class other than IgA1 and are a relatively uniform population with regard to expression of other cell-surface molecules. They are resting cells in terms of cell cycle and activation marker analysis. The molecular basis for class switching in the IgA1+ cells is not differential transcription or splicing. Rather, switch recombination involving deletion of DNA has occurred on both immunoglobulin heavy-chain gene loci, including the allelically excluded one, and appears to have been directed to IgA1 under normal physiological conditions.

Antigens, CD↗

PubMed1993

Evidence for a human IgG1 class switch program.

In activated murine B lymphocytes, immunoglobulin class switch recombination occurs as a highly regulated process which is targeted to distinct switch regions. Here we present first evidence that in human B lymphocytes, switch recombination is targeted to distinct switch regions as well. In a panel of clonally unrelated IgG1-expressing human B cells, immortalized by Epstein-Barr virus (EBV) transformation, seven out of nine cells show switch recombination between S mu and S gamma 1 on both alleles, the active and inactive one. The remaining cells show no switch recombination on the inactive IgH locus. The very strong correlation of switch recombination on both alleles of IgG1-expressing cells proves that class switch recombination to IgG1 is not random but directed in human B lymphocytes.

Alleles↗