0000000000422106
AUTHOR
Martin Krönke
Frequency-Analysis of Precursors of Cytotoxic T Lymphocytes in Radiation Chimeras: Enumeration of Antigenspecific CTL-P Restricted to Thymic MHC- and Bone Marrow-MHC-Determinants
The mechanisms controlling the acquisition of T cell restriction specificity and immunocompetence are, despite of numerous investigations, not well understood. From studies of the CTL-immune responsiveness in thymus- and bone marrow-grafted chimeric mice, it became apparent, that it is the thymus which is crucial not only for the maturation or T cells, but also for the specificity repertoire of the T cells (1,2). From these data it was suggested, that during intra-thymic maturation both mutational events and positive selection mechanisms influence the repertoire such that only T cells restricted to thymic epithelial cell MHC determinants mature and will be exported to the peripheral lymphoi…
Interleukin-2 receptor gene expression by bronchoalveolar lavage lymphocytes in pulmonary sarcoidosis.
Current concepts of the immunopathogenesis of sarcoidosis favor a central role of activated, interleukin-2 (IL-2) producing helper T-cells at sites of inflammation. Normally, activated T-cells release IL-2 and express IL-2 receptors (IL-2R). IL-2R+ cells, however, are not uniformly found in patients with clinically active disease. To determine whether the lack of IL-2R+ cells is caused by a dysregulation of the IL-2R gene or by the mode of T-cell activation in pulmonary sarcoidosis, we quantified IL-2 and IL-2R m-RNA transcripts, IL-2 release, and IL-2R surface protein in peripheral blood lymphocytes of patients with sarcoidosis and normal control subjects before and after in vitro stimulat…
Functional Analysis of Alloreactive Helper T Cells Involved in the Induction of Cytolytic T Cell Responses In Vitro
When T-responder cells are sensitized in vitro to foreign antigen presented on syngeneic cells or towards allogeneic stimulator cells, a proliferative response is initiated in which antigen specific cytotoxic T lymphocytes (CTL) are generated. The induction of CTL, however, requires the collaboration between functionally distinct T cell subpopulations1–5 and accessory cells from the macrophage lineage, including dendritic cells. The experimental data accumulated so far reveal a cascade of T-T cell interactions and distinct functions of their soluble products resulting in the “Interleukin concept”6 (Fig. 1). Upon receptor-antigen interaction, the “antigen-selected” clones of CTLp become sens…
Linkage of C4 and C4 deficiency to BF and GPLA
The C4, Bf, and GPLA phenotypes of homo- and heterozygous C4-deficient guinea pigs were studied. The electrophoretic patterns suggest that the deficiency in circulating C4 results from an impaired structural gene, allelic to the C4F, C4S, and C4S1 alleles at the C4 locus. In family studies, support for linkage of C4 and Bf to theGPLA system was obtained. The defective gene appears to be the fourth allele, which is rare, in the polymorphism of the fourth component of guinea pig complement.
Quantitative representation of all T cells committed to develop into cytotoxic effector cells and/or interleukin 2 activity-producing helper cells within murine T lymphocyte subsets
A limiting dilution culture system based on stimulation with concanavalin A (Con A) has been used to study the quantitative distribution of helper and of cytotoxic precursor cells in Lyt-2-defined subpopulations of murine T cells. Virtually all of the selected Lyt-2+ and Lyt-2-T cells grow and expand to large clonal colonies within an 8-9-day culture period. Our data show that upon stimulation with Con A, 90% of the Lyt-2-T cells were capable to produce interleukin 2 (IL 2) activity. In addition, IL 2 activity is produced by 8-10% of Lyt-2+ T cells. However, at the clonal level, the average of the IL2 activity produced by Lyt-2+ T cells is about 8-fold less as compared to Lyt-2-T cells. Pre…