No abstract available

[en] The phenotypic appearance of cell surface antigens on murine thymocytes from long-term radiation bone marrow chimeras was analyzed using indirect immunofluorescence and flow microfluorometry. Cells maturing in the thymi of these mice were typed for MHC (Kk, I-Ak, H-2b, Kb, and Ib) and non-MHC (Lty 1, Ly 9, and TL) determinants. All cells were of donor origin as determined by non-MHC (Ly) phenotype in P1 leads to P2, P1 x P2 leads to P1, and P1 leads to P2 radiation chimeras. In contrast, the MHC phenotypes of these thymocytes were markedly affected by the host environment. Specifically, H-2 and I-A determinants of both parental phenotypes were detected on thymocytes from P1 leads to P1 x P2 chimeras; I-A determinants of host phenotype were present, whereas I-A determinants of donor phenotype were reduced on thymocytes from P1 x P2 leads to P1 chimeras; and thymocytes from P1 leads to P2 chimeras possessed H-2 and I-A determinants of host phenotype but showed reduction of donor I-A phenotype determinants. The appearance of host cell surface H-2 and I-A determinants on thymocytes from chimeras closely parallels the functional recognition of MHC determinants by T cells from chimeric mice and thus may be significantly related to the development of the self-recognition repertoire by maturing T cells

[en] In this study the cytotoxic T lymphocyte (CTL) recognition pattern of thymocytes from recently reconstituted parent leads to F1 and F1 leads to parent radiation bone marrow chimeras was investigated. Chimeric thymocytes were entirely of donor origin approximately 4 weeks after irradiation and reconstitution but were not capable of autonomously generating either alloreactive or trinitrophenyl (TNP)-modified-self-reactive CTL responses. These experiments demonstrte that even at the earliest time CTL effectors of donor origin from the thymuses of chimeras can be studied, their self-receptor repertoire has already been restricted to recognition of host MHC determinants. These results support the cocept that the host environment influences the self-recognition capacity of T cells at the pre- or intrathymic stage of differentation

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No abstract available

[en] In vitro primary antibody responses to limiting concentrations of trinitrophenyl (TNP)-Ficoll were shown to be T cell dependent, requiring the cooperation of T helper (TH) cells, B cells, and accessory cells. Under these conditions, TH cells derived from long-term radiation bone marrow chimeras were major histocompatibility complex (MHC) restricted in their ability to cooperate with accessory cells expressing host-type MHC determinants. The requirement for MHC-restricted self-recognition by TNP-Ficoll-reactive B cells was assessed under these T-dependent conditions. In the presence of competent TH cells, chimeric B cells were found to be MHC restricted, cooperating only with accessory cells that expressed host-type MHC products. In contrast, the soluble products of certain monoclonal T cell lines were able to directly activate B cells in response to TNP-Ficoll, bypassing any requirement for MHC-restricted self-recognition. These findings demonstrate the existence of a novel cell interaction pathway in which B cells as well as TH cells are each required to recognize self-MHC determinants on accessory cells, but are not required to recognize each other. They further demonstrate that the requirement for self-recognition by B cells may be bypassed in certain T-dependent activation pathways

[en] The goals of the present study were: (a) to generate antigen-specific L3T4+ cytolytic T lymphocytes (CTL), (b) to determine their major histocompatibility complex (MHC) restriction specificity, and (c) to assess the influence of thymic MHC determinants on their self specificity. The authors found that L3T4+ CTL specific for either trinitrophenyl (TNP)-modified self determinants or minor histocompatibility antigens could be generated from Lyt-2- responder T cells provided that the response cultures were supplemented with supernatants rich in helper factors. Such antigen-specific L3T4+ CTL were Ia-restricted by the criteria that they lysed only Ia+ target cells and that their lysis of Ia+ target cells was specifically inhibited by anti-Ia monoclonal antibodies. The relative frequency of L3T4+ pCTL was found to be only 5-10% of the total anti-TNP pCTL present in the spleens of normal mice. Finally, the authors utilized radiation bone marrow chimeras to assess the influence of the thymic haplotype on the self-Ia specificity of L3T4+ CTL. Both bulk culture and limiting dilution experiments revealed that the self-Ia specificity of L3T4+ anti-TNP CTL from F1----parent and A----B allogeneic chimeras was not markedly skewed toward the haplotype of the chimeric thymus. These results contrast with those obtained previously for L3T4+ anti-TNP Th cells and demonstrate that in the radiation bone marrow chimera model of T cell differentiation, the self specificity of Th cells but not pCTL is markedly influenced by the haplotype of the chimeric thymus

[en] A general theoretical approach based on the results of statistical optics is used for the analysis of the transverse coherence properties of 3-rd generation synchrotron sources and X-ray free-electron lasers (XFEL). Correlation properties of the wave elds are calculated at different distances from an equivalent Gaussian Schell-model source. This model is used to describe coherence properties of the five meter undulator source at the synchrotron storage ring PETRA III. In the case of XFEL sources the decomposition of the statistical fields into a sum of independently propagating transverse modes is used for the analysis of the coherence properties of these new sources. A detailed calculation is performed for the parameters of the SASE1 undulator at the European XFEL. It is demonstrated that only a few modes contribute significantly to the total radiation field of that source. (orig.)

[en] Abstract only

[en] The present report has used fully H-2 allogeneic radiation bone marrow chimeras to assess the role of host restriction elements in determining the self-specificity of Ia- and H-2K/D-restricted T cells that participate in the generation of trinitrophenyl (TNP)-specific cytotoxic T lymphocytes (CTL). It was demonstrated that there exists a stringent requirement for the recognition of host thymic-type Ia determinants, but there exists only a preference for host thymic-type H-2K/D determinants. Indeed, once the stringent requirement for recognition of host Ia determinants was fulfilled, anti-TNP CTL were generated in response to TNP-modified stimulators that expressed either donor-type or host-type H-2K/D determinants. The CTL that were generated in response to TNP-modified donor-type stimulators were shown to be specific for TNP and restricted to the non-thymic H-2K/D determinants of the chimeric donor. Thus, these results demonstrate in a single immune response that the thymic hypothesis accurately predicts the self-specificity expressed by Ia-restricted T cells, but does not fully account for the self-specificity expressed by H-2K/D-restricted T cells. These results are consistent with the concept that H-2K/D-restricted T cells, but not Ia-restricted T cells, can differentiate into functional competence either intrathymically or extra-thymically. The results demonstrate that the generation of anti-TNP CTL responses involve two parallel sets of major histocompatibility complex-restricted cell interactions, an Ia-restricted TH-accessory cell interaction required for TH cell activation, and an H-2K/D-restricted pCTL-stimulator cell interaction required for pCTL stimulation. The interaction between activated TH cells and stimulated pCTL is mediated, at least in part, by nonspecific soluble helper factors