Sex chromatin analysis of lymphocytes invading host organs in transfusion-associated graft-versus-host disease

We report a method of sex chromatin analysis of lymphocytes separated from host organs in transfusion-associated graft-versus-host disease (GVHD), which enabled the demonstration of invasion by donor lymphocytes. The lymphocytes examined were separated from deparaffinized tissue blocks of skin, spleen and bone marrow from two female patients with transfusion-associated GVHD by incubation in 0.5% pepsin. The tissues had been removed at autopsy and fixed in formalin. Sex chromatin analysis was performed by fluorescence microscopy on separated lymphocytes stained with 0.005% quinacrine dihydrochloride. By this means Y chromatin-positive (i.e. male) lymphocytes were demonstrated in the skin, spleen and bone marrow of both female patients.     

Sclerodermatous chronic graft-versus-host disease induced by host T-cell-mediated autoimmunity

Despite a long-standing hypothesis that chronic graft-versus-host disease (cGVHD) is an autoimmune disorder, most mouse models of cGVHD have been developed on the assumption that donor T cells are essential for its development. Here we show that cGVHD may be caused by autoreactive host T cells in mice that have been lethally irradiated and grafted with T-cell-depleted allogeneic bone marrow cells. In this chimera, host T cells derived from radioresistant intrathymic T-cell precursors caused dermal fibrosis and periportal inflammation, without the requirement for donor T cells. The lack of host DCs within the thymus after high-dose irradiation allowed autoreactive host T cells to escape thymic negative selection. Moreover, the homeostatic expansion of these T cells may augment their autoreactivity. These findings indicate that host T-cell-mediated cGVHD is an autoimmune process that occurs following the grafting of T-cell-depleted BM cells into hosts with functioning thymuses. We propose, based on the present data, that host T-cell-dependent autoimmunity is a potential mechanism by which cGVHD is induced.     

Acute graft-versus-host disease does not require alloantigen expression on host epithelium

Alloantigen expression on host antigen-presenting cells (APCs) is essential to initiate graft-versus-host disease (GvHD); therefore, alloantigen expression on host target epithelium is also thought to be essential for tissue damage. We tested this hypothesis in mouse models of GvHD using bone-marrow chimeras in which either major histocompatibility complex class I or class II alloantigen was expressed only on APCs. We found that acute GvHD does not require alloantigen expression on host target epithelium and that neutralization of tumor necrosis factor-alpha and interleukin-1 prevents acute GvHD. These results pertain particularly to CD4-mediated GvHD but also apply, at least in part, to CD8-mediated GvHD. These results challenge current paradigms about the antigen specificity of GvHD effector mechanisms and confirm the central roles of both host APCs and inflammatory cytokines in acute GvHD.     

胞内致病菌入侵宿主细胞分子机理研究进展

胞内致病菌,指能够侵入宿主细胞且在宿主细胞内存活并繁殖的病原菌。其入侵宿主细胞的过程主要涉及细菌黏附宿主细胞、侵袭、细菌在细胞内存活以及引起宿主细胞损伤等。先前的研究表明大多数胞内致病菌是通过吞噬细胞被动地摄取,而随着分子生物学和免疫学的发展,越来越多的胞内致病菌被证明能主动入侵到宿主细胞体内,并进化出各种调控宿主细胞信号通路的方式。本文讨论了胞内致病菌在入侵宿主细胞时各阶段的共同的分子机制以及常见的胞内致病菌所采取的入侵策略,并对近年来国内外主要相关研究进展做一总结。     

Clonal analysis of the T lymphocytes involved in parent versus Fn1 graft-versus-host reaction

A systemic graft-versus-host reaction (GVHR) leading to 50% mortality by day 20 was elicited by the injection of CBA (10⁵) or B10 (10⁶) parental T lymphocytes into irradiated (750 rad) and bone marrow protected (CBA x B10)F₁ recipients. Between days 12 and 28 the spleens of the sick mice were analyzed by limiting dilution, performed with irradiated F₁ cells and a source of interleukin-2 (IL-2), to determine the frequency of cells with an antihost proliferative or cytolytic activity and to derive T lymphocyte clones. The frequency of cells with antihost proliferative or cytolytic activity was approximately 10^–3 in either combination. In the CBA vs F₁ GVHR, all eight clones isolated with anti-F₁ activity were Lyt-2^–, noncytolytic, mixed lymphocyte reaction (MLR) responders and IL-2 producers, three of which mapped to the A ^b locus, while in the B10 anti-F1 combination, eight of the nine anti-F₁ clones isolated were Lyt-2⁺, poor MLR responders and non-IL-2 producers, but cytolytic and mapping to K _k . These findings suggest a much higher frequency of T cells recognizing the A-locus antigens in the CBA than in the B10 strain.