U1 10:00 Use of thymectomized xenopus to study extra-thymic T cell and NK cell evolution

Apoptosis‐Specific Protein (ASP) Identified in Apoptotic Xenopus Thymus Tumor Cells

“…In this paper, we investigate whether the anti-ASP antibody used by Grand et al (1995) can identify conserved apoptosis-specific proteins in Xenopus, whose immune system development is being explored in depth (Du Pasquier et al, 1996;Horton et al, 1996a). Our studies center on Xenopus thymus tumor-derived lymphoid-cell lines B3B7 and 15/0 (Du Pasquier and Robert, 1992;Robert et al, 1994), since novel apoptotic markers for these tumor cells, being used as targets for Xenopus cytolytic lymphocytes (for both NK-like cells [Horton et al, 1996b], and T cells [Horton et al, 1997a[Horton et al, , 1997b .…”

“…Detection of apoptotic proteins in Xenopus has been possible not only by fluorescence microscopy of fixed cell smears and by Western blot analysis of cell lysates, but also by flow cytometric analysis of permeabilized unfixed cell suspensions, the latter in itself being a novel finding (contrast methodologies used by Grand et al, 1995). This new and simple methodology for identifying apoptotic Xenopus cells should expedite studies on the development of the Xenopus immune system, such as those investigating the extensive restructuring of immune system cells at metamorphosis (Flajnik et al, 1987;Rollins-Smith and Cohen, 1996) and others (Horton et al, 1996b(Horton et al, , 1997a(Horton et al, , 1997b( studying the mechanism of tumor-cell cytotoxicity induced by cytolytic lymphocytes. (Robert et al, 1994), whereas the 15/0 cell line is derived from a thymus tumor from an LG15 (X. laevis/X, gilli clone 15) clonal Xenopus.…”

“…During ontogeny, T and B lymphocytes that are autoreactive or nonfunctional, due to inappropriate rearrangement of antigen-receptor gene segments, die by apoptosis (Osborne, 1996). Cytolytic lymphocytes (both T and NK cells) kill by inducing apoptosis in their target cells (Berke, 1995) (Duke, 1996).In mammals, apoptosis can be characterized morphologically by cell shrinkage, nuclear pycnosis, chromatin condensation, and plasma membrane blebbing, with rapid phagocytosis of apoptotic cells (Martins and Earnshaw, 1997 [Horton et al, 1996b], and T cells [Horton et al, 1997a[Horton et al, , 1997b Aliquots were also taken for fluorescence microscopic analysis of either acetone-fixed cytospins stained with anti-ASP ( Figure 2E) or unfixed cells stained with acridine orange (Figures 2A to 2D Splenocytes ( Figure 5 and Figure 6). …”

“…In mammals, apoptosis can be characterized morphologically by cell shrinkage, nuclear pycnosis, chromatin condensation, and plasma membrane blebbing, with rapid phagocytosis of apoptotic cells (Martins and Earnshaw, 1997 [Horton et al, 1996b], and T cells [Horton et al, 1997a[Horton et al, , 1997b Aliquots were also taken for fluorescence microscopic analysis of either acetone-fixed cytospins stained with anti-ASP ( Figure 2E) or unfixed cells stained with acridine orange (Figures 2A to 2D Splenocytes ( Figure 5 and Figure 6). …”