Expression of B220 on activated T cell blasts precedes apoptosis.
Superantigens are bacterial or viral products that polyclonally activate T cells bearing certain TCR beta chain variable elements. For instance, Vbeta8+ T cells proliferate in response to staphylococcal enterotoxin B (SEB) in vivo and then undergo Fas- and/or TNF-mediated apoptosis. We have recently shown that apoptotic SEB-reactive T cells express the B cell marker B220. Here we report the identification of a novel subset of CD4+ B220+ T cell blasts that are the precursors of these apoptotic cells in SEB-immunized mice. Moreover, we show that the CD4- CD8- B220+ T cells that accumulate in the lymphoid organs of Fas ligand-defective gld mice stably express a form of the B220 molecule which exhibits biochemical similarities to that expressed by activated wild-type T cells, but is distinct from that displayed on the surface of B cells. Surprisingly, we also find a population of CD4+ B220+ pre-apoptotic T cells in FasL-defective gld mice, arguing that these cells can be generated in a Fas-independent fashion. Collectively, our data support a general model whereby upon activation, T cells up-regulate B220 before undergoing apoptosis. When the apoptotic mechanisms are defective, T cells presumably down-regulate their coreceptor molecules but retain expression of B220 as they accumulate in lymphoid organs.
Renno
T
T
Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland.
Attinger
A
A
Rimoldi
D
D
Hahne
M
M
Tschopp
J
J
MacDonald
H R
HR
D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D015153:Blotting, Western; D015704:CD4 Antigens / Q000032:analysis; D004768:Enterotoxins / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000032:analysis / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D008232:Lymphoproliferative Disorders / Q000235:genetics / Q000276:immunology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013211:Staphylococcus aureus / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000201:enzymology* / Q000276:immunology*; D015854:Up-Regulation / Q000276:immunology
D017304:Annexin A5; D015704:CD4 Antigens; D004768:Enterotoxins; C031818:enterotoxin B, staphylococcal; D017493:Leukocyte Common Antigens