ACTIVATION AND ACTIVATION-INDUCED DEATH OF HUMAN TONSILLAR B-CELLS AND BURKITT-LYMPHOMA CELLS - LACK OF CD95 (FAS APO-1) LIGAND EXPRESSION AND FUNCTION/
Pt. Daniel et al., ACTIVATION AND ACTIVATION-INDUCED DEATH OF HUMAN TONSILLAR B-CELLS AND BURKITT-LYMPHOMA CELLS - LACK OF CD95 (FAS APO-1) LIGAND EXPRESSION AND FUNCTION/, European Journal of Immunology, 27(4), 1997, pp. 1029-1034
Activation of T cells was shown to up-regulate the Fas ligand (Fast) w
hich binds to the CD95 (APO-1/Fas) antigen and mediates activation-ind
uced cell death (AICD) of activated T cells and T lymphoma cells. A re
cent report showed that mouse B cells express the Fast upon activation
with lipopolysaccharide (LPS). We therefore asked whether activation
of human B cells induces expression of Fast and whether AICD is mediat
ed, as in T cells, through autocrine production of the Fast. We used h
uman tonsillar B cells and Burkitt lymphoma cell lines which were acti
vated by CD40 ligand, surface (s)IgM cross-linking, or LPS. Northern a
nd Western blot analysis failed to detect Fast during B cell activatio
n or AICD of both normal and malignant B cells. Low-level expression o
f Fast was detected by reverse transcriptase-polymerase chain reaction
. Functional experiments, however, showed that Fast is not functionall
y expressed upon activation. IgM-mediated AICD in the tonsillar or Bur
kitt lymphoma B cells could not be inhibited by Fast blocking. Thus, o
ur data show that, in contrast to T cells, activation of normal or mal
ignant human B cells does not lead to functional Fast expression.