Transforming growth factor-beta 2 induces apoptosis of murine T cell clones without down-regulating bcl-2 mRNA expression

Transforming growth factor-beta (TGF beta) is a potent immunosuppressive cytokine which inhibits the antigen (Ag)-dependent expansion of T cells both in vitro and in vivo by mechanisms not well defined yet. Here we report that exposure of interleukin (IL)-2-dependent T cell lines to TGF beta 2 results in apoptosis defined by morphology, nucleosomal size DNA fragmentation and in situ DNA end labeling. TGF beta 2-induced T cell apoptosis showed the following characteristics: (1) in contrast to the rapid evolution of apoptosis following IL-2 deprivation, apoptosis of T cells triggered by TGF beta 2 was delayed; (2) cycloheximide prevented TGF beta 2-induced apoptosis of CTLL-2 but not of OVA-7 T helper cells; (3) in contrast to apoptosis following IL-2 deprivation, TGF beta 2-mediated T cell apoptosis was not associated with decreased expression of the proto-oncogenes, bcl-2 or c-myc; (4) TGF beta 2-induced apoptosis was not restricted to IL-2-dependent T cell lines since the IL-4-dependent T cell line, CT.4S, as well as EL4 lymphoma cells, which grow independently of exogenous IL-2, were also susceptible to TGF beta 2-mediated apoptosis. Taken together, these data may present a novel mechanism of TGF beta 2-mediated suppression of T cell expansion in response to Ag and IL-2, the activation of the endogenous death program of apoptosis, which appears to operate independently of direct interactions of TGF beta 2 with the IL-2/IL-2 receptor system.


Published in:
European journal of immunology, 24, 6, 1293-300
Year:
1994
Publisher:
Wiley-Blackwell
ISSN:
0014-2980
Laboratories:




 Record created 2010-10-21, last modified 2018-03-17


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