IL-6 rescues resting mouse T cells from apoptosis.
It has previously been demonstrated that mature mouse T cells live for many weeks in vivo. In contrast, explanted lymph node or splenic T cells undergo spontaneous death within days, suggesting that survival factors supplied in vivo are not present in normal tissue culture medium. We discovered that IL-6 can rescue resting T cells from apoptosis in vitro. We show that recombinant mouse IL-6 as well as IL-6 in endothelial cell supernatants are sufficient to rescue T cells from death in the absence of additional cytokines. We show that CD4+ T cells express Bcl-2 immediately following isolation from the mouse, but after 24 h in culture Bcl-2 is undetectable. If during this time period the T cells are incubated with rIL-6, Bcl-2 expression is not down-regulated. It is, therefore, possible that IL-6 rescue from death is mediated by maintenance or induction of Bcl-2 expression. Addition of rIL-6 does not by itself induce blastogenesis or proliferation, and therefore, this cytokine appears to be a true survival factor rather than a mitogenic factor for resting T cells. Together, these results support a potential role for IL-6 as one of the factors important for prolonging resting T cell survival in vivo.
Teague
T K
TK
Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206, USA.
Marrack
P
P
Kappler
J W
JW
Vella
A T
AT
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015704:CD4 Antigens / Q000032:analysis; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000737:chemistry; D015850:Interleukin-6 / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000502:physiology*
D015704:CD4 Antigens; D015850:Interleukin-6; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins