The interferon-inducible Staf50 gene is downregulated during T cell costimulation by CD2 and CD28.

It is well established that interferons (IFN) exert potent regulatory effects on the immune system. We have recently isolated a new IFN-induced human cDNA coding for a member of the Ring finger B-box/B30.2 subfamily that localizes to the chromosome band 11p15. We have named it Staf50. We show in this report that Staf50 is expressed in resting T cells in the absence of exogenous IFN treatment and is strongly repressed during T cell activation by anti-CD28 and anti-CD2 monoclonal antibodies (mAb) at both messenger and protein levels. In addition, we show that several members of the Ring finger B-box/B30.2 subfamily, including the 52-kDa SSA/Ro autoantigen, localize to the same chromosome band, 11p15, and are upregulated by IFN. These data led us to define a family of IFN-induced genes clustered on chromosome 11p15 that may be involved in T cell regulatory processes.