A new LIM protein containing an autoepitope homologous to "senescent cell antigen".

Autoantibody eluted from aged human red blood cells was used to immunoscreen a human fetal liver expression library and led to the isolation of a cDNA encoding a novel 35.8 kDa protein with five LIM domains. An autoepitope homologous to the "senescent cell antigen" on the red blood cell membrane anion exchange protein identified by Kay et al. (P.N.A.S. 87:5734, 1990) was present in the first zinc finger of the third LIM domain. The gene for this novel protein is highly conserved in vertebrates, and its 4.6 kb mRNA is widely expressed in human tissues. Recombinant autoantigens such as the one reported here have potential applications in vitro for the purification, identification and quantitation of autoantibodies, and in vivo for the removal of autoantibodies, increasing red blood cell lifespan and reducing the need for transfusion.