CUTTING EDGE - ANTIGEN-DEPENDENT REGULATION OF TELOMERASE ACTIVITY INMURINE T-CELLS

Telomeres, structures on the ends of linear chromosomes, function to m aintain chromosomal integrity, Telomere shortening occurs with cell di vision and provides a mechanism for limiting the replicative potential of normal human somatic cells. Telomerase, a ribonucleoprotein enzyme , synthesizes telomeric repeats on chromosomal termini, potentially ex tending the capacity for cell division. The present study demonstrates that resting T cells express little/no activity, and optimal Ag-speci fic induction of telomerase activity in vitro requires both TCR and CD 28-B7 costimulatory signals. Regulation of telomerase in T cells durin g in vivo Ag-dependent activation was also assessed by adoptive transf er of TCR transgenic T cells and subsequent Ag challenge. Under these conditions, telomerase was induced in transgenic T cells coincident wi th a phase of extensive clonal expansion, These findings suggest that telomerase may represent an adoptive response that functions to preser ve replicative potential in Ag-reactive lymphocytes.