T-lymphocyte long-term cultures have a constant histone variant pattern during aging.

ABSTRACT

Human peripheral long-term T-lymphocyte cell cultures show some characteristics similar to those of fibroblast cell lines, the latter of which have been used as in vitro systems for cellular aging studies for many years. Both show a limited in vitro life span, as well as a progressive prolongation of their cell cycle with increasing age. However, whereas T-cell cultures die from apoptosis at the end of their proliferative capacity, fibroblasts can be maintained for long periods of time in stationary cultures as postmitotic senescent cells. Previous studies analyzing the histone variant pattern of a human lung embryonic fibroblast cell line have shown that this pattern changes as a function of cumulative population doublings in a manner not unlike that found in terminally differentiating systems. In the present study the histone variant composition of long-term T-cell cultures was analyzed as a function of population doublings and compared to a human diploid fibroblast system. The results from this study provide a distinction at the molecular level among these two in vitro aging model systems, because it was found that long-term T-cell cultures show a constant histone variant constitution throughout their in vitro life, dissimilar to previous findings using the fibroblast cell system.