Re: On average, how long do (cytotoxic)T-cells live?

I found a couple articles that will probably answer your question. We 
don't have either journal at our institution, but you could probably find 
them at most major universities.

Tough DF, Sprent J. Lifespan of lymphocytes. Immunol Res 
1995;14(1):1-12.
 
Abstract
T and B lymphocytes comprise heterogeneous populations of cells at 
various stages of differentiation and activation. T- and B-cell subsets 
have different roles in the maintenance of immune homeostasis, and 
their functional differences are reflected by their respective lifespans. 
This review briefly summarizes the available data on lymphocyte 
lifespan, including the kinetics of T- and B-cell development in the 
primary lymphoid organs and the proliferative behavior of naive, 
effector and memory lymphocytes in the peripheral lymphoid 
compartment.

http://www.ncbi.nl
m.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids
=7561338&dopt=Abstract


Tough DF. Sprent J. Life span of naive and memory T cells. Stem 
Cells. 13(3):242-9, 1995

Abstract
The life span of mature T cells is reviewed. Peripheral T lymphocytes 
are a heterogeneous population and comprise a mixture of naive, 
effector and memory cells. The recirculating pool of mature T cells is 
formed during young life through gradual release of naive T cells 
from the thymus. In adults, the pool of mature T cells is relatively 
self-sufficient, and input of new T cells from the thymus declines to 
low levels. Studies on T cell turnover indicate that most peripheral T 
cells can remain in a resting state for long periods (months in 
rodents and years in humans). Examination of the phenotype of 
dividing versus nondividing cells suggests that typical naive T cells 
are long-lived resting cells whereas the majority of effector and 
memory T cells have a much more rapid turnover. However, some 
memory T cells appear to divide very infrequently and eventually 
return to a resting state. The factors controlling the generation and 
maintenance of memory T cells are discussed. [References: 57]

http://www.ncbi.nl
m.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids
=7613491&dopt=Abstract