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J. Exp. Med.,
Volume 186, Number 9, November 3, 1997 1407-1418
By
From the Department of Clinical Viro-Immunology, Central Laboratory of the Netherlands Red Cross
Blood Transfusion Service, and Laboratory of Experimental and Clinical Immunology of the University
of Amsterdam, 1066 CX Amsterdam, The Netherlands
Human CD8+ memory- and effector-type T cells are poorly defined. We show here that, next
to a naive compartment, two discrete primed subpopulations can be found within the circulating human CD8+ T cell subset. First, CD45RA
CD45R0+ cells are reminiscent of memory-type T cells in that they express elevated levels of CD95 (Fas) and the integrin family members CD11a, CD18, CD29, CD49d, and CD49e, compared to naive CD8+ T cells, and are able to
secrete not only interleukin (IL) 2 but also interferon
, tumor necrosis factor
, and IL-4. This subset does not exert cytolytic activity without prior in vitro stimulation but does contain virus-specific cytotoxic T lymphocyte (CTL) precursors. A second primed population is characterized by CD45RA expression with concomitant absence of expression of the costimulatory
molecules CD27 and CD28. The CD8+CD45RA+CD27
population contains T cells expressing high levels of CD11a, CD11b, CD18, and CD49d, whereas CD62L (L-selectin) is not
expressed. These T cells do not secrete IL-2 or -4 but can produce IFN-
and TNF-
. In accordance with this finding, cells contained within this subpopulation depend for proliferation
on exogenous growth factors such as IL-2 and -15. Interestingly, CD8+CD45RA+CD27
cells
parallel effector CTLs, as they abundantly express Fas-ligand mRNA, contain perforin and
granzyme B, and have high cytolytic activity without in vitro prestimulation. Based on both
phenotypic and functional properties, we conclude that memory- and effector-type T cells can
be separated as distinct entities within the human CD8+ T cell subset.
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