IL-15 is a growth factor and an activator of CD8 memory T cells.
Memory lymphocytes, arising from naïve lymphocytes after antigenic stimulation and being long-lived, are the cellular basis for immunological memory. Recent studies of CD8 T cells suggest that generation of CD8 memory T cells requires the engagement of T cell antigen receptors (TCR) with antigen, yet the maintenance of CD8 memory T cells appears to be dependent on cytokines, such as IL-15, independent of TCR. Although considerable progress has been made in understanding the molecular and cellular events of TCR-induced differentiation and proliferation in the past decade, less is known about the mechanisms of IL-15 action. From a kinetic and comparative analysis of the responses of memory phenotype CD8 T cells to IL-15 and TCR stimulation in vitro, we found that IL-15 and anti-CD3 induce highly similar responses in memory phenotype CD8 T cells as measured by general gene expression profiles, synthesis of effector molecules (IFNgamma, TNFbeta, granzyme B and perforin), induction of cytotoxicity, and cellular proliferation. These findings indicate that IL-15 is not only a growth factor but also an antigen-independent activator for CD8 memory T cells.
Weng
Nan-Ping
NP
Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA. wengn@grc.nia.nih.gov
Liu
Kebin
K
Catalfamo
Marta
M
Li
Yu
Y
Henkart
Pierre A
PA
D000818:Animals; D017252:CD3 Complex / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology*; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D006133:Growth Substances / Q000494:pharmacology / Q000502:physiology; D006801:Humans; D007156:Immunologic Memory / Q000187:drug effects; D066298:In Vitro Techniques; D019409:Interleukin-15 / Q000494:pharmacology* / Q000502:physiology; D008213:Lymphocyte Activation / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism
D017252:CD3 Complex; D016207:Cytokines; D006133:Growth Substances; D019409:Interleukin-15; D011948:Receptors, Antigen, T-Cell