Abstracts (complete list) - Wissenschaft Online

Stefan Maßen, Dirk Jäger, Inka Seil, Barbara Mosetter, Christine Falk
Phenotypic and functional characterization of KIR-expressing
cytotoxic T cells
Introduction: Expression of NK receptors of the KIR (Killer-Ig-like-receptor) family is
mainly observed on NK cells. However, some cytotoxic T cells (CTL) have been shown to
express KIR following allogeneic or tumorspecific stimulation, they have also been
detected in peripheral blood of patients with autoimmune diseases like rheumathoid
arthritis.
Materials and Methods: We generated cytotoxic T cell lines by stimulating isolated
CD8 positive T cells with peptides derived from the tumor associated antigens Rab38
and NY-BR-1 that are mainly expressed by melanoma and breast cancer cells,
respectively. The phenotypic characterization with respect to KIR and NK receptor
expression was determined by multicolour flow cytometry. The specificities of the CTL
lines were examined in chromium-release assays and CD107a-degranulation assays
targeting Rab38- or NY-BR-1-loaded T2-cells. Cytokine secretion patterns were
quantified by multiplex-analyses (Luminex).
Results: Through an extensive phenotypic analysis, the CTL showed a broad expression
of KIR receptors in addition to the activating receptors NKG2D and 2B4. The
functionality of these receptors and their activating and inhibitory potential, tested in
redirected-degranulation experiments, demonstrated that the cytotoxicity of the CTL
lines was clearly dependent on the TCR complex. Activating as well as inhibitory KIR
receptors have only a minor regulatory potential, even though the activating NK
receptor, NKG2D, displayed some co-stimulatory effect. All CTL lines showed de novo
secretion of GM-CSF, IFN-γ and TNF-α as a result of the TCR-complex-stimulation. In
addition, the constitutive secretion of MIP-1β was significantly increased upon TCR
triggering.
Taken together, these data indicate that even in an autologous peptide-specific
stimulation, some CTL maintain their KIR expression, although these KIR may be
functionally dissociated from the TCR signaling cascade. In addition, these KIR-positive
CTL displayed mixed cytokine/chemokine patterns distinct from classical TH1/TH2
patterns.