Purpose Applying current diagnostic methods, overt CNS involvement is a rare event in childhood acute lymphoblastic leukemia (ALL). In contrast, CNS-directed therapy is essential for all patients with ALL because without it, the majority of patients eventually will experience relapse. To approach this discrepancy and to explore potential distinct biologic properties of leukemic cells that migrate into the CNS, we compared gene expression profiles of childhood ALL patients with initial CNS involvement with the profiles of CNS-negative patients. Patients and Methods We evaluated leukemic gene expression profiles from the bone marrow of 17 CNS-positive patients and 26 CNS-negative patients who were frequency matched for risk factors associated with CNS involvement. Results were confirmed by real-time quantitative polymerase chain reaction analysis and validated using independent patient samples. Results Interleukin-15 (IL-15) expression was consistently upregulated in leukemic cells of CNS-positive patients compared with CNS-negative patients. In multivariate analysis, IL-15 expression levels greater than the median were associated with CNS involvement compared with expression equal to or less than the median (odds ratio [OR] = 10.70; 95% CI, 2.95 to 38.81). Diagnostic likelihood ratios for CNS positivity were 0.09 (95% CI, 0.01 to 0.65) for the first and 6.93 (95% CI, 2.55 to 18.83) for the fourth IL-15 expression quartiles. In patients who were CNS negative at diagnosis, IL-15 levels greater than the median were associated with subsequent CNS relapse compared with expression equal to or less than the median (OR = 13.80; 95% CI, 3.38 to 56.31). Conclusion Quantification of leukemic IL-15 expression at diagnosis predicts CNS status and could be a new tool to further tailor CNS-directed therapy in childhood ALL.
P67 Aims: Ischemia and reperfusion (I/R) during heart transplantation results in inflammation and cell death. Lipocalin-2 (24p3), a member of the lipocalin protein superfamily, is a marker for acute inflammatory response and induction of apoptosis. The aim of this study was to investigate 24p3 expression in association with the presence of apoptosis in a murine cardiac transplant model. Methods: C57BL/6 hearts were heterotopically transplanted to syngeneic recipients. Grafts were transplanted immediately or underwent 10h of cold ischemia prior to transplantation. At 2min., 2h, 12h, 24h, 2 and 10 days after transplantation (n=5 per group and timepoint) graft function was assessed before organ retrieval. RT-PCR and cDNA microarrays were performed for gene expression analysis. Morphology was determined by HE histology, protein production was investigated by immunohistochemistry using a polyclonal antibody. Apoptosis was analysed using TUNEL assay. Results: 10h of cold ischemia resulted in impaired graft function immediately after reperfusion. At later timepoints, however, there was no difference anymore. HE staining demonstrated dense mononuclear infiltrates, cellular edema and small focal necrosis in groups with and without 10 hours of cold ischemia. 24p3 gene expression was first upregulated at 12h, transcription was higher in groups without cold ischemia (22/8,8-fold). At later timepoints, 24p3 was found at lower levels in both groups. Upregulation of gene transcription was reproducible by PCR. 24p3 positive cells were identified as granuolcytes and macrophages. Apoptotic cells were first detectable at 2 days, the number peaked 10 days after transplantation. Conclusions: This study demonstrates expression of 24p3 following I/R in cardiac transplantation by infiltrating leukocytes. 24p3 production is associated with apoptosis in transplanted hearts. Prolonged cold ischemia does not enhance 24p3 expression. Lipocalin-2 is potentially a novel mechanism to induce apoptosis in the chosen setting and antagonization may provide a strategy to prevent organ damage in response to ischemia and reperfusion.
