BI-28 * NEW MONOCYTE SUBTYPING DISTINGUISHES GLIOMA PATIENTS FROM HEALTHY CONTROLS

Abstract

BACKGROUND: Monocyte subset distribution in blood, based on expression of CD14 and CD16, has been shown to correlate with cancer, auto-immune and infectious disease. Consequently, analysis of monocyte subsets in glioma patients could lead to new insights in diagnosis and monitoring of disease and therapy. We investigated the expression pattern of 58 monocyte markers resulting in the identification of two novel monocyte subsets. These findings were used to investigate the monocyte subset distribution in glioma. METHODS: The expression pattern of 58 antibodies against different monocyte markers was evaluated on blood of 5 healthy volunteers using 8-color flow cytometry with novel technologies and APS software tools of the EuroFlow program (www.euroflow.org). Subsequently we investigated blood from 18 healthy controls and 164 glioma-suspected patients for the conventional monocyte subset distribution. Fifty-five of these patients were also investigated with our novel 8-color flow cytometric antibody panel for studies of the novel monocyte subsets. RESULTS: Eight of the evaluated 58 monocyte markers allowed the identification of two new monocyte subsets in addition to the three conventional subsets. Absolute numbers of monocytes and one subset were significantly reduced in the grade II and III glioma compared to cerebral metastasis. Furthermore we found that two other subsets were significantly decreased and one increased (relative and absolute) in our patients compared to healthy controls (p < 0.001). Moreover one subset showed a significant negative correlation with glioma diameter (P < 0.001). No correlation between the different subsets and dexamethasone usage was found. CONCLUSIONS: The relative and absolute distribution of monocyte subsets appeared to be significantly different between glioma patients, cerebral metastasis, and healthy controls. One subset significantly correlated with glioma diameter. We are currently investigating whether the differences in subset distribution predict outcome and/or therapy efficacy. Monocyte subset analysis might be applicable as diagnostic and monitoring tool in glioma patients.