Diagnostic utility of CSF soluble CD27 for primary central nervous system lymphoma in immunocompetent patients

The aim of this study is to determine the diagnostic utility of cerebrospinal fluid (CSF) soluble CD27 (sCD27) as a tumor marker for primary central nervous system lymphoma (PCNSL) in immunocompetent patients. A total of 93 CSF samples were collected from the following four patient groups: the PCNSL group, 13 patients (26 samples) with PCNSL, 12 samples obtained at initial diagnosis, 10 during therapy, four at complete remission; the other brain tumors (OBT) group, 30 patients (30 samples) with other brain tumors; the other neurological diseases (OND) group, 25 (25 samples) with other neurological diseases; the inflammatory neurological diseases (IND) group, 12 patients (12 samples) with inflammatory neurological diseases. sCD27 levels were determined by sandwich enzyme-linked immunosorbent assay. The optimal cut-off value was found to be 15 U ml-1. The CSF sCD27 levels were over 15 U ml-1 in 23 of the 26 PCNSL samples and were significantly higher than those in the OBT and OND groups in which all samples were below 15 U ml-1. Elevated CSF sCD27 levels were also observed in 11 of 12 IND samples. In the two PCNSL patients whose CSF sCD27 levels were studied longitudinally, the sCD27 levels correlated very well with remission and relapse of the disease. CSF sCD27 is useful as a tumor marker for PCNSL in immunocompetent patients, and is also useful to evaluate the effect of various types of treatment. Although there was a large cross-reactivity in the CSF sCD27 levels between PCNSL and IND group, white blood cell count in the CSF is helpful to distinguish these two diseases.