Cleaved L-selectin concentrations in meningeal leukaemia

Involvement of the central nervous system has important therapeutic implications in acute leukaemia. Because the identification of blast cells in cerebrospinal fluid (CSF) is often difficult, there is a need for sensitive markers of leukaemic infiltration. Since the shed form of L-selectin (sL-selectin) is frequently increased in acute leukaemia (sL-selectin* leukaemia), we examined whether assay of sL-selectin in CSF could improve our ability to detect such meningeal involvement. CSF sL-selectin was significantly (p<0·001) higher in 15 patients with sL-selectin+ meningeal leukaemia (median 60 ng/mL, range 34-150) than in 20 patients with acute leukaemia without meningeal involvement (12 ng/mL, 1-39) or 88 control patients (14 ng/mL, 0-37). Serial measurements of sL-selectin in patients with sL-selectin+ leukaemic meningitis showed increased CSF concentrations of the cleaved receptor in 4 patients with therapy-resistant meningeal leukaemia and sustained normal concentrations in 9 patients in remission. Our results suggest that CSF sL-selectin may be a useful marker in the detection of meningeal involvement by blast cells in patients with sL-selectin+ leukaemia.