Elevated soluble CD4 levels in the cerebrospinal fluid in patients with adult T-cell leukemia

Levels of the soluble form of the leukocyte surface antigen CD4 (sCD4) were measured by enzyme linked immunosorbent assay (ELISA) in the cerebrospinal fluid (CSF) of patients with adult T-cell leukemia (ATL) and other malignant and non-malignant diseases. All patients with ATL and meningeal infiltration had markedly elevated levels of sCD4 in the CSF (53.7 ± 34.9 U/ml). ATL patients without CSF pleocytosis often had elevated levels of sCD4 (15.1 ± 9.2 U/ml). Non-ATL patients with CSF pleocytosis had elevated levels of sCD4 (23.3 ± 12.2 U/ml) and those without CSF pleocytosis also showed elevation of sCD4 levels (16.8 ± 9.3 U/ml). However, the mean levels of sCD4 in CSF from these patients were significantly lower than ATL patients with meningeal infiltration. Soluble CD4 in the CSF from healthy volunteers were below the detectable limit. We conclude that meningeal infiltration of CD4(+) ATL cells is strongly associated with elevated sCD4 levels in CSF, and some part of sCD4 in CSF may be originated from the native cells in the CNS as a response of inflammatory stimulations. Therefore, measurement of sCD4 may be useful in the diagnosis of meningeal infiltration and/or meningeal irritation in patients with ATL. © 1994 Wiley-Liss, Inc.