Relationship of CSF leukocytosis to compartmentalized changes in MCP-1/CCL2 in the CSF of HIV-infected patients undergoing interruption of antiretroviral therapy

Although monocyte chemoattractant protein (MCP-1)/CCL2 is believed to mediate trafficking of HIV-activated leukocytes into the CNS, its role has not been studied directly in humans. To evaluate MCP-1's effects on CNS leukocyte infiltration, we measured CSF leukocytes and MCP-1 levels in serial plasma and cerebrospinal fluid (CSF) samples from subjects who experienced large increases in viral load after interrupting antiretrovirals. Following large increases in CSF MCP-1, CSF leukocytosis (15–166 cells/μL) developed in 4 of 6 subjects. Both initial MCP-1 levels and subsequent changes were 3-fold larger in CSF than plasma. The magnitude and timing of changes suggested that MCP-1 triggers the development of CSF pleocytosis.