Differences in cerebral extracellular response of interleukin-1β, interleukin-6, and interleukin-10 after subarachnoid hemorrhage or severe head trauma in humans.

BACKGROUND

Microdialysis has become a routine method for biochemical surveillance of patients in neurosurgical intensive care units.

OBJECTIVE

To analyze the intracerebral extracellular levels of 3 interleukins (ILs) during the 7 days after major subarachnoid hemorrhage or traumatic brain injury).

METHODS

Microdialysate from 145 severely injured neurosurgical intensive care unit patients (88 with subarachnoid hemorrhage, 57 with traumatic brain injury) was collected every 6 hours for 7 days. The concentrations of IL-1β and IL-6 were determined by fluorescence multiplex bead technology, and IL-10 was determined by enzyme-linked immunosorbent assay.

RESULTS

Presented are the response patterns of 3 ILs during the first week after 2 different types of major brain injury. These patterns are different for each IL and also differ with respect to the kind of pathological impact. For both IL-1β and IL-6, the initial peaks (mean values for all patients at day 2 being 26.9 ± 4.5 and 4399 ± 848 pg/mL, respectively) were followed by a gradual decline, with IL-6 values remaining 100-fold higher compared with IL-1β. Female patients showed a stronger and more sustained response. The response of IL-10 was different, with mean values less than 23 pg/mL and with no significant variation between any of the postimpact days. For all 3 ILs, the responses were stronger in subarachnoid hemorrhage patients. The study also indicates that under normal conditions, IL-1β, IL-6, and IL-10 are present only at very low concentrations or not at all in the extracellular space of the human brain.

CONCLUSION

This is the first report presenting in some detail the human cerebral response of IL-1β, IL-6, and IL-10 after subarachnoid hemorrhage and traumatic brain injury. The 3 ILs have different reaction patterns, with the response of IL-1β and IL-6 being related to the type of cerebral damage sustained, whereas the IL-10 response was less varied.