We hitherto reported that the activation of the complement system was closely related to the genesis of late cerebral vasospasm after subarachnoid hemorrhage. At present one of the useful indices for the activation of the complement system is measurement of C1q binding IgG by C1q solid phase enzyme immunoassay. Therefore we measured C1q binding IgG in CSF and in serum from patients with SAH by C1q solid phase enzyme immunoassay and examined the relationship between the activation of the complement system and late cerebral vasospasm. Thirty six CSF samples and 13 serum samples were collected from 19 patients with SAH. C1q binding IgG was detected in 19 out of 25 CSF samples (76%) collected at the time when cerebral vasospasm was recognized.
On the other hand, only 2 CSF samples (18%) contained C1q binding IgG in 11 CSF samples which were collected from patients without cerebral vasospasm. The difference was significant. In 13 cases C1q binding IgG both in CSF and in serum was measured at the same time. In 5 out of 13 cases the level of C1q binding IgG in CSF was greater than that in serum. C1q binding IgG was not detected either in CSF or in serum in 5 of these 13 cases. This result suggested that C1q binding IgG in CSF was not transferred from blood but was formed in the subarachnoid space. Moreover, C1q binding IgG was detected in 17 of 23 CSF samples collected on 4-14 th day after SAH. From these data, there was close relationship between C1q binding IgG in CSF and late cerebral vasospasm.
