Cerebrospinal fluid C3 and C4 indexes in immunological disorders of the central nervous system.

Validation of cerebrospinal fluid (CSF) indexes as a measure for intrathecal C3 and C4 production. Examination of their role in differential diagnosis of immunological disorders of the central nervous system (CNS). Correlative study in controls (low back pain without disk herniation) between the CSF/serum ratio (Q) for albumin, and Q C3 and Q C4. Comparative study of C3 and C4 indexes in patients with CNS dysfunction due to relapsing-remitting (RR) multiple sclerosis (MS), secondary progressive (SP) MS, systemic lupus erythematosus (SLE), and human immunodeficiency virus (HIV) infection. Strong and statistically highly significant correlations between Q albumin and Q C3 (r=0.89, P=0.0001), and Q C4 (r=0.68, P= 0.0001). In MS patients decreased mean values for serum (RR, SP) and CSF (RR) C3, and increased C3 index mean value (RR, SP). In CNS SLE increase of mean C3 and C4 index values. In CNS HIV increase of mean C3 and C4 index values, and CSF C3 and C4 concentrations. Most individual index values were within the reference range. CSF index is a valid tool to detect intrathecal C3 or C4 production. C3 or C4 index contributes little to the differential diagnosis of immunological CNS disorders. C3 might play a pathogenic role in various immunological CNS disorders.