Oligoclonal and polyclonal synthesis of IgG in the central nervous system: an isoelectric focusing study

The IgG pattern in isoelectric focusing (IEF) has been studied in 90 paired samples of cerebrospinal fluid (CSF) and sera obtained from patients in which intrathecal synthesis of IgG without barrier damage was detectable by Reiber's graph and formula (1980, J. Neurol. 224, 89). Thirty patients were affected by multiple sclerosis (MS), 30 by other inflammatory nervous diseases (OID), and 30 by noninflammatory nervous diseases (NID). At IEF two distinct pathological patterns of CSF IgG were detected: oligoclonal bands (OB), prevailing in the MS group (83% of cases), and a "polyclonal"--i.e., diffuse, uniform--increase of CSF IgG, prevailing in the NID (90%). The OID group was intermediate, 57% of cases with OB and 43% with polyclonal CSF IgG patterns. Overall, only 45 of 90 patients synthesizing IgG in the CNS had CSF OB. This suggests that the CNS immune response can imply either the synthesis of IgG of restricted heterogeneity (i.e., OB) or a polyclonal IgG synthesis, giving in IEF a serum-like pattern to the CSF.