Chlamydia pneumoniae in multiple sclerosis: humoral immune responses in serum and cerebrospinal fluid and correlation with disease activity marker.

Humoral immune responses to Chlamydia pneumoniae (C. pneumoniae) were studied in paired sera and cerebrospinal fluid (CSF) of patients with definite multiple sclerosis (MS) and other inflammatory and non-inflammatory neurological diseases. Seropositivity was not significantly different between these groups. However, C. pneumoniae-specific IgG titers were significantly higher in CSF of MS than in controls. Sixteen out of 52 seropositive MS patients (30.8%) showed intrathecal synthesis of C. pneumoniae-specific IgG but only one of 43 seropositive controls (2.3%). In MS, this was strongly associated with intrathecal synthesis of polyclonal IgG in 13/16 patients. However, these elevated C. pneumoniae antibody titers in CSF did not significantly correlate with disease duration, disease course, clinical or MRI disease activity, disability or presence of oligoclonal IgG in MS.