CEREBROSPINAL FLUID AND SERUM LEVELS OF ANTI-CHLAMYDIA PNEUMONIAE IGA IN PATIENTS WITH MULTIPLE SCLEROSIS

Objectives: Chlamydia pneumoniae (C. pneumoniae) is currently believed to be a potential co-factor in Multiple Sclerosis (MS) pathogenesis. In fact, intrathecally synthesized anti-C. pneumoniae high-affinity IgG and C. pneumoniae-specific CSF-restricted oligoclonal IgG bands were found in patients with MS progressive forms (1). In the setting of C. pneumoniae-specific humoral immune response, anti-C. pneumoniae IgA can be implicated in the reactivation as well as in the protection against C. pneumoniae infection. However, CSF and serum concentrations of anti-C. pneumoniae IgA have not yet been intensively investigated in MS. Materials: We analyzed 59 relapsing-remitting (RR), 9 secondary progressive (SP) and 15 primary progressive (PP) MS patients grouped according to clinical and Magnetic Resonance Imaging (MRI) evidence of disease activity. Seventy-two patients with other inflammatory neurological disorders (OIND) and 59 with non-inflammatory neurological disorders (NIND) were used as appropriate controls. Methods: CSF and serum levels of anti-C. pneumoniae IgA were measured by ELISA technique. Quantitative intrathecal synthesis of anti-C. pneumoniae IgA was determined by Antibody Specific Index (ASI). Results: CSF and serum concentrations of anti-C. pneumoniae IgA were higher in OIND (p < 0.0001, and p < 0.02, respectively) and NIND (p < 0.01 and p < 0.02, respectively) than in MS patients. Abnormal ASI values indicative of a C. pneumoniae-specific intrathecal IgA synthesis were more elevated in OIND (16/72; 22.2%) than in MS (3/83; 3.6%; p < 0.001) and NIND (3/59; 5.1%; p < 0.02). Anti-C. pneumoniae IgA CSF levels were greater in SP and PP than in RR MS (p < 0.02). No significant differences were found for CSF and serum mean concentrations of anti-C. pneumoniae IgA and for abnormal ASI values between MS patients categorized according to clinicalforms and appearance of clinical and MRI activity. Discussion: Our findings suggest that anti-C. pneumoniae IgA may play a dual role in MS. First, lower CSF and serum levels of anti-C. pneumoniae IgA detected in MS compared to controls could reflect an increased susceptibility for C. pneumoniae infection in MS. Second, higher CSF IgA concentrations measured in SP and PP than in RR MS could indicate persistent and repeated C. pneumoniae infection in patients with MS progressive forms. Conclusions: C. pneumoniae IgA antibodies are considered the most relevant and clinically significant marker for ongoing C. pneumoniae infection or reactivation compared to the other Ig classes (2). Their detection in larger extent in SP and PP forms may have clinical significance in MS pathogenesis.