Similar humoral and cellular immunological reactivities to human herpesvirus 6 in patients with multiple sclerosis and controls

Several studies have suggested an association between human herpesvirus 6 ( HHV-6) and multiple sclerosis (MS). We have previously studied intrathecal production of antibody to lymphotropic herpesviruses in MS patients and the presence of human herpesvirus 1 to 7 DNAs in cerebrospinal fluid (CSF). In the present study anti-HHV-6 immunoglobulin M (IgM) in serum and anti-HHV- 6 IgG subclasses in serum and CSF were examined and the lymphoproliferative response to HHV-6 was analyzed. The PCR examination was refined by purifyi ng DNA from CSF and retesting the samples for HHV-6 DNA. There were no stat istically significant differences between the groups concerning IgM positiv ity, distribution of IgG subclasses, or lymphoproliferative response to HHV -6, The purification of DNA increased the number of PCR-positive samples fr om 0 of 71 to 4 of 68. The study does not give additional support to the po ssibility that HHV-6 is a common cause of MS, but a role for the virus in a subset of patients cannot be excluded.