Intrathecal production of specific IgA antibodies in CNS infections

Cerebrospinal fluid (CSF) and serum from subjects with herpes simplex encephalitis, herpes zoster, mumps meningitis and neuroborreliosis were analysed for the presence of immunoglobulin A (IgA) and G (IgG) antibodies to the corresponding four antigens. Specific intrathecal IgA antibody synthesis as manifested by an elevated index was a frequent finding. Higher IgA index values than the corresponding IgG was seen in one third of the samples from subjects with herpes simplex encephalitis and herpes zoster. Correlation between specific IgG and IgA index was most pronounced for varicella-zoster virus (r = 0.66, P < 0.001). In subjects with mumps meningitis a strong intrathecal IgA and IgG antibody response to Borrelia burgdorferi was demonstrated. Specific herpes simplex and varicella-zoster virus IgA was not found to contain secretory component, thus contradicting an active secretion into the CNS compartment. In conclusion, our data indicate that specific IgA is intrathecally produced in herpes simplex encephalitis, herpes zoster and mumps meningitis but is a rare finding in neuroborreliosis.