INTRATHECAL IGM, IGA AND IGG ANTIBODY-RESPONSE IN TICK-BORNE ENCEPHALITIS - LONG-TERM FOLLOW-UP RELATED TO CLINICAL COURSE AND OUTCOME

Background: Tick-borne encephalitis (TBE) of western subtype causes lo ng-term morbidity and is considered a health problem in Scandinavia, e astern and central parts of Europe and Russia. The pathophysiology is not fully elucidated. As TBE RNA is rarely demonstrable in cerebrospin al fluid (CSF) the kinetics of the CSF antibody response to the diseas e has attracted attention. Objectives: To investigate the intrathecal TBE-specific antibody response and to correlate its intensity and pers istence to the clinical course. To compare indirect, commercially-base d ELISA methods indexed against albumin ratio ol IgG ratio with the ca pture ELISA method for the establishment of CSF response. Study design : The specific IgM, IgG and IgA antibody responses in serum and CSF we re analysed in 69 Swedish patients included in a prospective study of TEE from the acute phase up to 11-13 months after onset. Results: Anti body response by all three classes was demonstrable in serum and CSF. All methods were useful, but capture technique was the most sensitive and results were easiest to interpret. Peak IgM activity was seen earl y during the disease and persisted after 6 weeks. Maximum IgG levels w ere encountered in late convalescent samples (median 6 weeks). Intrath ecal antibody production was demonstrable in nearly all patients: in 4 1% days 0-6, in 97% days 7-19, in 98% days 21-61 and-at lower levels-i n 84% of the patients after 1 year (50/52 of CSF-serum sampled in the interval 11-61 days). Day 9 after onset, patients with dominating ence phalitic symptoms showed significantly lower intrathecal IgM activity. The persistence of serum and CSF antibodies did not correlate to seve rity of disease. Conclusions: Capture IgM and IgG assays were superior to indirect ELISA. Low early CSF Igm response correlated to encephali tic symptoms, otherwise the intensity and duration of intrathecal anti body response were of limited value for the prediction of clinical cou rse and long-term outcome. (C) 1997 Elsevier Science B.V.