multiple sclerosis (ms) is a chronic inflammatory demyelinating disease of the human central nervous system (cns) mediated by autoimmune th1 lymphocytes. we determined the serum levels of autoantibodies for myelin basic protein (mbp), proteolipid (plp) and myelin oligodendrocyte glycoprotein sequence mog 92-106 in a group of 54 healthy individuals and 26 ms patients expressing or not hla dqb1*0602. regardless expression of the susceptibility alelle dqb1*0602, ms patients presented marked (p<0.0001) igg antibody production for mbp and mog92-106. yet, significant (p<0.0001) iga antibody levels were mainly observed for plp and mog antigens. our results suggest that other hla class ii alleles may be conferring susceptibility to ms in this population and influencing the pattern of immune recognition of encephalitogen antigens. furthermore, distinct igg and/or iga autoantibody production may be contributing to the control or maintenance of the cns inflammatory reaction.