Antibodies against GD1a ganglioside not detectable by standars methods in neurological patients.

LOPEZ PHH,; COMIN R,; VILLA A,; DI EGIDIO M,; SAIZAR R,; SICA REP,; NORES GA.

Puerto Iguazú, Argentina

Congreso; ISN-ASN Sphingolipid Satellite Meeting; 2001

High titers of anti-GA1 antibodies have been associated with motor syndromes. In most cases, these antibodies cross-react with GM1. We found that rabbits immunized with GD1a produce anti-GA1 IgG-antibodies that do not react with GD1a in standard immunoassays (ELISA and HPTLC-immunostaining). The binding to GA1 was inhibited by soluble GA1 but also by GD1a. These results indicate the existence in rabbits of antibodies reacting with epitopes present on both molecules that are not exposed by GD1a in standard immunoassays. After that, we investigated the presence of these unusual anti-GA1/GD1a antibodies in neurological patient sera. High titers of anti-GA1 IgG-antibodies not cross-reacting with GM1 were detected in 18 patient sera out of 292 analyzed. Of these, 9 sera showed binding that was inhibited by soluble GD1a (10-5 M). However only 7 sera present changes in affinity when comparing to NHS. In addition the antibodies with high affinity to soluble GD1a were able to recognize GD1a in affinity columns. This new type of anti-ganglioside antibodies able to recognize its target antigen under conditions not present in standard assay methods could be important in the etiology  and diagnosis of neurological diseases.