Antibodies against GM1-ganglioside not detectable by standard methods in neurological patients.

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

Villa Carlos Paz, Córdoba, Argentina

Congreso; XXXVII Reunión Nacional de Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 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 GM1 produce anti-GA1 IgG-antibodies that do not react with GM1 in standard immunoassays (ELISA and HPTLC-immunostaining). The antibody binding to GA1 was inhibited by soluble GA1 but also by GM1. These results indicate the existence in rabbits of antibodies reacting with epitopes present on both molecules that are not exposed by GM1 in standard immunoassays. After that, we investigated the presence of these unusual anti-GA1/GM1 antibodies in normal human sera (NHS) and neurological patient sera (PS). High titers of anti-GA1 antibodies not cross-reacting with GM1 were detected in 17 PS out of 292 analyzed. Of these, 8 sera showed binding that was inhibited by soluble GM1 (10-5 M). However only 6 sera presented changes in affinity when comparing to NHS. In addition some antibodies were able to recognize GM1 in affinity columns. This new type of anti-GM1 antibodies able to recognize its target antigen under conditions not present in standard immunoassays could be important in the etiology and diagnosis of neurological diseases.