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Anti-GM1 ganglioside IgM-antibodies present in human plasma: affinity and biological activity changes in a patient
R K Mitzutamari1, L J Kremer, E A Basile
1Departamento de Química Biológia, Dr. Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba and CIQUIBIC, CONICET, Argentina.
Abstract:
Low affinity anti-GM1 IgM-antibodies are part of the normal repertoire of human plasma antibodies (Mizutamari et al.: J Neuroimmunol 50:215-220, 1994), a fact that is against the pathological role proposed for them in autoimmune diseases. Here we present evidence that these low affinity IgM-antibodies are devoid of complement-mediated lytic activity to GM1-liposomes, suggesting that they should not be considered harmful. In contrast to the absence in normal individuals, in the plasma of a patient with sensory polyneuropathy we detected high affinity anti-GM1 IgM-antibodies. Concomitant with the presence of these high affinity anti-GM1 IgM-antibodies, the patient plasma is capable of producing complement-mediated lysis of GM1-liposomes. These results suggest that an increase in the affinity of the naturally existing anti-GM1 antibodies could be the trigger that switches them from non-harmful to pathological.