title: Augmentation of natural antiganglioside IgM antibodies in lower motor neuron disease (LMND) and role of CD5+ B cells.
abstract: IgM antibodies directed against neuronal gangliosides GM1, GM2, GD1a, GD1b and GT1b occur in normal individuals and their level significantly decreases with age. Patients with lower motor neuron disease (LMND) produce high levels of these autoantibodies. AntiGM1 IgM is selectively augmented. In these patients, the CD5+ (B1) and CD5- (B2) subsets of B cells are not distinct entities but range from those without detectable CD5 marker to those with high CD5+ expression. B1 B cells were sorted to homogeneity, but B2 B cell cannot be isolated to homogeneity because of the presence of B1 cells with low CD5 expression. In short term cultures both the subsets produced IgM antibodies, but the antibodies reacted better with desialylated GM1 than with GM1. Cycloheximide (Cx) (0.35 mM) largely blocked IgM synthesis of the B1 B cells but inhibition of the B2 B cells was incomplete, possibly due to shedding of cytophilic antibodies as well as to the presence of B1 phenotype with loss of CD5 expression. CD5+ B cells may be involved in the production of antiglycolipid IgM.
authors.affiliation: Department of Neurology, Reed Neurological Research Laboratory, University of California, Los Angeles 90024, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Ravindranath
authors.forename: M H
authors.initials: MH
authors.lastname: Ravindranath
authors.forename: M C
authors.initials: MC
authors.lastname: Graves
mesh_terms: D000328:Adult; D000368:Aged; D018941:Antigens, CD19 / Q000032:analysis; D001323:Autoantibodies / Q000276:immunology*; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D018956:CD5 Antigens / Q000032:analysis; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry; D005732:Gangliosides / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000276:immunology*; D009474:Neurons / Q000276:immunology
chemical_list: D018941:Antigens, CD19; D001323:Autoantibodies; D018956:CD5 Antigens; D005732:Gangliosides; D007075:Immunoglobulin M