Novel monoclonal antibodies against proteolipid protein peptide 139-151 demonstrate demyelination and myelin uptake by macrophages in MS and marmosetEAE lesions

Experimental autoimmune encephalomyelitis (EAE) induced by immunization of mice with epitopes of the proteolipid protein (PLP), a major myelin constit uent, forms a useful model for the study of multiple sclerosis (MS). In add ition. MS patients display PLP-specific T- and B-cell responses. suggesting that PLP reactivity is relevant to pathogenesis. Here. the generation and characterization of a panel of mouse monoclonal antibodies (Mab) against PL P139-151. the prominent encephalitogenic sequence in SJL/J mice is describe d. Five Mab were generated by conventional immunization of an SJL/J mouse a nd hybridoma generation. These Mab reacted well with the PLP139-151 peptide in ELISA and belonged to the IgG2a and IgG2b subclasses, consistent with C D4 + T helper 1-cell-supported antibody formation. The Mab also efficiently detected PLP peptide-BSA conjugates in Western blot. confirming their mult i-assay applicability. The Mab were subsequently used to determine the occu rrence of demyelination in brains of MS patients and marmoset monkeys with EAE. Immunohistochemistry on both paraffin and frozen sections demonstrated a homogeneous expression of PLP139-151 in normal myelin, and a complete ab sence in lesions containing demyelinated areas, confirming that the Mab can be used as a general myelin marker. In active demyelinating MS lesions. th e Mab visualized the peptide in the cytoplasm of macrophages containing pha gocytosed myelin. In conclusion. this panel of Mab against the encephalitog enic PLP139-151 epitope forms a useful tool for further study of autoantige n expression, demyelination/remyelination and the staging of lesional activ ity in MS patients, as well as in EAE models in distinct animal species. (C ) 2001 Elsevier Science B.V. All rights reserved.