CROSS-REACTIVITY OF ANTIBODIES IMMUNOADSORBED TO LAMININ WITH RECOMBINANT HUMAN LA (SS-B) PROTEIN

Anti-La (SS-B) antibodies cross-reacting with mouse B1 laminin were re ported in sera of patients with systemic lupus erythematosus. However, the common epitope had not been characterized. Immunoblotting conditi ons were established, allowing detection and elution of anti-La (SS-B) /laminin cross-reacting antibodies. Antibodies adsorbed to mouse B1 la minin represented a subclass of anti-La antibodies. They strongly reac ted with human full length recombinant La protein. However, they faile d to react with either an N-terminal La peptide consisting of amino ac ids 1-192 or a C-terminal La peptide starting at methionine 223, while they still reacted with recombinant La peptides consisting of the ami no acids 1-341 or starting at 192. These data indicate that the La (SS -B)/laminin epitope is located between amino acids 192-223 of human La protein, which includes the amino acids EAKLRA, common to the nuclear autoantigen La (SS-B) and the human or mouse B1 laminin. (C) 1998 Aca demic Press Limited.