Monoclonal anti-poly(rA) hybridoma antibodies from an autoimmune MRL/MpJ-lpr/lpr mouse

Three B cell hybridomas were produced by the fusion of spleen cells from a 5 month old MRL/Mp-lpr/lpr mouse with the myeloma cell line, NS-1. By competitive inhibition, all three monoclonal antibodies (MoAb) were specific for poly(rA) and were inhibited to a lesser extent by dDNA, nDNA, poly(rI) and poly(rC). Moreover, the three MoAb were not inhibited by mononucleosides and the nucleotide, ATP. Competitive inhibition, using poly(rA) of defined lengths, showed that the recognition site among the MoAb varied, one demonstrating binding of poly(rA) as small as two bases in length. This study suggests that the spontaneous autoimmune repertoire to poly(rA) is restricted as compared to other monoclonal autoantibodies to nucleic acids, but contains within itself microheterogeneity.