BCR and myasthenia gravis: We selected two anti-MIR antibody clones to engineer anti-AChR BCR-expressing Nalm-6 target cells, namely clone 637 (derived from a patient with AChR-MG) and clone 192 (derived from a rat) (19, 20), each binding slightly different epitopes in the MIR [dissociation constant (KD) of 637: 0.0050 ± 0.0012 nM; KD of 192: 0.0071 ± 0.0007 nM] (17).