A murine model of human cold agglutinin disease

Progress has been limited in the treatment of cold agglutinin (CA) disease by the absence of an animal model. We have recently studied at the molecular level one CA displaying the rare anti-Sia-1b specificity (CAGAS), CAGAS displays strong CA activity and is able to haemolyse mouse RBC in the presence of complement, thus constituting a suitable Ab for creating a murine model of CA disease. In the present work we introduced CAGAS VH and VL domains into eukaryotic expression vectors and transfected them into the non-secreting mouse myeloma X63 cell line. Clones expressing complete engineered pentameric IgM kappa CAGAS (eCAGAS) recapitulating the characteristics of serum CA (sCAGAS) could be obtained. The i.p. injection of eCAGAS to normal BALB/c mice induced a typical haemolytic anaemia, as demonstrated by the presence of spontaneous cold agglutination of RBC, induction of anaemia and significant reticulocytosis. Of interest, conspicuous bilateral ear loss was observed in one of these animals. In addition, i.p. injection of X63 transfected line into BALB/c nude mice induced ascites, typical haemolytic anaemia, and shortening of the mean RBC survival. These findings validate the practical interest of constructing a transgenic mouse model expressing eCAGAS.