Antibody-mediated suppression of erythropoiesis in dogs with red blood cell aplasia.

Eight dogs with acquired RBC aplasia were studied. Unfractionated sera and serum immunoglobulin G fractions were examined for the presence of erythroid progenitor cell inhibitors. A serum immunoglobulin G inhibitor directed against precursors of erythroid colony-forming units was detected in 3 of 5 dogs that were direct Coombs' test-negative and in 1 of 3 dogs that were direct Coombs' test-positive. Sera from these dogs were treated with binary ethyleneimine to inactivate any viruses present. The inhibitory effects of the treated serum on erythroid colony-forming units was not ameliorated.