Anti-"i" antibody and hemolytic anemia associated with spontaneous cytomegalovirus mononucleosis.

Hemolytic anemia occurred in a 23-year-old woman with spontaneous cytomegalovirus mononucleosis who had not received a blood transfusion. The patient's serum gave positive reactions in Coombs' antiglobulin test with human cord erythrocytes but did not react with adult "O" cells. Complement-fixation antibody titers against cytomegalovirus and levels of activity against cord erythrocytes increased as the anemia worsened and remained at high levels when recovery from the anemia occurred.