CMV-induced anti-Sia-b1 cold agglutinin in an immunocompromised patient

In postinfection cold agglutination, certain cold agglutinin (CA) specificities are associated with distinct infectious agents. The combined occurrence of anti-I and anti-Sia-b1 CAs following Mycoplasma pneumoniae infection has been reported recently. After renal transplantation and hyperacute graft rejection, transiently occurring CAs were observed in an 18-year-old boy. The CAs were characterized by serum cold absorption with sialidase-treated red cells and warm elution from the cells. An anti-Sia-b1 CA could be differentiated from an accompanying low-liter anti-I. Fresh infections with Mycoplasma pneumoniae, Epstein-Barr virus, rubella, and varicella viruses were excluded, but CMV infection was demonstrated. This is the first case of a postinfection anti-Sia-b1 CA associated with CMV infection.