Cold hemagglutinin disease associated with IgG cold-reactive antibody.

Six patients with chronic idiopathic cold hemagglutinin disease were studied whose serum cold agglutinin was not inactivated or was incompletely inactivated with the IgM-reducing agent dithiothreitol. In five of these patients, isolation of the antibodies revealed that two patients had predominantly IgG cold-reactive antibody, which was associated with smaller amounts of IgM in one patient and with IgA in the other; two patients had predominantly IgM cold agglutinin with lesser amounts of cold-reactive IgG; and one patient had an IgG cold agglutinin only. Both patients with predominantly IgG cold-reactive antibodies were treated with splenectomy and subsequently had a rise in more than hemoglobin levels that has been maintained for over 36 months without additional therapy. Two of the other three patients were treated with glucocorticoids only and responded similarly. These data indicate that a subset of patients with cold hemagglutinin disease have IgG cold-reactive antibodies. In contrast to patients with typical cold agglutinin disease, this subset appears responsive to glucocorticoids and splenectomy.