Hemolytic anemia due to a mixture of low-titer IgG lambda and IgM lambda agglutinins reacting optimally at 22 degrees C.

A 65-year-old white man had severe hemolytic anemia due to a mixture of low-titer IgG lambda and IgM lambda agglutinins showing optimum reactivity at 22 degrees C. The IgG agglutinins were detected by manual indirect antiglobulin test (IAT) using anti-IgG, and had a titer of 1 at 37 degrees C, 128 at 22 degrees C and 16 at 4 degrees C against adult type O red blood cells (RBC). The corresponding titers with cord RBC were 1 (37 degrees C), 64 (22 degrees C) and 8 (4 degrees C). Proteolytic enzyme and neuraminidase treatment of RBC did not decrease these titers. No known specificity could be assigned to these agglutinins. The isolated agglutinins (recovered by cold adsorption, warm elution) were shown by immunoelectrophoresis to be IgG lambda antibodies. They did not bind complement in vitro, consistent with the finding that the patient had negative manual direct antiglobulin test (DAT) by anti-C3d. It could be shown only by automated IAT that patient's serum also contained IgM cold agglutinins which also reacted best at 22 degrees C and appeared to be of lambda light-chain type. The patient responded to corticosteroid therapy and remains well without treatment 14 months after the hemolytic episode. The presence of IgG cold agglutinins may be predictive of a favorable response to corticosteroid therapy.