Measurement of Donath - Landsteiner Antibody - producing Cells in Idiopathic

A 2-yr-old girl with a nonsyphilitic type of and DL titer was 1 : 1 6. Thereafter the PFC paroxysmal cold hemoglobinuria (PCH) decreased in number as the DL titer deis reported. We applied the plaque-formcreased. Eight weeks later circulating PFC ing cell (PFC) assay to the measurement of were not found but the DL titer was still Donath-Landsteiner (DL) antibody-produc1 : 1 positive. The PFC assay appears to be ing cells in the patient. Some of the ciruseful as a new method for obtaining culating B lymphocytes formed plaques in rapid information as to the disease status our assay system. Initially the number of of PCH. PFC was 1442 ± 225/106 lymphocytes P AROXYSMAL COLD HEMOGLOBINURIA (PCH) is relatively uncommon. In the earlier period of its history, PCH usually occurred as a chronic complication ofsyphilis, but in recent years it has occurred more often as a transient sequel to certain virus infections, including chickenpox,’ measles,2’3 and mumps.4 In PCH a complement-dependent cold-acting autoantibody, DonathLandsteiner (DL) antibody,5 produces intravascular hemolysis and hemoglobinuria after exposure to the cold. The DL antibody belongs to IgG, and its presence is essential for the diagnosis of the illness. Recent advances in immunology have made it possible to measure antibodyproducing human lymphocytes, although under limited conditions, by plaqueforming cell (PFC) assay. ’#{176} We applied the PFC assay to the measurement of DL antibody-producing cells in PCH. We report the result of PFC assay compared with DL titer in a child with nonsyphilitic PCH.