Measurement of Donath-Landsteiner antibody-producing cells in idiopathic nonsyphilitic paroxysmal cold hemoglobinuria (PCH) in children

2-yr-old girl with a nonsyphilitic type of paroxysmal cold hemoglobinuria (PCH) is reported. We applied the plaque-forming cell (PFC) assay to the measurement of Donath-Landsteiner (DL) antibody- producing cells in the patient. Some of the circulating B lymphocytes formed plaques in our assay system. Initially the number of PFC was 1442 +/- 225/10(6) lymphocytes and DL titer was 1:16. Thereafter the PFC decreased in number as the DL titer decreased. Eight weeks later circulating PFC were not found but the DL titer was still 1:1 positive. The PFC assay appears to be useful as a new method for obtaining rapid imformation as to the disease status of PCH.