Regarding laboratory examinations, all patients had abnormalities in liver function, hemogram findings such as moderate and severe anemia, and a reduced number of blood platelets. Other findings associated with blood coagulation included significantly reduced fibrinogen levels, significantly elevated serum ferritin levels, hyperplasia, and histiocytic hemophagocytosis in the bone marrow. Apart from this, the patients showed increased levels of inflammatory markers such as erythrocyte sedimentation rate and C-reactive protein/high-sensitivity C-reactive protein. In addition, 7 patients had a reduced leukocyte or neutrophil counts, 3 of whom exhibited granulocytosis. Six patients showed diminished natural killer (NK) cell activity and reduced numbers of NK cells. Three patients underwent a serum CD25 level examination, and CD25 was elevated in all patients. Four patients underwent serum β2-microglobulin examination, and the level was elevated in 3 patients, whereas it was normal in 1 patient.