[Soluble lymphocyte antigens in hematological diseases]

Plasma levels of soluble CD8 (sCD8) and soluble CD4 (sCD4) in patients with infectious mononucleosis (IM) and hematological disorders were studied. In IM patients, a marked increase in sCD8 (22, 366 +/- 2,702U/ml, control: 219 +/- 10U/ml, p < 0.0001) and significant increase in sCD4 (19.3 +/- 0.9, control: 8.1 +/- 0.2, p < 0.0001) strongly suggest activation of both CD8+ and CD4+ lymphocytes, which is important in restraining Epstein-Barr virus-infected B lymphocytes. We showed that the elevation of plasma sCD8 is due to expansion of CD8+ subset as well as increased sCD8 release from each CD8+ cell. Increased sCD4 release from CD4+ lymphocytes was also seen. During convalescence sCD8 and sCD4 levels showed progressive decrease; however, even at 60-120 days after onset the levels of sCD8 and sCD4 remained higher than normal, suggesting prolonged lymphocyte activation. In hematological malignancies, elevated serum levels of sCD4 and sCD8 were found in non-Hodgkin lymphoma (NHL), acute lymphocytic leukemia, multiple myeloma, acute non-lymphocytic leukemia and chronic myelogenous leukemia. Levels of sCD4 and sCD8 in patients with NHL reflect disease status and are useful in monitoring disease activity.