[Clinical significance of cytokines-interleukin 6 in disease]

Clinical significance of interleukin 6 (IL-6), a cytokine, is discussed. IL-6 known as an immunoregulatory molecule is produced by various tissues and shows a variety of functions; eg, IL-6 induces B-cell maturation and acute phase protein synthesis in hepatocytes. 1. Pathogenic significance of IL-6 in Castleman's disease. Castleman's disease is a syndrome consisting of lymph node hyperplasia with plasma cell infiltration, hyper-gamma-globulinemia, and an increase of serum level of acute phase proteins. The germinal center of hyperplastic lymph nodes produced large quantities of IL-6. In a patient with a solitary hyperplastic lymph node, clinical improvement and decrease in serum IL-6 were observed following surgical removal of the lymph node. The serum IL-6 level was correlated with clinical data and clinical abnormalities. This indicates that the generation of IL-6 by B cells in germinal centers of hyperplastic lymph nodes of Castleman's disease may be the pathogenesis in this disease. 2. Serum levels of IL-6 in acute inflammatory disease. We analyzed serum levels of IL-6 and acute phase proteins following surgical operations and determined the onset time and degree of inflammatory status. IL-6 levels were reached maximum at 24 hr, and level off within 48 hr. CRP was increased gradually for 48 hr. Maximum levels of IL-6 in the serum of 50 patients were well correlated with those of CRP levels. Serum level of IL-6 correlated with the operation time, but that of CRP did not. Our findings indicate that the elevation of acute phase proteins following surgical trauma may be mediated through IL-6.(ABSTRACT TRUNCATED AT 250 WORDS)